83_FR_29995
Page Range | 29872-30029 | |
FR Document | 2018-13115 |
[Federal Register Volume 83, Number 123 (Tuesday, June 26, 2018)] [Proposed Rules] [Pages 29872-30029] From the Federal Register Online [www.thefederalregister.org] [FR Doc No: 2018-13115] [[Page 29871]] Vol. 83 Tuesday, No. 123 June 26, 2018 Part II Department of Commerce ----------------------------------------------------------------------- National Oceanic and Atmospheric Administration ----------------------------------------------------------------------- 50 CFR Part 218 Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Hawaii-Southern California Training and Testing Study Area; Proposed Rule Federal Register / Vol. 83 , No. 123 / Tuesday, June 26, 2018 / Proposed Rules [[Page 29872]] ----------------------------------------------------------------------- DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 218 [Docket No. 170918908-8501-01] RIN 0648-BH29 Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Hawaii-Southern California Training and Testing Study Area AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Proposed rule; request for comments and information. ----------------------------------------------------------------------- SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for authorization to take marine mammals incidental to the training and testing activities conducted in the Hawaii-Southern California Training and Testing (HSTT) Study Area. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue regulations and subsequent Letters of Authorization (LOA) to the Navy to incidentally take marine mammals during the specified activities. NMFS will consider public comments prior to issuing any final rule and making final decisions on the issuance of the requested MMPA authorizations. Agency responses to public comments will be summarized in the final rule. The Navy's activities qualify as military readiness activities pursuant to the MMPA, as amended by the National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA). DATES: Comments and information must be received no later than August 9, 2018. ADDRESSES: You may submit comments, identified by NOAA-NMFS-2018-0071, by any of the following methods:Electronic submissions: Submit all electronic public comments via the Federal eRulemaking Portal, Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2018-0071, click the ``Comment Now!'' icon, complete the required fields, and enter or attach your comments. Mail: Submit comments to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-3225. Fax: (301) 713-0376; Attn: Jolie Harrison. Instructions: Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on www.regulations.gov without change. All personal identifying information (e.g., name, address, etc.), confidential business information, or otherwise sensitive information submitted voluntarily by the sender may be publicly accessible. Do not submit Confidential Business Information or otherwise sensitive or protected information. NMFS will accept anonymous comments (enter ``N/A'' in the required fields if you wish to remain anonymous). Attachments to electronic comments will be accepted in Microsoft Word, Excel, or Adobe PDF file formats only. FOR FURTHER INFORMATION CONTACT: Stephanie Egger, Office of Protected Resources, NMFS; phone: (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems accessing these documents, please call the contact listed above. SUPPLEMENTARY INFORMATION: Background Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed authorization is provided to the public for review and the opportunity to submit comments. An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such takings are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103 as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival. NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103 as an impact resulting from the specified activity: (1) That is likely to reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by: (i) Causing the marine mammals to abandon or avoid hunting areas; (ii) directly displacing subsistence users; or (iii) placing physical barriers between the marine mammals and the subsistence hunters; and (2) That cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met. The MMPA states that the term ``take'' means to harass, hunt, capture, kill or attempt to harass, hunt, capture, or kill any marine mammal. The 2004 NDAA (Pub. L. 108-136) removed the ``small numbers'' and ``specified geographical region'' limitations indicated above and amended the definition of ``harassment'' as it applies to a ``military readiness activity'' to read as follows (Section 3(18)(B) of the MMPA): (i) Any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild (Level A Harassment); or (ii) Any act that disturbs or is likely to disturb a marine mammal or marine mammal stock in the wild by causing disruption of natural behavioral patterns, including, but not limited to, migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such behavioral patterns are abandoned or significantly altered (Level B Harassment). Summary of Request On September 13, 2017, NMFS received an application from the Navy requesting incidental take regulations and two LOAs to take individuals of 39 marine mammal species by Level A and B harassment incidental to training and testing activities (categorized as military readiness activities) from the use of sonar and other transducers, in-water detonations, air guns, and impact pile driving/vibratory extraction in the HSTT Study Area over five years. In addition, the Navy is requesting incidental take authorization by serious injury or mortality of ten takes of two species due to explosives and for up to three takes of large whales from vessel [[Page 29873]] strikes over the five-year period. The Navy's training and testing activities would occur over five years beginning in December 2018. On October 13, 2017, the Navy sent an amendment to its application and Navy's rulemaking/LOA application was considered final and complete. The Navy requests two five-year LOAs, one for training and one for testing activities to be conducted within the HSTT Study Area (which extends from the north-central Pacific Ocean, from the mean high tide line in Southern California west to Hawaii and the International Date Line), including the Hawaii and Southern California (SOCAL) Range Complexes, as well as the Silver Strand Training Complex and overlapping a small portion of the Point Mugu Sea Range. The Hawaii Range Complex encompasses ocean areas around the Hawaiian Islands, extending from 16 degrees north latitude to 43 degrees north latitude and from 150 degrees west longitude to the International Date Line. The SOCAL Range Complex is located approximately between Dana Point and San Diego, California, and extends southwest into the Pacific Ocean and also includes a small portion of the Point Mugu Sea Range. The Silver Strand Training Complex is an integrated set of training areas located on and adjacent to the Silver Strand, a narrow, sandy isthmus separating the San Diego Bay from the Pacific Ocean. Please refer to Figure 1-1 of the Navy's rulemaking/LOA application for a map of the HSTT Study Area, Figures 2-1 to 2-4 for the Hawaii Operating Area (where the majority of training and testing activities occur within the Hawaii Range Complex), Figures 2-5 to 2-7 for the SOCAL Range Complex, and Figure 2-8 for the Silver Strand Training Complex. The following types of training and testing, which are classified as military readiness activities pursuant to the MMPA, as amended by the 2004 NDAA, would be covered under the LOAs (if authorized): Amphibious warfare (in-water detonations), anti-submarine warfare (sonar and other transducers, in-water detonations), surface warfare (in-water detonations), mine warfare (sonar and other transducers, in-water detonations), and other warfare activities (sonar and other transducers, pile driving, air guns). This will be NMFS's third rulemaking (Hawaii and Southern California were separate rules in Phase I) for HSTT activities under the MMPA. NMFS published the first two rules for Phase I effective from January 5, 2009, through January 5, 2014, (74 FR 1456; on January 12, 2009) and effective January 14, 2009, through January 14, 2014 (74 FR 3882 on January 21, 2009) for Hawaii and Southern California, respectively. The rulemaking for Phase II (combined both Hawaii and Southern California) is applicable from December 24, 2013, through December 24, 2018 (78 FR 78106; on December 24, 2013). For this third rulemaking, the Navy is proposing to conduct similar activities as they have conducted over the past nine years under the previous rulemakings. Background of Request The Navy's mission is to organize, train, equip, and maintain combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas. This mission is mandated by Federal law (10 U.S.C. 5062), which ensures the readiness of the naval forces of the United States. The Navy executes this responsibility by training and testing at sea, often in designated operating areas (OPAREA) and testing and training ranges. The Navy must be able to access and utilize these areas and associated sea space and air space in order to develop and maintain skills for conducting naval activities. The Navy proposes to conduct training and testing activities within the HSTT Study Area. The Navy has been conducting similar military readiness activities in the Study Area since the 1940s. The tempo and types of training and testing activities have fluctuated because of the introduction of new technologies, the evolving nature of international events, advances in warfighting doctrine and procedures, and changes in force structure (organization of ships, weapons, and personnel). Such developments influence the frequency, duration, intensity, and location of required training and testing activities, but the basic nature of sonar and explosive events conducted in the HSTT Study Area has remained the same. The Navy's rulemaking/LOA application reflects the most up to date compilation of training and testing activities deemed necessary to accomplish military readiness requirements. The types and numbers of activities included in the proposed rule account for fluctuations in training and testing in order to meet evolving or emergent military readiness requirements. Description of the Specified Activity The Navy is requesting authorization to take marine mammals incidental to conducting training and testing activities. The Navy has determined that acoustic and explosives stressors are most likely to result in impacts on marine mammals that could rise to the level of harassment. Detailed descriptions of these activities are provided in the HSTT Draft Environmental Impact Statement (DEIS)/Overseas EIS (OEIS) (DEIS/OEIS) and in the Navy's rule making/LOA application (www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities) and are summarized here. Overview of Training and Testing Activities The Navy routinely trains and tests in the HSTT Study Area in preparation for national defense missions. Training and testing activities covered in the Navy's rulemaking/LOA application are briefly described below, and in more detail within Chapter 2 of the HSTT DEIS/ OEIS. Primary Mission Areas The Navy categorizes its activities into functional warfare areas called primary mission areas. These activities generally fall into the following seven primary mission areas: Air warfare; amphibious warfare; anti-submarine warfare (ASW); electronic warfare; expeditionary warfare; mine warfare (MIW); and surface warfare (SUW). Most activities addressed in the HSTT DEIS/OEIS are categorized under one of the primary mission areas; the testing community has three additional categories of activities for vessel evaluation, unmanned systems, and acoustic and oceanographic science and technology. Activities that do not fall within one of these areas are listed as ``other activities.'' Each warfare community (surface, subsurface, aviation, and special warfare) may train in some or all of these primary mission areas. The testing community also categorizes most, but not all, of its testing activities under these primary mission areas. The Navy describes and analyzes the impacts of its training and testing activities within the HSTT DEIS/OEIS and the Navy's rulemaking/ LOA application. In its assessment, the Navy concluded that sonar and other transducers, in-water detonations, air guns, and pile driving/ removal were the stressors that would result in impacts on marine mammals that could rise to the level of harassment (and serious injury or mortality by explosives or by vessel strike) as defined under the MMPA. The Navy's rulemaking/LOA application provides the Navy's assessment of potential effects from these stressors in [[Page 29874]] terms of the various warfare mission areas in which they would be conducted. In terms of Navy's primary warfare areas, this includes: Amphibious warfare (in-water detonations); ASW (sonar and other transducers, in-water detonations); SUW (in-water detonations); MIW (sonar and other transducers, in-water detonations); and Other warfare activities (sonar and other transducers, impact pile driving/vibratory removal, air guns). The Navy's training and testing activities in air warfare, electronic warfare, and expeditionary warfare do not involve sonar or other transducers, in-water detonations, pile driving/removal, air guns or any other stressors that could result in harassment, serious injury, or mortality of marine mammals. Therefore, activities in the air, electronic or expeditionary warfare areas are not discussed further in this proposed rule, but are analyzed fully in the Navy's HSTT DEIS/ OEIS. Amphibious Warfare The mission of amphibious warfare is to project military power from the sea to the shore (i.e., attack a threat on land by a military force embarked on ships) through the use of naval firepower and expeditionary landing forces. Amphibious warfare operations range from small unit reconnaissance or raid missions to large scale amphibious exercises involving multiple ships and aircraft combined into a strike group. Amphibious warfare training ranges from individual, crew, and small unit events to large task force exercises. Individual and crew training include amphibious vehicles and naval gunfire support training. Such training includes shore assaults, boat raids, airfield or port seizures, and reconnaissance. Large scale amphibious exercises involve ship-to-shore maneuver, naval fire support, such as shore bombardment, and air strike and attacks on targets that are in close proximity to friendly forces. Testing of guns, munitions, aircraft, ships, and amphibious vessels and vehicles used in amphibious warfare is often integrated into training activities and, in most cases, the systems are used in the same manner in which they are used for fleet training activities. Amphibious warfare tests, when integrated with training activities or conducted separately as full operational evaluations on existing amphibious vessels and vehicles following maintenance, repair, or modernization, may be conducted independently or in conjunction with other amphibious ship and aircraft activities. Testing is performed to ensure effective ship-to-shore coordination and transport of personnel, equipment, and supplies. Tests may also be conducted periodically on other systems, vessels, and aircraft intended for amphibious operations to assess operability and to investigate efficacy of new technologies. Anti-Submarine Warfare The mission of ASW is to locate, neutralize, and defeat hostile submarine forces that threaten Navy forces. ASW is based on the principle that surveillance and attack aircraft, ships, and submarines all search for hostile submarines. These forces operate together or independently to gain early warning and detection, and to localize, track, target, and attack submarine threats. ASW training addresses basic skills such as detecting and classifying submarines, as well as evaluating sounds to distinguish between enemy submarines and friendly submarines, ships, and marine life. More advanced training integrates the full spectrum of ASW from detecting and tracking a submarine to attacking a target using either exercise torpedoes (i.e., torpedoes that do not contain a warhead) or simulated weapons. These integrated ASW training exercises are conducted in coordinated, at-sea training events involving submarines, ships, and aircraft. Testing of ASW systems is conducted to develop new technologies and assess weapon performance and operability with new systems and platforms, such as unmanned systems. Testing uses ships, submarines, and aircraft to demonstrate capabilities of torpedoes, missiles, countermeasure systems, and underwater surveillance and communications systems. Tests may be conducted as part of a large-scale fleet training event involving submarines, ships, fixed-wing aircraft, and helicopters. These integrated training events offer opportunities to conduct research and acquisition activities and to train crews in the use of new or newly enhanced systems during a large-scale, complex exercise. Mine Warfare The mission of MIW is to detect, classify, and avoid or neutralize (disable) mines to protect Navy ships and submarines and to maintain free access to ports and shipping lanes. MIW also includes offensive mine laying to gain control of or deny the enemy access to sea space. Naval mines can be laid by ships, submarines, or aircraft. MIW neutralization training includes exercises in which ships, aircraft, submarines, underwater vehicles, unmanned vehicles, or marine mammal detection systems search for mine shapes. Personnel train to destroy or disable mines by attaching underwater explosives to or near the mine or using remotely operated vehicles to destroy the mine. Towed influence mine sweep systems mimic a particular ship's magnetic and acoustic signature, which would trigger a real mine causing it to explode. Testing and development of MIW systems is conducted to improve sonar, laser, and magnetic detectors intended to hunt, locate, and record the positions of mines for avoidance or subsequent neutralization. MIW testing and development falls into two primary categories: Mine detection or classification, and mine countermeasure and neutralization. Mine detection or classification testing involves the use of air, surface, and subsurface vessels and uses sonar, including towed and sidescan sonar, and unmanned vehicles to locate and identify objects underwater. Mine detection and classification systems are sometimes used in conjunction with a mine neutralization system. Mine countermeasure and neutralization testing includes the use of air, surface, and subsurface units to evaluate the effectiveness of detection systems, countermeasure and neutralization systems. Most neutralization tests use mine shapes, or non-explosive practice mines, to evaluate a new or enhanced capability. For example, during a mine neutralization test, a previously located mine is destroyed or rendered nonfunctional using a helicopter or manned/unmanned surface vehicle based system that may involve the deployment of a towed neutralization system. A small percentage of MIW tests require the use of high-explosive mines to evaluate and confirm the ability of the system or the crews conducting the training or testing to neutralize a high-explosive mine under operational conditions. The majority of MIW systems are deployed by ships, helicopters, and unmanned vehicles. Tests may also be conducted in support of scientific research to support these new technologies. Surface Warfare (SUW) The mission of SUW is to obtain control of sea space from which naval forces may operate, and conduct offensive action against other surface, subsurface, and air targets while also defending against enemy forces. In conducting SUW, aircraft use guns, air-launched cruise missiles, or other precision-guided munitions; ships employ torpedoes, naval guns, and [[Page 29875]] surface-to-surface missiles; and submarines attack surface ships using torpedoes or submarine-launched, anti-ship cruise missiles. SUW includes surface-to-surface gunnery and missile exercises; air-to- surface gunnery, bombing, and missile exercises; submarine missile or torpedo launch events, and the use of other munitions against surface targets. Testing of weapons used in SUW is conducted to develop new technologies and to assess weapon performance and operability with new systems and platforms, such as unmanned systems. Tests include various air-to-surface guns and missiles, surface-to-surface guns and missiles, and bombing tests. Testing events may be integrated into training activities to test aircraft or aircraft systems in the delivery of munitions on a surface target. In most cases the tested systems are used in the same manner in which they are used for fleet training activities. Other Warfare Activities Naval forces conduct additional training, testing and maintenance activities, which fall under other primary mission areas that are not listed above. The HSTT DEIS/OEIS combines these training and testing activities together in an ``other activities'' grouping for simplicity. These training and testing activities include, but are not limited to, sonar maintenance for ships and submarines, submarine navigation and under-ice certification, elevated causeway system (pile driving and removal), and acoustic and oceanographic research. These activities include the use of various sonar systems, impact pile driving/vibratory extraction, and air guns. Overview of Major Training Exercises and Other Exercises Within the HSTT Study Area A major training exercise (MTE) is comprised of several ``unit level'' range exercises conducted by several units operating together while commanded and controlled by a single commander. These exercises typically employ an exercise scenario developed to train and evaluate the strike group in naval tactical tasks. In an MTE, most of the activities being directed and coordinated by the strike group commander are identical in nature to the activities conducted during individual, crew, and smaller unit level training events. In an MTE, however, these disparate training tasks are conducted in concert, rather than in isolation. Some integrated or coordinated ASW exercises are similar in that they are comprised of several unit level exercises but are generally on a smaller scale than an MTE, are shorter in duration, use fewer assets, and use fewer hours of hull-mounted sonar per exercise. For the purpose of analysis, three key factors are used to identify and group major, integrated, and coordinated exercises including the scale of the exercise, duration of the exercise, and amount of hull-mounted sonar hours modeled/used for the exercise. NMFS considered the effects of all training exercises, not just these major, integrated, and coordinated training exercises in this proposed rule. Overview of Testing Activities Within the HSTT Study Area The Navy's research and acquisition community engages in a broad spectrum of testing activities in support of the fleet. These activities include, but are not limited to, basic and applied scientific research and technology development; testing, evaluation, and maintenance of systems (e.g., missiles, radar, and sonar) and platforms (e.g., surface ships, submarines, and aircraft); and acquisition of systems and platforms to support Navy missions and give a technological edge over adversaries. The individual commands within the research and acquisition community included in the Navy's rulemaking/LOA application are the Naval Air Systems Command, the Naval Sea Systems Command, the Office of Naval Research, and the Space and Naval Warfare Systems Command. Testing activities occur in response to emerging science or fleet operational needs. For example, future Navy experiments to develop a better understanding of ocean currents may be designed based on advancements made by non-government researchers not yet published in the scientific literature. Similarly, future but yet unknown Navy operations within a specific geographic area may require development of modified Navy assets to address local conditions. However, any evolving testing activities that would be covered under this rule would be expected to fall within the range of platforms, activities, sound sources, and other equipment described in this rule and to have impacts that fall within the range (i.e., nature and extent) of those covered within the rule. For example, the Navy identifies ``bins'' of sound sources to facilitate analyses--i.e., they identify frequency and source level bounds to a bin and then analyze the worst case scenario for that bin to understand the impacts of all of the sources that fall within a bin. While the Navy might be aware that sound source e.g., XYZ1 will definitely be used this year, sound source e.g., XYZ2 might evolve for testing three years from now, but if it falls within the bounds of the same sound source bin, it has been analyzed and any resulting take authorized. Some testing activities are similar to training activities conducted by the fleet. For example, both the fleet and the research and acquisition community fire torpedoes. While the firing of a torpedo might look identical to an observer, the difference is in the purpose of the firing. The fleet might fire the torpedo to practice the procedures for such a firing, whereas the research and acquisition community might be assessing a new torpedo guidance technology or testing it to ensure the torpedo meets performance specifications and operational requirements. Naval Air Systems Command Testing Activities Naval Air Systems Command testing activities generally fall in the primary mission areas used by the fleets. Naval Air Systems Command activities include, but are not limited to, the testing of new aircraft platforms (e.g., the F-35 Joint Strike Fighter aircraft), weapons, and systems (e.g., newly developed sonobuoys) that will ultimately be integrated into fleet training activities. In addition to the testing of new platforms, weapons, and systems, Naval Air Systems Command also conducts lot acceptance testing of weapons and systems, such as sonobuoys. Naval Sea Systems Command Testing Activities Naval Sea Systems Command activities are generally aligned with the primary mission areas used by the fleets. Additional activities include, but are not limited to, vessel evaluation, unmanned systems, and other testing activities. In the Navy's rulemaking/LOA application, for testing activities occurring at Navy shipyards and piers, only system testing is included. Testing activities are conducted throughout the life of a Navy ship, from construction through deactivation from the fleet, to verification of performance and mission capabilities. Activities include pierside and at-sea testing of ship systems, including sonar, acoustic countermeasures, radars, torpedoes, weapons, unmanned systems, and radio equipment; tests to determine how the ship performs at sea (sea trials); development and operational test and evaluation programs for new technologies and systems; and testing on all ships and systems that have undergone overhaul or maintenance. [[Page 29876]] Office of Naval Research Testing Activities As the Department of the Navy's science and technology provider, the Office of Naval Research provides technology solutions for Navy and Marine Corps needs. The Office of Naval Research's mission is to plan, foster, and encourage scientific research in recognition of its paramount importance as related to the maintenance of future naval power, and the preservation of national security. The Office of Naval Research manages the Navy's basic, applied, and advanced research to foster transition from science and technology to higher levels of research, development, test, and evaluation. The Office of Naval Research is also a parent organization for the Naval Research Laboratory, which operates as the Navy's corporate research laboratory and conducts a broad multidisciplinary program of scientific research and advanced technological development. Testing conducted by the Office of Naval Research in the HSTT Study Area includes acoustic and oceanographic research, large displacement unmanned underwater vehicle (an innovative naval prototype) research, and emerging mine countermeasure technology research. Space and Naval Warfare Systems Command Testing Activities Space and Naval Warfare Systems Command is the information warfare systems command for the U.S. Navy. The mission of the Space and Naval Warfare Systems Command is to acquire, develop, deliver, and sustain decision superiority for the warfighter. Space and Naval Warfare Systems Command Systems Center Pacific is the research and development part of Space and Naval Warfare Systems Command focused on developing and transitioning technologies in the area of command, control, communications, computers, intelligence, surveillance, and reconnaissance. Space and Naval Warfare Systems Command Systems Center Pacific conducts research, development, test, and evaluation projects to support emerging technologies for intelligence, surveillance, and reconnaissance; anti-terrorism and force protection; mine countermeasures; anti[hyphen]submarine warfare; oceanographic research; remote sensing; and communications. These activities include, but are not limited to, the testing of surface and subsurface vehicles; intelligence, surveillance, and reconnaissance/information operations sensor systems; underwater surveillance technologies; and underwater communications. The proposed training and testing activities were evaluated to identify specific components that could act as stressors (e.g., acoustic and explosive) by having direct or indirect impacts on the environment. This analysis included identification of the spatial variation of the identified stressors. Description of Acoustic and Explosive Stressors The Navy uses a variety of sensors, platforms, weapons, and other devices, including ones used to ensure the safety of Sailors and Marines, to meet its mission. Training and testing with these systems may introduce acoustic (sound) energy or shock waves from explosives into the environment. The Navy's rulemaking/LOA application describes specific components that could act as stressors by having direct or indirect impacts on the environment. This analysis includes identification of the spatial variation of the identified stressors. The following subsections describe the acoustic and explosive stressors for biological resources within the Study Area. Stressor/resource interactions that were determined to have de minimus or no impacts (i.e., vessel, aircraft, weapons noise, and explosions in air) were not carried forward for analysis in the Navy's rulemaking/LOA application. NMFS has reviewed the Navy's analysis and conclusions and finds them complete and supportable. Acoustic Stressors Acoustic stressors include acoustic signals emitted into the water for a specific purpose, such as sonar, other transducers (devices that convert energy from one form to another--in this case, to sound waves), and air guns, as well as incidental sources of broadband sound produced as a byproduct of impact pile driving and vibratory extraction. Explosives also produce broadband sound but are characterized separately from other acoustic sources due to their unique hazardous characteristics. Characteristics of each of these sound sources are described in the following sections. In order to better organize and facilitate the analysis of approximately 300 sources of underwater sound used for training and testing by the Navy, including sonars, other transducers, air guns, and explosives, a series of source classifications, or source bins, was developed. The source classification bins do not include the broadband sounds produced incidental to pile driving, vessel or aircraft transits, weapons firing and bow shocks. The use of source classification bins provides the following benefits: Provides the ability for new sensors or munitions to be covered under existing authorizations, as long as those sources fall within the parameters of a ``bin;'' improves efficiency of source utilization data collection and reporting requirements anticipated under the MMPA authorizations; ensures a conservative approach to all impact estimates, as all sources within a given class are modeled as the most impactful source (highest source level, longest duty cycle, or largest net explosive weight) within that bin; allows analyses to be conducted in a more efficient manner, without any compromise of analytical results; and provides a framework to support the reallocation of source usage (hours/explosives) between different source bins, as long as the total numbers of takes remain within the overall analyzed and authorized limits. This flexibility is required to support evolving Navy training and testing requirements, which are linked to real world events. Sonar and Other Transducers Active sonar and other transducers emit non-impulsive sound waves into the water to detect objects, safely navigate, and communicate. Passive sonars differ from active sound sources in that they do not emit acoustic signals; rather, they only receive acoustic information about the environment, or listen. In the Navy's rulemaking/LOA application, the terms sonar and other transducers are used to indicate active sound sources unless otherwise specified. The Navy employs a variety of sonars and other transducers to obtain and transmit information about the undersea environment. Some examples are mid-frequency hull-mounted sonars used to find and track enemy submarines; high-frequency small object detection sonars used to detect mines; high frequency underwater modems used to transfer data over short ranges; and extremely high-frequency (>200 kilohertz (kHz)) Doppler sonars used for navigation, like those used on commercial and private vessels. The characteristics of these sonars and other transducers, such as source level, beam width, directivity, and frequency, depend on the purpose of the source. Higher frequencies can carry more information or provide more information about objects off which they reflect, but attenuate more rapidly. Lower frequencies attenuate less rapidly, so may detect objects over a longer distance, but with less detail. Propagation of sound produced underwater is highly dependent on [[Page 29877]] environmental characteristics such as bathymetry, bottom type, water depth, temperature, and salinity. The sound received at a particular location will be different than near the source due to the interaction of many factors, including propagation loss; how the sound is reflected, refracted, or scattered; the potential for reverberation; and interference due to multi-path propagation. In addition, absorption greatly affects the distance over which higher-frequency sounds propagate. Because of the complexity of analyzing sound propagation in the ocean environment, the Navy relies on acoustic models in its environmental analyses that consider sound source characteristics and varying ocean conditions across the HSTT Study Area. The sound sources and platforms typically used in naval activities analyzed in the Navy's rulemaking/LOA application are described in Appendix A (Navy Activity Descriptions) of the HSTT DEIS/OEIS. The effects of these factors are explained in Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS. Sonars and other transducers used to obtain and transmit information underwater during Navy training and testing activities generally fall into several categories of use described below. Anti-Submarine Warfare Sonar used during ASW would impart the greatest amount of acoustic energy of any category of sonar and other transducers analyzed in the Navy's rulemaking/LOA application. Types of sonars used to detect enemy vessels include hull-mounted, towed, line array, sonobuoy, helicopter dipping, and torpedo sonars. In addition, acoustic targets and decoys (countermeasures) may be deployed to emulate the sound signatures of vessels or repeat received signals. Most ASW sonars are mid frequency (1-10 kHz) because mid-frequency sound balances sufficient resolution to identify targets with distance over which threats can be identified. However, some sources may use higher or lower frequencies. Duty cycles (the percentage of time acoustic energy is transmitted) can vary widely, from intermittently active to continuously active. For the duty cycle for the AN/SQS-53C, nominally they produce a 1-2 sec ping every 50-60 sec. Continuous active sonars often have substantially lower source levels but transmit the sonar signal much more frequently (greater than 80 percent of the time) when they are on. The beam width of ASW sonars can be wide- ranging in a search mode or highly directional in a track mode. Most ASW activities involving submarines or submarine targets would occur in waters greater than 600 feet (ft) deep due to safety concerns about running aground at shallower depths. Sonars used for ASW activities would typically be used in waters greater than 200 meters (m) which can vary from beyond three nautical miles (nmi) to 12 nmi or more from shore depending on local bathymetry. Exceptions include use of dipping sonar by helicopters, maintenance of vessel systems while in port, and system checks while vessels transit to or from port. Mine Warfare, Small Object Detection, and Imaging Sonars used to locate mines and other small objects, as well those used in imaging (e.g., for hull inspections or imaging of the seafloor), are typically high frequency or very high frequency. Higher frequencies allow for greater resolution but, due to their greater attenuation, are most effective over shorter distances. Mine detection sonar can be deployed (towed or vessel hull-mounted) at variable depths on moving platforms (ships, helicopters, or unmanned vehicles) to sweep a suspected mined area. Most hull-mounted anti-submarine sonars can also be used in an object detection mode known as ``Kingfisher'' mode. Sonars used for imaging are usually used in close proximity to the area of interest, such as pointing downward near the seafloor. Mine detection sonar use would be concentrated in areas where practice mines are deployed, typically in water depths less than 200 ft and at established minefields or temporary minefields close to strategic ports and harbors. Kingfisher mode on vessels is most likely to be used when transiting to and from port. Sound sources used for imaging could be used throughout the HSTT Study Area. Navigation and Safety Similar to commercial and private vessels, Navy vessels employ navigational acoustic devices including speed logs, Doppler sonars for ship positioning, and fathometers. These may be in use at any time for safe vessel operation. These sources are typically highly directional to obtain specific navigational data. Communication Sound sources used to transmit data (such as underwater modems), provide location (pingers), or send a single brief release signal to bottom-mounted devices (acoustic release) may be used throughout the HSTT Study Area. These sources typically have low duty cycles and are usually only used when it is desirable to send a detectable acoustic message. Classification of Sonar and Other Transducers Sonars and other transducers are grouped into classes that share an attribute, such as frequency range or purpose of use. Classes are further sorted by bins based on the frequency or bandwidth; source level; and, when warranted, the application in which the source would be used, as follows: Frequency of the non-impulsive acoustic source; [cir] Low-frequency sources operate below 1 kHz; [cir] Mid-frequency sources operate at and above 1 kHz, up to and including 10 kHz; [cir] High-frequency sources operate above 10 kHz, up to and including 100 kHz; [cir] Very high-frequency sources operate above 100 kHz but below 200 kHz; Sound pressure level of the non-impulsive source; [cir] Greater than 160 decibels (dB) re 1 micro Pascal ([mu]Pa), but less than 180 dB re 1 [mu]Pa; [cir] Equal to 180 dB re 1 [mu]Pa and up to 200 dB re 1 [mu]Pa; [cir] Greater than 200 dB re 1 [mu]Pa; Application in which the source would be used; [cir] Sources with similar functions that have similar characteristics, such as pulse length (duration of each pulse), beam pattern, and duty cycle. The bins used for classifying active sonars and transducers that are quantitatively analyzed in the HSTT Study Area are shown in Table 1 below. While general parameters or source characteristics are shown in the table, actual source parameters are classified. [[Page 29878]] Table 1--Sonar and Transducers Quantitatively Analyzed ------------------------------------------------------------------------ Source class category Bin Description ------------------------------------------------------------------------ Low-Frequency (LF): Sources LF3 LF sources greater that produce signals less than LF4 than 200 dB. 1 kHz. LF sources equal to 180 dB and up to 200 dB. LF5 LF sources less than 180 dB. LF6 LF sources greater than 200 dB with long pulse lengths. Mid-Frequency (MF): Tactical MF1 Hull-mounted surface and non-tactical sources that MF1K ship sonars (e.g., AN/ produce signals between 1-10 SQS-53C and AN/SQS- kHz. 60). Kingfisher mode associated with MF1 sonars. MF3 Hull-mounted submarine sonars (e.g., AN/BQQ- 10). MF4 Helicopter-deployed dipping sonars (e.g., AN/AQS-22). MF5 Active acoustic sonobuoys (e.g., DICASS). MF6 Active underwater sound signal devices (e.g., MK84). MF8 Active sources (greater than 200 dB) not otherwise binned. MF9 Active sources (equal to 180 dB and up to 200 dB) not otherwise binned. MF10 Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned. MF11 Hull-mounted surface ship sonars with an active duty cycle greater than 80%. MF12 Towed array surface ship sonars with an active duty cycle greater than 80%. MF14 Oceanographic MF sonar. High-Frequency (HF): Tactical HF1 Hull-mounted submarine and non-tactical sources that HF3 sonars (e.g., AN/BQQ- produce signals between 10-100 10). kHz. Other hull-mounted submarine sonars (classified). HF4 Mine detection, classification, and neutralization sonar (e.g., AQS-20). HF5 Active sources (greater than 200 dB) not otherwise binned. HF6 Active sources (equal to 180 dB and up to 200 dB) not otherwise binned. HF7 Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned. HF8 Hull-mounted surface ship sonars (e.g., AN/ SQS-61). Very High-Frequency Sonars VHF1 VHF sources greater (VHF): Non-tactical sources than 200 dB. that produce signals between 100-200 kHz. Anti-Submarine Warfare (ASW): ASW1 MF systems operating Tactical sources (e.g., active ASW2 above 200 dB. sonobuoys and acoustic counter- ASW3 MF Multistatic Active measures systems) used during Coherent sonobuoy ASW training and testing (e.g., AN/SSQ-125). activities. MF towed active acoustic countermeasure systems (e.g., AN/SLQ- 25). ASW4 MF expendable active acoustic device countermeasures (e.g., MK 3). ASW5 MF sonobuoys with high duty cycles. Torpedoes (TORP): Source TORP1 Lightweight torpedo classes associated with the TORP2 (e.g., MK 46, MK 54, active acoustic signals TORP3 or Anti-Torpedo produced by torpedoes. Torpedo). Heavyweight torpedo (e.g., MK 48). Heavyweight torpedo (e.g., MK 48). Forward Looking Sonar (FLS): FLS2 HF sources with short Forward or upward looking pulse lengths, narrow object avoidance sonars used beam widths, and for ship navigation and safety. focused beam patterns. Acoustic Modems (M): Systems M3 MF acoustic modems used to transmit data through (greater than 190 the water. dB). Swimmer Detection Sonars (SD): SD1-SD2 HF and VHF sources Systems used to detect divers with short pulse and submerged swimmers. lengths, used for the detection of swimmers and other objects for the purpose of port security. Synthetic Aperture Sonars SAS1 MF SAS systems. (SAS): Sonars in which active SAS2 HF SAS systems. acoustic signals are post- SAS3 VHF SAS systems. processed to form high- SAS4 MF to HF broadband resolution images of the mine countermeasure seafloor. sonar. Broadband Sound Sources (BB): BB1 MF to HF mine Sonar systems with large BB2 countermeasure sonar. frequency spectra, used for BB4 HF to VHF mine various purposes. BB5 countermeasure sonar. BB6 LF to MF oceanographic BB7 source. LF to MF oceanographic source. HF oceanographic source. LF oceanographic source. ------------------------------------------------------------------------ Notes: ASW: Antisubmarine Warfare; BB: Broadband Sound Sources; FLS: Forward Looking Sonar; HF: High-Frequency; LF: Low-Frequency; M: Acoustic Modems; MF: Mid-Frequency; SAS: Synthetic Aperture Sonars; SD: Swimmer Detection Sonars; TORP: Torpedoes; VHF: Very High- Frequency. Air Guns Air guns are essentially stainless steel tubes charged with high- pressure air via a compressor. An impulsive sound is generated when the air is almost instantaneously released into the surrounding water. Small air guns with capacities up to 60 cubic inches (in\3\) would be used during testing activities in various offshore areas of the Southern California Range Complex and in the Hawaii Range Complex. [[Page 29879]] Generated impulses would have short durations, typically a few hundred milliseconds, with dominant frequencies below 1 kHz. The root- mean-square sound pressure level (SPL) and peak pressure (SPL peak) at a distance 1 m from the air gun would be approximately 215 dB re 1 [mu]Pa and 227 dB re 1 [mu]Pa, respectively, if operated at the full capacity of 60 in\3\. The size of the air gun chamber can be adjusted, which would result in lower SPLs and sound exposure level (SEL) per shot. Pile Driving/Extraction Impact pile driving and vibratory pile removal would occur during construction of an Elevated Causeway System (ELCAS), a temporary pier that allows the offloading of ships in areas without a permanent port. Construction of the elevated causeway could occur in sandy shallow water coastal areas at Silver Strand Training Complex and at Camp Pendleton, both in the Southern California Range Complex. Installing piles for elevated causeways would involve the use of an impact hammer (impulsive) mechanism with both it and the pile held in place by a crane. The hammer rests on the pile, and the assemblage is then placed in position vertically on the beach or, when offshore, positioned with the pile in the water and resting on the seafloor. When the pile driving starts, the hammer part of the mechanism is raised up and allowed to fall, transferring energy to the top of the pile. The pile is thereby driven into the sediment by a repeated series of these hammer blows. Each blow results in an impulsive sound emanating from the length of the pile into the water column as well as from the bottom of the pile through the sediment. Because the impact wave travels through the steel pile at speeds faster than the speed of sound in water, a steep-fronted acoustic shock wave is formed in the water (note this shock wave has very low peak pressure compared to a shock wave from an explosive) (Reinhall and Dahl, 2011). An impact pile driver generally operates on average 35 blows per minute. Pile removal involves the use of vibratory extraction (non- impulsive), during which the vibratory hammer is suspended from the crane and attached to the top of a pile. The pile is then vibrated by hydraulic motors rotating eccentric weights in the mechanism, causing a rapid up and down vibration in the pile. This vibration causes the sediment particles in contact with the pile to lose frictional grip on the pile. The crane slowly lifts up on the vibratory driver and pile until the pile is free of the sediment. Vibratory removal creates continuous non-impulsive noise at low source levels for a short duration. The source levels of the noise produced by impact pile driving and vibratory pile removal from an actual ELCAS pile driving and removal are shown in Table 2. Table 2--Elevated Causeway System Pile Driving and Removal Underwater Sound Levels ---------------------------------------------------------------------------------------------------------------- Pile size and type Method Average sound levels at 10 m ---------------------------------------------------------------------------------------------------------------- 24-in. Steel Pipe Pile....... Impact 1........ 192 dB re 1 [mu]Pa SPL rms. 182 dB re 1 [mu]Pa\2\s SEL (single strike). 24-in. Steel Pipe Pile....... Vibratory 2..... 146 dB re 1 [mu]Pa SPL rms. 145 dB re 1 [mu]Pa\2\s SEL (per second of duration). ---------------------------------------------------------------------------------------------------------------- 1 Illingworth and Rodkin (2016). 2 Illingworth and Rodkin (2015). Notes: in = inch, SEL = Sound Exposure Level, SPL = Sound Pressure Level, rms = root mean squared, dB re 1 [mu]Pa = decibels referenced to 1 micropascal. In addition to underwater noise, the installation and removal of piles also results in airborne noise in the environment. Impact pile driving creates in-air impulsive sound about 100 dBA re 20 [mu]Pa at a range of 15 m (Illingworth and Rodkin, 2016). During vibratory extraction, the three aspects that generate airborne noise are the crane, the power plant, and the vibratory extractor. The average sound level recorded in air during vibratory extraction was about 85 dBA re 20 [mu]Pa (94 dB re 20 [mu]Pa) within a range of 10-15 m (Illingworth and Rodkin, 2015). The size of the pier and number of piles used in an ELCAS event is approximately 1,520 ft long, requiring 119 supporting piles. Construction of the ELCAS would involve intermittent impact pile driving over approximately 20 days. Crews work 24 hours (hrs) a day and would drive approximately 6 piles in that period. Each pile takes about 15 minutes to drive with time taken between piles to reposition the driver. When training events that use the ELCAS are complete, the structure would be removed using vibratory methods over approximately 10 days. Crews would remove about 12 piles per 24-hour period, each taking about 6 minutes to remove. Pile driving for ELCAS training would occur in shallower water, and sound could be transmitted on direct paths through the water, be reflected at the water surface or bottom, or travel through bottom substrate. Soft substrates such as sand bottom at the proposed ELCAS locations would absorb or attenuate the sound more readily than hard substrates (rock), which may reflect the acoustic wave. Most acoustic energy would be concentrated below 1,000 hertz (Hz) (Hildebrand, 2009). Explosive Stressors This section describes the characteristics of explosions during naval training and testing. The activities analyzed in the Navy's rulemaking/LOA application that use explosives are described in Appendix A (Navy Activity Descriptions) of the HSTT DEIS/OEIS. Explanations of the terminology and metrics used when describing explosives in the Navy's rulemaking/LOA application are also in Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS. The near-instantaneous rise from ambient to an extremely high peak pressure is what makes an explosive shock wave potentially damaging. Farther from an explosive, the peak pressures decay and the explosive waves propagate as an impulsive, broadband sound. Several parameters influence the effect of an explosive: The weight of the explosive warhead, the type of explosive material, the boundaries and characteristics of the propagation medium, and, in water, the detonation depth. The net explosive weight, the explosive power of a charge expressed as the equivalent weight of trinitrotoluene (TNT), accounts for the first two parameters. The effects of these factors are explained in Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS. [[Page 29880]] Explosions in Water Explosive detonations during training and testing activities are associated with high-explosive munitions, including, but not limited to, bombs, missiles, rockets, naval gun shells, torpedoes, mines, demolition charges, and explosive sonobuoys. Explosive detonations during training and testing involving the use of high-explosive munitions (including bombs, missiles, and naval gun shells), could occur in the air or at the water's surface. Explosive detonations associated with torpedoes and explosive sonobuoys could occur in the water column; mines and demolition charges could be detonated in the water column or on the ocean bottom. Most detonations would occur in waters greater than 200 ft in depth, and greater than 3 nmi from shore, although most mine warfare, demolition, and some testing detonations would occur in shallow water close to shore. Those that occur close to shore are typically conducted on designated ranges. In order to better organize and facilitate the analysis of explosives used by the Navy during training and testing that could detonate in water or at the water surface, explosive classification bins were developed. The use of explosive classification bins provides the same benefits as described for acoustic source classification bins in Section 1.4.1 (Acoustic Stressors) of the Navy's rulemaking/LOA application. Explosives detonated in water are binned by net explosive weight. The bins of explosives that are proposed for use in the Study Area are shown in Table 3 below. Table 3--Explosives Analyzed ------------------------------------------------------------------------ Net explosive weight Example explosive Bin 1 (lb) source ------------------------------------------------------------------------ E1.......................... 0.1-0.25............ Medium-caliber projectile. E2.......................... >0.25-0.5........... Medium-caliber projectile. E3.......................... >0.5-2.5............ Large-caliber projectile. E4.......................... >2.5-5.............. Mine neutralization charge. E5.......................... >5-10............... 5-inch projectile. E6.......................... >10-20.............. Hellfire missile. E7.......................... >20-60.............. Demo block/shaped charge. E8.......................... >60-100............. Light-weight torpedo. E9.......................... >100-250............ 500 lb. bomb. E10......................... >250-500............ Harpoon missile. E11......................... >500-650............ 650 lb. mine. E12......................... >650-1,000.......... 2,000 lb. bomb. E13 \2\..................... >1,000-1,740........ Mat weave. ------------------------------------------------------------------------ 1 Net Explosive Weight refers to the equivalent amount of TNT. 2 E13 is not modeled for protected species impacts in water because most energy is lost into the air or to the bottom substrate due to detonation in very shallow water. In addition, activities are confined to small cove without regular marine mammal occurrence. These are not single charges, but multiple smaller charges detonated simultaneously or within a short time period. Propagation of explosive pressure waves in water is highly dependent on environmental characteristics such as bathymetry, bottom type, water depth, temperature, and salinity, which affect how the pressure waves are reflected, refracted, or scattered; the potential for reverberation; and interference due to multi-path propagation. In addition, absorption greatly affects the distance over which higher frequency components of explosive broadband noise can propagate. Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS explains the characteristics of explosive detonations and how the above factors affect the propagation of explosive energy in the water. Because of the complexity of analyzing sound propagation in the ocean environment, the Navy relies on acoustic models in its environmental analyses that consider sound source characteristics and varying ocean conditions across the HSTT Study Area. Explosive Fragments Marine mammals could be exposed to fragments from underwater explosions associated with the specified activities. When explosive ordnance (e.g., bomb or missile) detonates, fragments of the weapon are thrown at high-velocity from the detonation point, which can injure or kill marine mammals if they are struck. These fragments may be of variable size and are ejected at supersonic speed from the detonation. The casing fragments will be ejected at velocities much greater than debris from any target due to the proximity of the casing to the explosive material. Risk of fragment injury reduces exponentially with distance as the fragment density is reduced. Fragments underwater tend to be larger than fragments produced by in-air explosions (Swisdak and Montaro, 1992). Underwater, the friction of the water would quickly slow these fragments to a point where they no longer pose a threat. Opposingly, the blast wave from an explosive detonation moves efficiently through the seawater. Because the ranges to mortality and injury due to exposure to the blast wave are likely to far exceed the zone where fragments could injure or kill an animal, the threshold are assumed to encompass risk due to fragmentation. Other Stressor--Vessel Strike There is a very small chance that a vessel utilized in training or testing activities could strike a large whale. Vessel strikes have the potential to result in incidental take from serious injury and/or mortality. Vessel strikes are not specific to any particular training or testing activity, but rather a limited, sporadic, and incidental result of Navy vessel movement within the Study Area. Vessel strikes from commercial, recreational, and military vessels are known to seriously injure and occasionally kill cetaceans (Abramson et al., 2011; Berman-Kowalewski et al., 2010; Calambokidis, 2012; Douglas et al., 2008; Laggner, 2009; Lammers et al., 2003; Van der Hoop et al., 2012; Van der Hoop et al., 2013), although reviews of the literature on ship strikes mainly involve collisions between commercial vessels and whales (Jensen and Silber, 2003; Laist et al., 2001). Vessel speed, size, and mass are all important factors in determining potential impacts of a vessel strike to marine mammals (Conn and Silber, 2013; Gende et al., 2011; Silber et al., 2010; Vanderlaan and Taggart, 2007; [[Page 29881]] Wiley et al., 2016). For large vessels, speed and angle of approach can influence the severity of a strike. The average speed of large Navy ships ranges between 10 and 15 knots (kn) and submarines generally operate at speeds in the range of 8-13 kn, while a few specialized vessels can travel at faster speeds. By comparison, this is slower than most commercial vessels where full speed for a container ship is typically 24 kn (Bonney and Leach, 2010). Additional information on Navy vessel movements is provided in the Specified Activities section. The Center for Naval Analysis conducted studies to determine traffic patterns of Navy and non-Navy vessels in the HSTT Study Area (Mintz, 2016; Mintz and Filadelfo, 2011; Mintz, 2012; Mintz and Parker, 2006). The most recent analysis covered the 5-year period from 2011 to 2015 for vessels over 65 ft in length (Mintz, 2016). Categories of vessels included in the study were U.S. Navy surface ship traffic and non-military civilian traffic such as cargo vessels, bulk carriers, commercial fishing vessels, oil tankers, passenger vessels, tugs, and research vessels (Mintz, 2016). In the Hawaii Range Complex, civilian commercial shipping comprised 89 percent of total vessel traffic while Navy ship traffic accounted for eight percent (Mintz, 2016). In the Southern California Range Complex civilian commercial shipping comprised 96 percent of total vessel traffic while Navy ship traffic accounted for four percent (Mintz, 2016). Navy ships transit at speeds that are optimal for fuel conservation or to meet training and testing requirements. Small craft (for purposes of this analysis, less than 18 m in length) have much more variable speeds (0-50+ kn, dependent on the activity). Submarines generally operate at speeds in the range of 8-13 kn. While these speeds are considered averages and representative of most events, some vessels need to operate outside of these parameters for certain times or during certain activities. For example, to produce the required relative wind speed over the flight deck, an aircraft carrier engaged in flight operations must adjust its speed through the water accordingly. Also, there are other instances such as launch and recovery of a small rigid hull inflatable boat; vessel boarding, search, and seizure training events; or retrieval of a target when vessels would be dead in the water or moving slowly ahead to maintain steerage. There are a few specific events, including high-speed tests of newly constructed vessels, where vessels would operate at higher speeds. Large Navy vessels (greater than 18 m in length) within the offshore areas of range complexes and testing ranges operate differently from commercial vessels in ways that may reduce potential whale collisions. Surface ships operated by or for the Navy have multiple personnel assigned to stand watch at all times, when a ship or surfaced submarine is moving through the water (underway). A primary duty of personnel standing watch on surface ships is to detect and report all objects and disturbances sighted in the water that may indicate a threat to the vessel and its crew, such as debris, a periscope, surfaced submarine, or surface disturbance. Per vessel safety requirements, personnel standing watch also report any marine mammals sighted in the path of the vessel as a standard collision avoidance procedure. All vessels proceed at a safe speed so they can take proper and effective action to avoid a collision with any sighted object or disturbance, and can be stopped within a distance appropriate to the prevailing circumstances and conditions. Specified Activities Proposed Training Activities The Navy's Specified Activities are presented and analyzed as a representative year of training to account for the natural fluctuation of training cycles and deployment schedules that generally influences the actual level of training that occurs year after year in any five- year period. Using a representative level of activity rather than a maximum tempo of training activity in every year is more reflective of the amount of hull-mounted mid-frequency active sonar estimated to be necessary to meet training requirements. It also means that the Navy is requesting fewer hours of hull-mounted mid-frequency active sonar. Both unit-level training and major training exercises have been adjusted to meet this representative year, as discussed below. For the purposes of the Navy's rulemaking/LOA application, the Navy assumes that some unit- level training would be conducted using synthetic means (e.g., simulators). Additionally, the Specified Activities analysis assumes that some unit-level active sonar training will be accounted for during the conduct of coordinated and major training exercises. The Optimized Fleet Response Plan and various training plans identify the number and duration of training cycles that could occur over a five-year period. The Specified Activities considers fluctuations in training cycles and deployment schedules that do not follow a traditional annual calendar but instead are influenced by in- theater demands and other external factors. Similar to unit-level training, the Specified Activities does not analyze a maximum number carrier strike group Composite Training Unit Exercises (one type of major exercise) every year, but instead assumes a maximum number of exercises would occur during two years of any five-year period and that a lower number of exercises would occur in the other 3 years (described in Estimate Take section). The training activities that the Navy proposes to conduct in the HSTT Study Area are summarized in Table 4. The table is organized according to primary mission areas and includes the activity name, associated stressors applicable to the Navy's rulemaking/LOA application, description of the activity, sound source bin, the locations of those activities in the HSTT Study Area, and the number of Specified Activities. For further information regarding the primary platform used (e.g., ship or aircraft type) see Appendix A (Navy Activity Descriptions) of the HSTT DEIS/OEIS. BILLING CODE 3510-22-P [[Page 29882]] [GRAPHIC] [TIFF OMITTED] TP26JN18.071 [[Page 29883]] [GRAPHIC] [TIFF OMITTED] TP26JN18.072 [[Page 29884]] [GRAPHIC] [TIFF OMITTED] TP26JN18.073 [[Page 29885]] [GRAPHIC] [TIFF OMITTED] TP26JN18.074 [[Page 29886]] [GRAPHIC] [TIFF OMITTED] TP26JN18.075 [[Page 29887]] [GRAPHIC] [TIFF OMITTED] TP26JN18.076 [[Page 29888]] [GRAPHIC] [TIFF OMITTED] TP26JN18.077 [[Page 29889]] [GRAPHIC] [TIFF OMITTED] TP26JN18.078 [[Page 29890]] [GRAPHIC] [TIFF OMITTED] TP26JN18.079 [[Page 29891]] [GRAPHIC] [TIFF OMITTED] TP26JN18.080 [[Page 29892]] Proposed Testing Activities Testing activities covered in the Navy's rulemaking/LOA application are described in Table 5 through Table 8. The five-year Specified Activities presented here is based on the level of testing activities anticipated to be conducted into the reasonably foreseeable future, with adjustments that account for changes in the types and tempo (increases or decreases) of testing activities to meet current and future military readiness requirements. The Specified Activities includes the testing of new platforms, systems, and related equipment that will be introduced after December 2018 and during the period of the rule. The majority of testing activities that would be conducted under the Specified Activities are the same or similar as those conducted currently or in the past. The Specified Activities includes the testing of some new systems using new technologies and takes into account inherent uncertainties in this type of testing. Under the Specified Activities, the Navy proposes a range of annual levels of testing that reflects the fluctuations in testing programs by recognizing that the maximum level of testing will not be conducted each year, but further indicates a five-year maximum for each activity that will not be exceeded. The Specified Activities contains a more realistic annual representation of activities, but includes years of a higher maximum amount of testing to account for these fluctuations. The tables include the activity name, associated stressor(s), description of the activity, sound source bin, the areas where the activity is conducted, and the number of activities per year and per five years. Not all sound sources are used with each activity. Under the ``Annual # of Activities'' column, activities show either a single number or a range of numbers to indicate the number of times that activity could occur during any single year. The ``5-Year # of Activities'' is the maximum times an activity would occur over the 5- year period of this request. More detailed activity descriptions can be found in the HSTT DEIS/OEIS. Naval Air Systems Command Table 5 summarizes the proposed testing activities for the Naval Air Systems Command analyzed within the HSTT Study Area. [[Page 29893]] [GRAPHIC] [TIFF OMITTED] TP26JN18.081 [[Page 29894]] [GRAPHIC] [TIFF OMITTED] TP26JN18.082 [[Page 29895]] [GRAPHIC] [TIFF OMITTED] TP26JN18.083 [[Page 29896]] Table 6 summarizes the proposed testing activities for the Naval Sea Systems Command analyzed within the HSTT Study Area. [GRAPHIC] [TIFF OMITTED] TP26JN18.084 [[Page 29897]] [GRAPHIC] [TIFF OMITTED] TP26JN18.085 [[Page 29898]] [GRAPHIC] [TIFF OMITTED] TP26JN18.086 [[Page 29899]] [GRAPHIC] [TIFF OMITTED] TP26JN18.087 Office of Naval Research Table 7 summarizes the proposed testing activities for the Office of Naval Research analyzed within the HSTT Study Area. [GRAPHIC] [TIFF OMITTED] TP26JN18.088 [[Page 29900]] Space and Naval Warfare Systems Command Table 8 summarizes the proposed testing activities for the Space and Naval Warfare Systems Command analyzed within the HSTT Study Area. [GRAPHIC] [TIFF OMITTED] TP26JN18.089 Summary of Acoustic and Explosive Sources Analyzed for Training and Testing Table 9 through Table 12 show the acoustic source classes and numbers, explosive source bins and numbers, air gun sources, and pile driving and removal activities associated with Navy training and testing activities in the HSTT Study Area that were analyzed in the Navy's rulemaking/LOA application. Table 9 shows the acoustic source classes (i.e., LF, MF, and HF) that could occur in any year under the Specified Activities for training and testing activities. Under the Specified Activities, acoustic source class use would vary annually, consistent with the number of annual activities summarized above. The five-year total for the Specified Activities takes into account that annual variability. [[Page 29901]] [GRAPHIC] [TIFF OMITTED] TP26JN18.090 [[Page 29902]] [GRAPHIC] [TIFF OMITTED] TP26JN18.091 [[Page 29903]] [GRAPHIC] [TIFF OMITTED] TP26JN18.092 [[Page 29904]] [GRAPHIC] [TIFF OMITTED] TP26JN18.093 BILLING CODE 3510-22-C Table 10 shows the number of air guns shots proposed in the HSTT Study Area for training and testing activities. Table 10--Training and Testing Air Gun Sources Quantitatively Analyzed in the HSTT Study Area -------------------------------------------------------------------------------------------------------------------------------------------------------- Training Testing Source class category Bin Unit \1\ ------------------------------------------------------------------- Annual 5-year total Annual 5-year total -------------------------------------------------------------------------------------------------------------------------------------------------------- Air Guns (AG): Small underwater air AG C 0 0 844 4,220 guns. -------------------------------------------------------------------------------------------------------------------------------------------------------- \1\ C = count. One count (C) of AG is equivalent to 100 air gun firings. Table 11 summarizes the impact pile driving and vibratory pile removal activities that would occur during a 24-hour period. Annually, for impact pile driving, the Navy will drive 119 piles, two times a year for a total of 238 piles. Over the 5-year period of the rule, the Navy will drive a total of 1190 piles by impact pile driving. Annually, for vibratory pile extraction, the Navy will extract 119 piles, two times a year for a total of 238 piles. Over the 5-year period of the rule, the Navy will extract a total of 1190 piles by vibratory pile extraction. Table 11--Summary of Pile Driving and Removal Activities per 24-Hour Period in the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Total estimated time Method Piles per 24- Time per pile of noise per hour period (minutes) 24-hour period (minutes) ---------------------------------------------------------------------------------------------------------------- Pile Driving (Impact)........................................... 6 15 90 Pile Removal (Vibratory)........................................ 12 6 72 ---------------------------------------------------------------------------------------------------------------- Table 12 shows the number of in-water explosives that could be used in any year under the Specified Activities for training and testing activities. Under the Specified Activities, bin use would vary annually, consistent with the number of annual activities summarized above. The five-year total for the Specified Activities takes into account that annual variability. [[Page 29905]] Table 12--Explosive Source Bins Analyzed and Numbers Used During Training and Testing Activities in the HSTT Study Area -------------------------------------------------------------------------------------------------------------------------------------------------------- Training Testing Net explosive Modeled underwater ----------------------------------------------------- Bin weight (lb) Example explosive source detonation depths (ft) \1\ 5-year 5-year Annual total Annual total -------------------------------------------------------------------------------------------------------------------------------------------------------- E1...................... 0.1-0.25 Medium-caliber projectiles. 0.3, 60.................... 2,940 14,700 8,916-15,216 62,880 E2...................... >0.25-0.5 Medium-caliber projectiles. 0.3, 50.................... 1,746 8,730 0 0 E3...................... >0.5-2.5 Large-caliber projectiles.. 0.3, 60.................... 2,797 13,985 2,880-3,124 14,844 E4...................... >2.5-5 Mine neutralization charge. 10, 16, 33, 50, 61, 65, 650 38 190 634-674 3,065 E5...................... >5-10 5 in projectiles........... 0.3, 10, 50................ 4,730-4,830 23,750 1,400 7,000 E6...................... >10-20 Hellfire missile........... 0.3, 10, 50, 60............ 592 2,872 26-38 166 E7...................... >20-60 Demo block/shaped charge... 10, 50, 60................. 13 65 0 0 E8...................... >60-100 Lightweight torpedo........ 0.3, 150................... 33-88 170 57 285 E9...................... >100-250 500 lb bomb................ 0.3........................ 410-450 2,090 4 20 E10..................... >250-500 Harpoon missile............ 0.3........................ 219-224 1,100 30 150 E11..................... >500-650 650 lb mine................ 61, 150.................... 7-17 45 12 60 E12..................... >650-1,000 2,000 lb bomb.............. 0.3........................ 16-21 77 0 0 E13..................... >1,000-1,740 Multiple Mat Weave charges. NA \2\..................... 9 45 0 0 -------------------------------------------------------------------------------------------------------------------------------------------------------- \1\ Net Explosive Weight refers to the amount of explosives; the actual weight of a munition may be larger due to other components. \2\ Not modeled because charge is detonated in surf zone; not a single E13 charge, but multiple smaller charges detonated in quick succession. Notes: in = inch(es), lb = pound(s), ft = feet. Vessel Movement Vessels used as part of the Specified Activities include ships, submarines, unmanned vessels, and boats ranging in size from small, 22 ft (7 m) rigid hull inflatable boats to aircraft carriers with lengths up to 1,092 ft (333 m). Large Navy ships greater than 60 ft (18 m) generally operate at speeds in the range of 10 to 15 kn for fuel conservation. Submarines generally operate at speeds in the range of 8 to 13 kn in transits and less than those speeds for certain tactical maneuvers. Small craft, less than 60 ft (18 m) in length, have much more variable speeds (dependent on the activity). Speeds generally range from 10 to 14 kn. While these speeds for large and small craft are representative of most events, some vessels need to temporarily operate outside of these parameters. The number of Navy vessels used in the HSTT Study Area varies based on military training and testing requirements, deployment schedules, annual budgets, and other unpredictable factors. Most training and testing activities involve the use of vessels. These activities could be widely dispersed throughout the HSTT Study Area, but would be typically conducted near naval ports, piers, and range areas. Navy vessel traffic would especially be concentrated near San Diego, California and Pearl Harbor, Hawaii. There is no seasonal differentiation in Navy vessel use. The majority of large vessel traffic occurs between the installations and the OPAREAS. Support craft would be more concentrated in the coastal waters in the areas of naval installations, ports and ranges. Activities involving vessel movements occur intermittently and are variable in duration, ranging from a few hours up to two weeks. Standard Operating Procedures For training and testing to be effective, personnel must be able to safely use their sensors and weapon systems as they are intended to be used in a real-world situation and to their optimum capabilities. While standard operating procedures are designed for the safety of personnel and equipment and to ensure the success of training and testing activities, their implementation often yields additional benefits to environmental, socioeconomic, public health and safety, and cultural resources. Navy standard operating procedures have been developed and refined over years of experience and are broadcast via numerous naval instructions and manuals, including, but not limited to: Ship, submarine, and aircraft safety manuals; Ship, submarine, and aircraft standard operating manuals; Fleet Area Control and Surveillance Facility range operating instructions; Fleet exercise publications and instructions; Naval Sea Systems Command test range safety and standard operating instructions; Navy instrumented range operating procedures; Naval shipyard sea trial agendas; Research, development, test, and evaluation plans; Naval gunfire safety instructions; Navy planned maintenance system instructions and requirements; Federal Aviation Administration regulations; and International Regulations for Preventing Collisions at Sea. Because standard operating procedures are essential to safety and mission success, the Navy considers them to be part of the Specified Activities, and has included them in the environmental analysis. Standard operating procedures that are recognized as providing a potential benefit to marine mammals during training and testing activities are noted below and discussed in more detail within the HSTT DEIS/OEIS. Vessel Safety Weapons Firing Safety Target Deployment Safety Towed In-Water Device Safety Pile Driving Safety Standard operating procedures (which are implemented regardless of their secondary benefits) are different from mitigation measures (which are designed entirely for the purpose of avoiding or reducing potential impacts on the environment). Refer to Section 1.5.5 Standing Operating Procedures of the Navy's rulemaking/LOA application for greater detail. Duration and Location Training and testing activities would be conducted in the HSTT Study Area throughout the year from 2018 through 2023 for the five-year period covered by the regulations. The HSTT Study Area (see Figure 1.1- 1 of the Navy's rulemaking/LOA application) is comprised of established operating and [[Page 29906]] warning areas across the north-central Pacific Ocean, from the mean high tide line in Southern California west to Hawaii and the International Date Line. The Study Area includes the at-sea areas of three existing range complexes (the Hawaii Range Complex, the SOCAL Range Complex, and the Silver Strand Training Complex), and overlaps a portion of the Point Mugu Sea Range (PMSR). Also included in the Study Area are Navy pierside locations in Hawaii and Southern California, Pearl Harbor, San Diego Bay, and the transit corridor \1\ on the high seas where sonar training and testing may occur. A Navy range complex consists of geographic areas that encompasses a water component (above and below the surface), airspace, and may encompass a land component where training and testing of military platforms, tactics, munitions, explosives, and electronic warfare systems occur. Range complexes include OPAREAs and special use airspace, which may be further divided to provide better control of the area and events being conducted for safety reasons. Please refer to the regional maps provided in the Navy's rulemaking/LOA application (Figures 2-1 through 2-8) for additional detail of the range complexes and testing ranges. The range complexes and testing ranges are described in the following sections. --------------------------------------------------------------------------- \1\ Vessel transit corridors are the routes typically used by Navy assets to traverse from one area to another. The route depicted in Figure 1-1 of the Navy's rulemaking/LOA application is the shortest route between Hawaii and Southern California, making it the quickest and most fuel efficient. Depicted vessel transit corridor is notional and may not represent the actual routes used by ships and submarines transiting from Southern California to Hawaii and back. Actual routes navigated are based on a number of factors including, but not limited to, weather, training, and operational requirements. --------------------------------------------------------------------------- Hawaii Range Complex The Hawaii Range Complex encompasses ocean areas located around the Hawaiian Islands chain. The ocean areas extend from 16 degrees north latitude to 43 degrees north latitude and from 150 degrees west longitude to the International Date Line, forming an area approximately 1,700 nmi by 1,600 nmi. The largest component of the Hawaii Range Complex is the Temporary OPAREA, extending north and west from the island of Kauai, and comprising over two million square nautical miles (nmi\2\) of air and sea space. The Temporary OPAREA is used primarily for missile testing by the Pacific Missile Range Facility (PMRF), and those missile tests are not part of the Navy's rulemaking/LOA application and are covered under other NEPA analysis. Other non-Navy entities such as various academic institutions and other Department of Defense agencies (DoD) such as the U.S. Air Force conduct activities in the PMRF. The PMRF activities referred to in the HSTT EIS/DEIS are very high altitude missile defense tests conducted by the Missile Defense Agency (MDA) (a non-Navy DoD command). For this rulemaking/LOA application, the area is used for Navy ship transits throughout the year. Despite the Temporary OPAREA's size, nearly all of the training and testing activities in the Hawaii Range Complex (HRC) take place within the smaller Hawaii OPAREA, that portion of the range complex immediately surrounding the island chain from Hawaii to Kauai (Figures 2-1 through 2-4 of the Navy's application). The Hawaii OPAREA consists of 235,000 nmi\2\ of special use airspace and ocean areas. The HRC includes over 115,000 nmi\2\ of combined special use airspace and air traffic control assigned airspace. As depicted in Figure 2-1 of the Navy's application, this airspace is almost entirely over the ocean and includes warning areas, air traffic controlled assigned airspace, and restricted areas. The Hawaii Range Complex includes the ocean areas as described above, as well as specific training areas around the islands of Kauai, Oahu, and Maui (Figures 2-2, 2-3, and 2-4 respectively of the Navy's application). The Hawaii Range Complex also includes the ocean portion of the PMRF on Kauai, which is both a fleet training range and a fleet and DoD testing range. The facility includes 1,100 nmi\2\ of instrumented ocean area at depths between 129 ft and 15,000 ft. The Hawaii Range Complex also includes the ocean areas around the designated Papahanaumokuakea Marine National Monument, referred hereafter as the Monument. Establishment of the Monument in June 2006 triggered a number of prohibitions on activities conducted in the Monument area. However, all military activities and exercises were specifically excluded from the listed prohibitions as long as the military exercises and activities are carried out in a manner that avoids, to the extent practicable and consistent with operational requirements, adverse impacts on monument resources and qualities. In 2016, the Monument was expanded from its original 139,818 square miles (mi\2\) to 582,578 mi\2\. The expansion of the Monument was primarily to the west--away from the portion of the Hawaii Range Complex where most training and testing activities are proposed to occur-- and retained the military exclusion language contained in the monument designation. Southern California Range Complex The SOCAL Range Complex is located between Dana Point and San Diego, and extends southwest into the Pacific Ocean (Figures 2-5, 2-6, and 2-7 of the Navy's application). Although the range complex extends more than 600 nmi beyond land, most activities occur with 200 nmi of Southern California. The two primary components of the SOCAL Range Complex are the ocean OPAREAs and the special use airspace. These components encompass 120,000 nmi\2\ of sea space and 113,000 nmi\2\ of special use airspace. Most of the special use airspace in the SOCAL Range Complex is defined by W-291 (Figure 2-5 of the Navy's application). This warning area extends vertically from the ocean surface to 80,000 ft above mean sea level and encompasses 113,000 nmi\2\ of airspace. The SOCAL Range Complex includes approximately 120,000 nmi\2\ of sea and undersea space, largely defined as that ocean area underlying the Southern California special use airspace described above. The SOCAL Range Complex also extends beyond this airspace to include the surface and subsurface area from the northeastern border of W-291 to the coast of San Diego County, and includes San Diego Bay. Point Mugu Sea Range Overlap A small portion (approximately 1,000 nmi\2\) of the Point Mugu Sea Range is included in the HSTT Study Area (Figure 2-5 of the Navy's application). Only that part of the Point Mugu Sea Range is used by the Navy for anti-submarine warfare training. This training uses sonar, is conducted in the course of major training exercises, and is analyzed in this request. Silver Strand Training Complex The Silver Strand Training Complex is an integrated set of training areas located on and adjacent to the Silver Strand, a narrow, sandy isthmus separating the San Diego Bay from the Pacific Ocean. It is divided into two non-contiguous areas: Silver Strand Training Complex- North and Silver Strand Training Complex-South (Figure 2-8 of the Navy's application). The Silver Strand Training Complex-North includes 10 oceanside boat training lanes (numbered as Boat Lanes 1-10), ocean anchorage areas (numbered 101-178), bayside water training areas (Alpha through Hotel), and the Lilly Ann drop zone. The boat training lanes are each 500 yards (yd) wide stretching 4,000 yd seaward and forming a 5,000 [[Page 29907]] yd long contiguous training area. The Silver Strand Training Complex- South includes four oceanside boat training lanes (numbered as Boat Lanes 11-14) and the TA-Kilo training area. The anchorages lie offshore of Coronado in the Pacific Ocean and overlap a portion of Boat Lanes 1-10. The anchorages are each 654 yd in diameter and are grouped together in an area located primarily due west of Silver Strand Training Complex-North, east of Zuniga Jetty and the restricted areas on approach to the San Diego Bay entrance. Ocean Operating Areas Outside the Bounds of Existing Range Complexes (Transit Corridor) In addition to the range complexes that are part of the Study Area, a transit corridor outside the boundaries of the range complexes is also included as part of the Study Area in the analysis. Although not part of any defined range complex, this transit corridor is important to the Navy in that it provides adequate air, sea, and undersea space in which vessels and aircraft conduct training and some sonar maintenance and testing while enroute between Southern California and Hawaii. The transit corridor, notionally defined by the great circle route (e.g., shortest distance) from San Diego to the center of the Hawaii Range Complex, as depicted in Figure 1-1 of the Navy's application, is generally used by ships transiting between the SOCAL Range Complex and Hawaii Range Complex. While in transit, ships and aircraft would, at times, conduct basic and routine unit level activities such as gunnery, bombing, and sonar training, testing, and maintenance, as long as the activities do not interfere with the primary objective of reaching their intended destination. Pierside Locations, Pearl Harbor, and San Diego Bay The Study Area includes select pierside locations where Navy surface ship and submarine sonar maintenance testing occur. For purposes of the Navy's application, pierside locations include channels and routes to and from Navy ports, and facilities associated with Navy ports and shipyards. These locations in the Study Area are located at Navy ports and naval shipyards in Pearl Harbor, Hawaii and in San Diego Bay, California (Figure 2-9 of the Navy's application). In addition, some training and testing activities occur throughout San Diego Bay. Description of Marine Mammals and Their Habitat in the Area of the Specified Activities Marine mammal species and their associated stocks that have the potential to occur in the HSTT Study Area are presented in Table 13 along with an abundance estimate, an associated coefficient of variation value, and best/minimum abundance estimates. The Navy proposes to take individuals of 39 marine mammal species by Level A and B harassment incidental to training and testing activities from the use of sonar and other transducers, in-water detonations, air guns, and impact pile driving/vibratory extraction activities. In addition, the Navy is requesting ten mortalities of two marine mammal stocks from explosives, and three takes of large whales by serious injury or mortality from vessel strikes over the five-year period. One marine mammal species, the Hawaiian monk seal, has critical habitat designated under the Endangered Species Act in the HSTT Study Area (described below). Information on the status, distribution, abundance, population trends, and ecology of marine mammals in the HSTT Study Area may be found in Chapter 4 of the Navy's rulemaking/LOA application. Additional information on the general biology and ecology of marine mammals are included in the HSTT DEIS/OEIS. In addition, NMFS annually publishes Stock Assessment Reports (SARs) for all marine mammals in U.S. Exclusive Economic Zone (EEZ) waters, including stocks that occur within the HSTT Study Area and are found specifically in the U.S. Pacific Marine Mammal SAR (Carretta et al., 2017) (see https://www.fisheries.noaa.gov/resource/document/us-pacific-marine-mammal-stock-assessments-2016). The species carried forward for analysis (and described in Table 13 below) are those likely to be found in the HSTT Study Area based on the most recent data available, and do not include stocks or species that may have once inhabited or transited the area but have not been sighted in recent years (e.g., species which were extirpated because of factors such as nineteenth and twentieth century commercial exploitation). Extralimital species, species that would not be considered part of the HSTT seasonal species assemblage (e.g., North Pacific right whale, any tropical odontocete species in SOCAL), were not included in the analysis. Table 13--Marine Mammals Occurrence Within the HSTT Study Area ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Status Common name Scientific name Stock -------------------------------------------- Occurrence Seasonal absence Stock abundance (CV)/ MMPA ESA minimum population ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Blue whale........................ Balaenoptera musculus Eastern North Depleted............ Endangered.......... Southern California. .................... 1,647 (0.07)/1,551 Pacific. Central North Depleted............ Endangered.......... Hawaii.............. Summer.............. 81 (1.14)/38 Pacific. Bryde's whale..................... Balaenoptera brydei/ Eastern Tropical .................... .................... Southern California. .................... unknown edeni. Pacific. Hawaiian............ Depleted............ .................... Hawaii.............. .................... 798 (0.28)/633 Fin whale......................... Balaenoptera physalus California, Oregon, Depleted............ Endangered.......... Southern California. .................... 9,029 (0.12)/8,127 and Washington. Hawaiian............ Depleted............ Endangered.......... Hawaii.............. Summer.............. 58 (1.12)/27 Gray whale........................ Eschrichtius robustus Eastern North .................... .................... Southern California. .................... 20,990 (0.05)/20,125 Pacific. Western North Depleted............ Endangered.......... Southern California. .................... 140 (0.04)/135 Pacific. Humpback whale.................... Megaptera California, Oregon, Depleted............ Threatened/ Southern California. .................... 1,918 (0.03)/1,876 novaeangliae. and Washington. Endangered \1\. Central North .................... .................... Hawaii.............. Summer.............. 10,103 (0.30)/7,890 Pacific. Minke whale....................... Balaenoptera California, Oregon, .................... .................... Southern California. .................... 636 (0.72)/369 acutorostrata. and Washington. Hawaiian............ .................... .................... Hawaii.............. Summer.............. unknown [[Page 29908]] Sei whale......................... Balaenoptera borealis Eastern North Depleted............ Endangered.......... Southern California. .................... 519 (0.4)/374 Pacific. Hawaii.............. Depleted............ Endangered.......... Hawaii.............. Summer.............. 178 (0.90)/93 Sperm whale....................... Physeter California, Oregon, Depleted............ Endangered.......... Southern California. .................... 2,106 (0.58)/1,332 macrocephalus. and Washington. Hawaiian............ Depleted............ Endangered.......... Hawaii.............. .................... 3,354 (0.34)/2,539 Pygmy sperm whale................. Kogia breviceps...... California, Oregon, .................... .................... Southern California. Winter and Fall..... 4,111 (1.12)/1,924 and Washington. Hawaiian............ .................... .................... Hawaii.............. .................... unknown Dwarf sperm whale................. Kogia sima........... California, Oregon, .................... .................... Southern California. .................... unknown and Washington. Hawaiian............ .................... .................... Hawaii.............. .................... unknown Baird's beaked whale.............. Berardius bairdii.... California, Oregon, .................... .................... Southern California. .................... 847 (0.81)/466 and Washington. Blainville's beaked whale......... Mesoplodon Hawaiian............ .................... .................... Hawaii.............. .................... 2,338 (1.13)/1,088 densirostris. Cuvier's beaked whale............. Ziphius cavirostris.. California, Oregon, .................... .................... Southern California. .................... 6,590 (0.55)/4,481 and Washington. Hawaiian............ .................... .................... Hawaii.............. .................... 1,941 na/1,142 Longman's beaked whale............ Indopacetus pacificus Hawaiian............ .................... .................... Hawaii.............. .................... 4,571 (0.65)/2,773 Mesoplodon beaked whales.......... Mesoplodon spp....... California, Oregon, .................... .................... Southern California. .................... 694 (0.65)/389 and Washington. Common Bottlenose dolphin......... Tursiops truncatus... California Coastal.. .................... .................... Southern California. .................... 453 (0.06)/346 California, Oregon, 1,924 (0.54)/1,255 and Washington Offshore. Hawaiian Pelagic.... .................... .................... Hawain.............. .................... 5,950 (0.59)/3,755 Kauai and Niihau.... .................... .................... Hawaii.............. .................... 184 (0.11)/168 Oahu................ .................... .................... Hawaii.............. .................... 743 (0.54)/485 4-Islands........... .................... .................... Hawaii.............. .................... 191 (0.24)/156 Hawaii Island....... .................... .................... Hawaii.............. .................... 128 (0.13)/115 False killer whale................ Pseudorca crassidens. Main Hawaiian Depleted............ Endangered.......... Hawaii.............. .................... 151 (0.20)/92 Islands Insular. Hawaii Pelagic...... .................... .................... Hawaii.............. .................... 1,540 (0.66)/928 Northwestern .................... .................... Hawaii.............. .................... 617 (1.11)/290 Hawaiian Islands. Fraser's dolphin.................. Lagenodelphis hosei.. Hawaiian............ .................... .................... Hawaii.............. .................... 16,992 (0.66)/10,241 Killer whale...................... Orcinus orca......... Eastern North .................... .................... Southern California. .................... 240 (0.49)/162 Pacific Offshore. Eastern North .................... .................... Southern California. .................... 243 unknown/243 Pacific Transient/ West Coast Transient \2\. Hawaiian............ .................... .................... Hawaii.............. .................... 101 (1.00)/50 Long-beaked common dolphin........ Delphinus capensis... California.......... .................... .................... Southern California. .................... 101,305 (0.49)/68,432 Melon-headed whale................ Peponocephala electra Hawaiian Islands.... .................... .................... Hawaii.............. .................... 5,794 (0.20)/4,904 Kohala Resident..... 447 (0.12)/404 Northern right whale dolphin...... Lissodelphis borealis California, Oregon, .................... .................... Southern California. .................... 26,556 (0.44)/18,608 and Washington. Pacific white-sided dolphin....... Lagenorhynchus California, Oregon, .................... .................... Southern California. .................... 26,814 (0.28)/21,195 obliquidens. and Washington. Pantropical spotted dolphin....... Stenella attenuata... Oahu................ .................... .................... Hawaii.............. .................... unknown 4-Islands........... unknown Hawaii Island....... .................... .................... Hawaii.............. .................... unknown Hawaii Pelagic...... .................... .................... Hawaii.............. .................... 15,917 (0.40)/11,508 Pygmy killer whale................ Feresa attenuata..... Tropical............ .................... .................... Southern California. Winter & Spring..... unknown Hawaiian............ .................... .................... Hawaii.............. .................... 3,433 (0.52)/2,274 Risso's dolphins.................. Grampus griseus...... California, Oregon, .................... .................... Southern California. .................... 6,336 (0.32)/4,817 and Washington. Hawaiian............ .................... .................... Hawaii.............. .................... 7,256 (0.41)/5,207 Rough-toothed dolphin............. Steno bredanensis.... na \3\.............. .................... .................... Southern California. .................... unknown Hawaiian............ .................... .................... Hawaii.............. .................... 6,288 (0.39)/4,581 [[Page 29909]] Short-beaked common dolphin....... Delphinus delphis.... California, Oregon, .................... .................... Southern California. .................... 969,861 (0.17)/839,325 and Washington. Short-finned pilot whale.......... Globicephala California, Oregon, .................... .................... Southern California. .................... 836 (0.79)/466 macrorhynchus. and Washington. Hawaiian............ .................... .................... Hawaii.............. .................... 12,422 (0.43)/8,782 Spinner dolphin................... Stenella longirostris Hawaii Pelagic...... .................... .................... Hawaii.............. .................... unknown Hawaii Island....... 631 (0.04)/585 Oahu and 4-Islands.. .................... .................... Hawaii.............. .................... 355 (0.09)/329 Kauai and Niihau.... .................... .................... Hawaii.............. .................... 601 (0)/509 Kure and Midway..... .................... .................... Hawaii.............. .................... unknown Pearl and Hermes.... .................... .................... Hawaii.............. .................... unknown Striped dolphin................... Stenella coeruleoalba California, Oregon, .................... .................... Southern California. .................... 29,211 (0.20)/24,782 and Washington. Hawaiian............ .................... .................... Hawaii.............. .................... 20,650 (0.36)/15,391 Dall's porpoise................... Phocoenoides dalli... California, Oregon, .................... .................... Southern California. .................... 25,750 (0.45)/17,954 and Washington. Harbor seal....................... Phoca vitulina....... California.......... .................... .................... Southern California. .................... 30,968 na/27,348 Hawaiian monk seal................ Neomonachus Hawaiian............ Depleted............ Endangered.......... Hawaii.............. .................... 1,272 na/1,205 schauinslandi. Northern elephant seal............ Mirounga California.......... .................... .................... Southern California. .................... 179,000 na/81,368 angustirostris. California sea lion............... Zalophus U.S. Stock.......... .................... .................... Southern California. .................... 296,750 na/153,337 californianus. Guadalupe fur seal................ Arctocephalus Mexico to California Depleted............ Threatened.......... Southern California. .................... 20,000 na/15,830 townsendi. Northern fur seal................. Callorhinus ursinus.. California.......... .................... .................... Southern California. .................... 14,050 na/7,524 ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Notes: \1\ The two humpback whale Distinct Population Segments making up the California, Oregon, and Washington stock present in Southern California are the Mexico Distinct Population Segment, listed under ESA as Threatened, and the Central America Distinct Population Segment, which is listed under ESA as Endangered. \2\ This stock is mentioned briefly in the Pacific Stock Assessment Report (Carretta et al., 2017) and referred to as the ``Eastern North Pacific Transient'' stock; however, the Alaska Stock Assessment Report contains assessments of all transient killer whale stocks in the Pacific and the Alaska Stock Assessment Report refers to this same stock as the ``West Coast Transient'' stock (Muto et al., 2017). \3\ Rough-toothed dolphin has a range known to include the waters off Southern California, but there is no recognized stock or data available for the U.S west coast. Below, we include additional information about the marine mammals in the area of the Specified Activities, where available, that will inform our analysis, such as identifying areas of important habitat or known behaviors, or where Unusual Mortality Events (UME) have been designated. Critical Habitat Currently there is one marine mammal, the ESA-listed Hawaiian monk seal, with designated critical habitat within the HSTT Study Area. However, critical habitat for ESA-listed Main Hawaiian Islands insular false killer whale was recently proposed in November 2017 (82 FR 51186; November 3, 2017), designating waters from the 45 m depth contour to the 3200 m depth contour around the main Hawaiian Islands from Niihau east to Hawaii. However, some areas were proposed for exclusion based on considerations of economic and national security impacts. Critical habitat for Hawaiian monk seals was designated in 1986 (51 FR 16047; April 30, 1986) and later revised in 1988 (53 FR 18988; May 26, 1988) and in 2015 (80 FR 50925; August 21, 2015) (NOAA, 2015a) (Figure 4-1 of the Navy's application). The essential features of the critical habitat were identified as: (1) Adjacent terrestrial and aquatic areas with characteristics preferred by monk seals for pupping and nursing; (2) shallow, sheltered aquatic areas adjacent to coastal locations preferred by monk seals for pupping and nursing; (3) marine areas from 0 to 500 m in depth preferred by juvenile and adult monk seals for foraging; (4) areas with low levels of anthropogenic disturbance; (5) marine areas with adequate prey quantity and quality; and (6) significant areas used by monk seals for hauling out, resting, or molting (NOAA, 2015a). In the Northwestern Hawaiian Islands Hawaiian monk seal critical habitat includes all beach areas, sand spits and islets, including all beach crest vegetation to its deepest extent inland as well as the seafloor and marine habitat 10 m in height above the seafloor from the shoreline out to the 200 m depth contour around Kure Atoll, Midway Atoll, Pearl and Hermes Reef, Lisianski Island, Laysan Island, Maro Reef, Gardner Pinnacles, French Frigate Shoals, Necker Island and Nihoa Island. In the main Hawaiian Islands, Hawaiian monk seal critical habitat includes the seafloor and marine habitat to 10 m above the seafloor from the 200 m depth contour through the shoreline and extending into terrestrial habitat 5 m inland from the shoreline between identified boundary points around Kaula Island (includes marine habitat only, some excluded areas see areas, Niihau (includes marine habitat from 10 m-200 m in depth; some excluded areas), Kauai, Oahu, Maui Nui (including Kahoolawe, Lanai, Maui, and Molokai), Hawaii. The approximate area encompassed by the Northwestern Hawaiian Islands was designated as the Papahanaumokuakea Monument in 2006, in part to protect the habitat of the Hawaiian monk seal. Hawaiian monk seals are managed as a single stock. There are six main reproductive subpopulations at: French Frigate Shoals, Laysan Island, Lisianski Island, [[Page 29910]] Pearl and Hermes Reef, Midway Island, and Kure Atoll in the northwestern Hawaiian Islands. Biologically Important Areas Biologically Important Areas (BIAs) include areas of known importance for reproduction, feeding, or migration, or areas where small and resident populations are known to occur (Van Parijs, 2015). Unlike critical habitat, these areas are not formally designated pursuant to any statute or law, but are a compilation of the best available science intended to inform impact and mitigation analyses. An interactive map of the BIAs may be found here: https://cetsound.noaa.gov/biologically-important-area-map. In Hawaii, 21 BIAs fall within or overlap with the HSTT Study Area. These include 11 small and resident population areas for species including dwarf sperm whales, Blainville's beaked whales, Cuvier's beaked whales, pygmy killer whales, short-finned pilot whales, melon- headed whales, false killer whales, pantropical spotted dolphins, spinner dolphins, rough-toothed dolphins, and common bottlenose dolphins (see Appendix K of the HSTT DEIS/OEIS for figures depicting these areas). In addition, six non-contiguous areas located adjacent to the eight main Hawaiian Islands have been designated as a humpback whale reproductive BIA (Baird et al., 2015c). Five of the 28 BIAs that were identified for four species off the U.S. west coast (Calambokidis et al., 2015a) are located within or overlapping the SOCAL portion of the Study Area (see Appendix K of the HSTT DEIS/OEIS for figures depicting these areas). These identified areas include four feeding areas for blue whales and a migration area for gray whales (Calambokidis et al., 2015a). Main Hawaiian Islands Humpback Whale Reproduction BIA A single biologically important area around and between portions of eight islands was identified for breeding humpback whales in the Main Hawaiian Islands from December through April (Baird et al., 2015a) (see Figure K.3-1 of the HSTT DEIS/OEIS). The Main Hawaiian Islands Humpback Whale Reproduction BIA contains several humpback whale breeding sub- areas off the coasts of Kauai, Niihau, Oahu, Maui, and Hawaii Island. The highest densities of whales occur in waters that are less than 200 m in depth. The Main Hawaiian Islands Humpback Whale Reproduction Area also overlaps the Navy's 4-Islands Region and Hawaii Island Mitigation Areas and Humpback Whale Special Reporting Areas described later in this document (and also shown in Appendix K of the HSTT DEIS/OEIS). The Main Hawaiian Islands Humpback Whale Reproduction BIA also encompasses the entire Humpback Whale National Marine Sanctuary. Dwarf Sperm Whales Small and Resident Population A year-round BIA has been identified for a small resident population of dwarf sperm whales located off the island of Hawaii (Mahaffy et al., 2009; Baird et al., 2013a) with sightings between 500 and 1,000 m in depth (Baird et al., 2013a). This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document. Blainville's Beaked Whales Small and Resident Population A year-round BIA for a small resident population of Blainville's beaked whales has been identified off the island of Hawaii (McSweeney et al., 2007; Schorr et al., 2009a) with the highest density of groups in water between 500 and 1,500 m in depth, and density decreasing offshore (Baird et al., 2015c). This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document. Cuvier's Beaked Whales Small and Resident Population A year-round BIA for a small resident population of Cuvier's beaked whales has been identified off the island of Hawaii with the highest density of groups in water between 1,500 and 4,000 m in depth, and density decreasing offshore (Baird et al., 2015c). This BIA also mostly overlaps the Navy's Hawaii Island Mitigation Area described later in this document. Pygmy Killer Whales Small and Resident Population A year-round BIA for a small resident population of pygmy killer whales has been identified for the Hawaii Island resident population. This BIA includes the west side of the island of Hawaii, from northwest of Kawaihae south to the south point of the island, and along the southeast coast of the island. This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document. Short-Finned Pilot Whales Small and Resident Population A year- round BIA for a small resident population of short-finned pilot whales has been identified off the island of Hawaii (Baird et al., 2011c, 2013a; Mahaffy, 2012). Short-finned pilot whales are primarily connected to slope habitats off the islands, with the highest density between 1,000 and 2,500 m in depth, dropping off significantly after 2,500 m (Baird et al., 2013a). This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document. Melon-Headed Whales Small and Resident Population A year-round BIA has been identified for a small and resident population of melon-headed whales off the island of Hawaii, primarily using the Kohala area. This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document. False Killer Whales Small and Resident Population A year-round BIA has been identified for a small and resident insular population of false killer whales off the coasts of Oahu, Maui, Molokai, Lanai, and Hawaii Island. The known range of this population extends from west of Niihau to east of Hawaii, out to 122 km offshore (Baird et al., 2012). This BIA also partially overlap the Navy's 4- Islands Region and Hawaii Island Mitigation Areas described later in this document. Pantropical Spotted Dolphins Small and Resident Populations Three year-round BIAs have been identified for small and resident populations of pantropical spotted dolphin. Three stocks of this species occurs around the main Hawaiian Islands (Oahu, the 4-Island Region, and off the main island of Hawaii). Two of these BIAs also overlap the Navy's 4-Islands Region and Hawaii Island Mitigation Areas described later in this document. Spinner Dolphins Small and Resident Populations Year-round BIAs have been identified for five small and resident populations of spinner dolphins. The boundaries of these populations are out to 10 nmi from shore around Kure and Midway Atolls, Pearl and Hermes Reef, Kauai and Niihau, Oahu and the 4-Islands Region and off the main island of Hawaii (Carretta et al., 2014). Two of these BIAs also overlap the Navy's 4-Islands Region and Hawaii Island Mitigation Areas described later in this document. Rough-Toothed Dolphins Small and Resident Population A year-round BIA has been identified for a small demographically isolated resident population off the island of Hawaii (Baird et al., 2008a; Albertson, [[Page 29911]] 2015). This species is also found elsewhere among the Hawaiian Islands. The Navy's Hawaii Island Mitigation Area also overlaps with the majority of this BIA described later in this document. Common Bottlenose Dolphins Small and Resident Populations Year-round BIAs have been identified for the four insular stocks of bottlenose dolphins in Hawaiian waters. They are found both nearshore and offshore areas (Barlow, 2006), but around the main Hawaiian Islands they are primarily found in depths of less than 1,000 m (Baird et al., 2013a). The Navy's 4-Islands Region Mitigation Area overlaps portions of the BIA off of Molokai, Maui, and Lanai and the Hawaii Island Mitigation Area (described later in this document) includes the entire BIA off of the Island of Hawaii. Blue Whale Feeding BIAs There are nine feeding area BIAs identified for blue whales off the U.S. west coast (Calambokidis et al., 2015a), but only four overlap with the SOCAL portion of the HSTT Study Area (see Figure K.4-1 of the HSTT DEIS/OEIS). Two of these feeding areas (the Santa Monica Bay to Long Beach and the San Nicolas Island feeding area BIAs) are at the extreme northern edge and slightly overlap with the SOCAL portion of the HSTT Study Area. The remaining two feeding areas (the Tanner-Cortes Bank and the San Diego feeding area BIAs) are entirely within the SOCAL portion of the HSTT Study Area (Calambokidis et al., 2015a). The feeding behavior for which these areas are designated occurs from June to October (Aquatic Mammals, 2015; Calambokidis et al., 2015a). The San Diego blue whale feeding area overlaps with the Navy's San Diego Arc Mitigation Area as described later in this document. Gray Whale Migration BIA Calambokidis et al. (2015) identified a gray whale migration area off Southern California and overlapping with all the Southern California portion of the HSTT Study Area north of the border with Mexico (Figure K.4-7). This migration area covers approximately 22,300 km \2\ of water space within the HSTT Study Area. National Marine Sanctuaries Under Title III of the Marine Protection, Research, and Sanctuaries Act of 1972 (also known as the National Marine Sanctuaries Act (NMSA)), NOAA can establish as national marine sanctuaries (NMS), areas of the marine environment with special conservation, recreational, ecological, historical, cultural, archaeological, scientific, educational, or aesthetic qualities. Sanctuary regulations prohibit destroying, causing the loss of, or injuring any sanctuary resource managed under the law or regulations for that sanctuary (15 CFR part 922). NMS are managed on a site-specific basis, and each sanctuary has site-specific regulations. Most, but not all sanctuaries have site-specific regulatory exemptions from the prohibitions for certain military activities. Separately, section 304(d) of the NMSA requires Federal agencies to consult with the Office of National Marine Sanctuaries whenever their Specified Activities are likely to destroy, cause the loss of, or injure a sanctuary resource. There are two national marine sanctuaries managed by the Office of National Marine Sanctuaries within the Study Area, the Hawaiian Islands Humpback Whale NMS and Channel Islands NMS (see Table 6.1-2 and Figures 6.1-3 and 6.1-4 of the HSTT DEIS/OEIS), which are described below. Hawaiian Islands Humpback Whale NMS The Hawaiian Islands Humpback Whale NMS is a single-species managed sanctuary, composed of 1,035 nmi\2\ of the waters around Maui, Lanai, and Molokai; and smaller areas off the north shore of Kauai, off Hawaii's west coast, and off the north and southeast coasts of Oahu. The Sanctuary is entirely within the HRC of the HSTT Study Area and constitutes one of the world's most important Hawaii humpback whale Distinct Population Segment (DPS) habitats (81 FR 62259; September 8, 2016), and is a primary region for humpback reproduction in the United States (National Marine Sanctuaries Program, 2002). Scientists estimate that more than 50 percent of the entire North Pacific humpback whale population migrates to Hawaiian waters each winter to mate, calve, and nurse their young. The North Pacific humpback whale population has been split into two DPSs. The Hawaii humpback whale DPS migrates to Hawaiian waters each winter and is not listed under the ESA. In addition to protection under the MMPA, the Hawaii humpback whale DPS is protected in sanctuary waters by the Hawaiian Islands NMS. The sanctuary was created to protect humpback whales and shallow, protected waters important for calving and nursing (Office of National Marine Sanctuaries, 2010). The Hawaiian Islands Humpback Whale NMS overlaps with the Main Hawaiian Islands Humpback Whale Reproduction Area (BIA) identified in Van Parijs (2015) and Baird et al. (2015) (shown in Figure K.3-1 of Appendix K and as discussed in Appendix K, Section K.3.1 (Main Hawaiian Islands Humpback Whale Reproduction Area of the HSTT DEIS/OEIS)). Channel Islands NMS The Channel Islands NMS is an ecosystem-based managed sanctuary consisting of an area of 1,109 nmi \2\ around Anacapa Island, Santa Cruz Island, Santa Rosa Island, San Miguel Island, and Santa Barbara Island to the south. Only 92 nmi \2\, or about 8 percent of the sanctuary, occurs within the SOCAL portion of the Study Area (see Figure 6.1-4 of the HSTT DEIS/OEIS). The Study Area overlaps with the sanctuary at Santa Barbara Island. In addition, the Navy has proposed to implement the Santa Barbara Island Mitigation Area around Santa Barbara Island out to 6 nmi as described later in this document (also see Section K.2.2, Mitigation Areas to be Implemented of the HSTT DEIS/ OEIS). As an ecosystem-based managed sanctuary, key habitats include kelp forest, surfgrass and eelgrass, intertidal zone, nearshore subtidal, deepwater benthic, and water column habitat. The diversity of habitats onshore and offshore contributes to the high species diversity in the Channel Islands NMS, with more than 195 species of birds, at least 33 species of cetaceans, 4 species of sea turtles, at least 492 species of algae and 4 species of sea grasses, a variety of invertebrates (including two endangered species (black abalone and the white abalone)), and 481 species of fish (NMS, 2009b). Unusual Mortality Events (UME) A UME is defined under Section 410(6) of the MMPA as a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response. From 1991 to the present, there have been 16 formally recognized UMEs affecting marine mammals in California and Hawaii and involving species under NMFS's jurisdiction. Two UMEs that could be relevant to informing the current analysis are discussed below. Specifically, the California sea lion UME in California is still open, but will be closed soon. The Guadalupe fur seal UME in California is still active and involves an ongoing investigation. California Sea Lion UME Elevated strandings of California sea lion pups began in Southern California in January 2013. In 2013, over 1,600 California sea lions stranded alive along the Southern California coastline and [[Page 29912]] over 3,500 live stranded California sea lions stranded on beaches in 2015, which was the highest number on record. Approximately 13,000 California sea lions (both live and dead) stranded from January 1, 2013, through December 31, 2017. Strandings in 2017 have finally returned to baseline (approximately 1,400/yr). The UME is currently defined to include pup and yearling California sea lions (0-2 years of age). Many of the sea lions were emaciated, dehydrated, and very underweight for their age. Findings to date indicate that a likely contributor to the large number of stranded, malnourished pups was a change in the availability of sea lion prey, especially sardines, a high value food source for both weaned pups and nursing mothers. Current data show changes in availability of sea lion prey in Southern California waters was likely a contributor to the UME, and this change was most likely secondary to ecological factors (El Ni[ntilde]o and Warm Water Blob). Sardine spawning grounds shifted further offshore in 2012 and 2013, and while other prey were available (market squid and rockfish), these may not have provided adequate nutrition in the milk of sea lion mothers supporting pups or for newly-weaned pups foraging on their own. Although the pups showed signs of some viruses and infections, findings indicate that this event was not caused by disease, but rather by the lack of high quality, close-by food sources for nursing mothers and weaned pups. Current evidence does not support that this UME was caused by a single infectious agent, though a variety of disease-causing bacteria and viruses were found in samples from sea lion pups. This investigation will soon be closed. Please refer to https://www.fisheries.noaa.gov/national/marine-life-distress/2013-2017-california-sea-lion-unusual-mortality-event-california for more information on this UME. Guadalupe Fur Seal UME Increased strandings of Guadalupe fur seals began along the entire coast of California in January 2015 and were eight times higher than the historical average (approximately 10 seals/yr). Strandings have continued since 2015 and have remained well above average through 2017. As of March 8, 2018, the total number of Guadalupe fur seals to date in the UME is 241. Strandings are seasonal and generally peak in April through June of each year. The Guadalupe fur seal strandings have been mostly weaned pups and juveniles (1-2 years old) with both live and dead strandings occurring. Current findings from the majority of stranded animals include primary malnutrition with secondary bacterial and parasitic infections. This UME is occurring in the same area as the ongoing 2013-2017 California sea lion UME. This investigation is ongoing. Please refer to https://www.fisheries.noaa.gov/national/marine-life-distress/2015-2018-guadalupe-fur-seal-unusual-mortality-event-california for more information on this UME. Marine Mammal Hearing Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities (e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes (i.e., low-frequency cetaceans). Subsequently, NMFS (2016) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 dB threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. The functional groups and the associated frequencies are indicated below (note that these frequency ranges correspond to the range for the composite group, with the entire range not necessarily reflecting the capabilities of every species within that group): Low-frequency cetaceans (mysticetes): Generalized hearing is estimated to occur between approximately 7 Hz and 35 kHz; Mid-frequency cetaceans (larger toothed whales, beaked whales, and most delphinids): Generalized hearing is estimated to occur between approximately 150 Hz and 160 kHz; High-frequency cetaceans (porpoises, river dolphins, and members of the genera Kogia and Cephalorhynchus; including two members of the genus Lagenorhynchus, on the basis of recent echolocation data and genetic data): Generalized hearing is estimated to occur between approximately 275 Hz and 160 kHz; Pinnipeds in water; Phocidae (true seals): Generalized hearing is estimated to occur between approximately 50 Hz to 86 kHz; and Pinnipeds in water; Otariidae (eared seals): Generalized hearing is estimated to occur between 60 Hz and 39 kHz. The pinniped functional hearing group was modified from Southall et al. (2007) on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range (Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 2013). For more detail concerning these groups and associated frequency ranges, please see NMFS (2016) for a review of available information. Potential Effects of Specified Activities on Marine Mammals and Their Habitat This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The ``Estimated Take of Marine Mammals'' section later in this document includes a quantitative analysis of the number of instances of take that could occur from these activities. The ``Negligible Impact Analysis and Determination'' section considers the content of this section, the ``Estimated Take of Marine Mammals'' section, and the ``Proposed Mitigation'' section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks. The Navy has requested authorization for the take of marine mammals that may occur incidental to training and testing activities in the HSTT Study Area. The Navy analyzed potential impacts to marine mammals from acoustic and explosive sources as well as vessel strikes. Other potential impacts to marine mammals from training and testing activities in the HSTT Study Area were analyzed in the HSTT DEIS/OEIS, in consultation with NMFS as a cooperating agency, and determined to be unlikely to result in marine mammal take. Therefore, the Navy has not requested authorization for take of marine mammals incidental to other components of their Specified Activities, and we agree that take is [[Page 29913]] unlikely to occur from those components. In this proposed rule, NMFS analyzes the potential effects on marine mammals from the activity components that may cause the take of marine mammals: Exposure to acoustic or explosive stressors including non-impulsive (sonar and other active acoustic sources) and impulsive (explosives, impact pile driving, and air guns) stressors, and vessel strikes. For the purpose of MMPA incidental take authorizations, NMFS's effects assessments serve four primary purposes: (1) To prescribe the permissible methods of taking (i.e., Level B harassment (behavioral harassment and temporary threshold shift (TTS), Level A harassment (permanent threshold shift (PTS) or non-auditory injury), serious injury, or mortality, including an identification of the number and types of take that could occur by harassment, serious injury, or mortality) and to prescribe other means of effecting the least practicable adverse impact on such species or stock and its habitat (i.e., mitigation); (2) to determine whether the specified activities would have a negligible impact on the affected species or stocks of marine mammals (based on the likelihood that the activities would adversely affect the species or stock through effects on annual rates of recruitment or survival); (3) to determine whether the specified activities would have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (however, there are no subsistence communities that would be affected in the HSTT Study Area, so this determination is inapplicable to the HSTT rulemaking); and (4) to prescribe requirements pertaining to monitoring and reporting. In the Potential Effects Section, NMFS provides a general description of the ways marine mammals may be affected by these activities in the form of mortality, physical trauma, sensory impairment (permanent and temporary threshold shifts and acoustic masking), physiological responses (particular stress responses), behavioral disturbance, or habitat effects. Explosives and vessel strikes, which have the potential to result in incidental take from serious injury and/or mortality, will be discussed in more detail in the Estimated Take of Marine Mammals section. The Estimated Take of Marine Mammals section also discusses how the potential effects on marine mammals from non-impulsive and impulsive sources relate to the MMPA definitions of Level A and Level B Harassment, and quantifies those effects that rise to the level of a take along with the potential effects from vessel strikes. The Negligible Impact Analysis Section assesses whether the proposed authorized take will have a negligible impact on the affected species and stocks. Potential Effects of Underwater Sound Note that, in the following discussion, we refer in many cases to a review article concerning studies of noise-induced hearing loss conducted from 1996-2015 (i.e., Finneran, 2015). For study-specific citations, please see that work. Anthropogenic sounds cover a broad range of frequencies and sound levels and can have a range of highly variable impacts on marine life, from none or minor to potentially severe responses, depending on received levels, duration of exposure, behavioral context, and various other factors. The potential effects of underwater sound from active acoustic sources can possibly result in one or more of the following: temporary or permanent hearing impairment, non-auditory physical or physiological effects, behavioral disturbance, stress, and masking (Richardson et al., 1995; Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007; G[ouml]tz et al., 2009). The degree of effect is intrinsically related to the signal characteristics, received level, distance from the source, and duration of the sound exposure. In general, sudden, high level sounds can cause hearing loss, as can longer exposures to lower level sounds. Temporary or permanent loss of hearing will occur almost exclusively for noise within an animal's hearing range. We first describe specific manifestations of acoustic effects before providing discussion specific to the Navy's activities. Richardson et al. (1995) described zones of increasing intensity of effect that might be expected to occur, in relation to distance from a source and assuming that the signal is within an animal's hearing range. First is the area within which the acoustic signal would be audible (potentially perceived) to the animal, but not strong enough to elicit any overt behavioral or physiological response. The next zone corresponds with the area where the signal is audible to the animal and of sufficient intensity to elicit behavioral or physiological responsiveness. Third is a zone within which, for signals of high intensity, the received level is sufficient to potentially cause discomfort or tissue damage to auditory systems. Overlaying these zones to a certain extent is the area within which masking (i.e., when a sound interferes with or masks the ability of an animal to detect a signal of interest that is above the absolute hearing threshold) may occur; the masking zone may be highly variable in size. We also describe more severe effects (i.e., certain non-auditory physical or physiological effects). Potential effects from impulsive sound sources can range in severity from effects such as behavioral disturbance or tactile perception to physical discomfort, slight injury of the internal organs and the auditory system, or mortality (Yelverton et al., 1973). Non-auditory physiological effects or injuries that theoretically might occur in marine mammals exposed to high level underwater sound or as a secondary effect of extreme behavioral reactions (e.g., change in dive profile as a result of an avoidance reaction) caused by exposure to sound include neurological effects, bubble formation, resonance effects, and other types of organ or tissue damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 2007; Tal et al., 2015). Acoustic Sources Direct Physiological Effects Based on the literature, there are two basic ways that non- impulsive sources might directly result in direct physiological effects. Noise-induced loss of hearing sensitivity (more commonly- called ``threshold shift'' (TS)) is the better-understood of these two effects, and the only one that is actually expected to occur. The second effect, acoustically mediated bubble growth and other pressure- related physiological impacts are addressed briefly below, but are not expected to result from the Navy's activities. Separately, an animal's behavioral reaction to an acoustic exposure might lead to physiological effects that might ultimately lead to injury or death, which is discussed later in the Stranding Section. Threshold Shift (Noise-Induced Loss of Hearing) When animals exhibit reduced hearing sensitivity within their auditory range (i.e., sounds must be louder for an animal to detect them) following exposure to a sufficiently intense sound or a less intense sound for a sufficient duration, it is referred to as a noise- induced TS. An animal can experience a TTS and/or PTS. TTS can last from minutes or hours to days (i.e., there is recovery back to baseline/pre-exposure levels), can occur within a specific frequency range (i.e., an animal might only have a temporary loss of hearing sensitivity within a limited frequency band of its auditory range), and can be [[Page 29914]] of varying amounts (for example, an animal's hearing sensitivity might be reduced by only 6 dB or reduced by 30 dB). Repeated sound exposure that leads to TTS could cause PTS. In severe cases of PTS, there can be total or partial deafness, while in most cases the animal has an impaired ability to hear sounds in specific frequency ranges (Kryter, 1985). When PTS occurs, there is physical damage to the sound receptors in the ear (i.e., tissue damage), whereas TTS represents primarily tissue fatigue and is reversible (Southall et al., 2007). PTS is permanent (i.e., there is incomplete recovery back to baseline/pre- exposure levels), but also can occur in a specific frequency range and amount as mentioned above for TTS. In addition, other investigators have suggested that TTS is within the normal bounds of physiological variability and tolerance and does not represent physical injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to constitute auditory injury. The following physiological mechanisms are thought to play a role in inducing auditory TS: Effects to sensory hair cells in the inner ear that reduce their sensitivity; modification of the chemical environment within the sensory cells; residual muscular activity in the middle ear; displacement of certain inner ear membranes; increased blood flow; and post-stimulatory reduction in both efferent and sensory neural output (Southall et al., 2007). The amplitude, duration, frequency, temporal pattern, and energy distribution of sound exposure all can affect the amount of associated TS and the frequency range in which it occurs. Generally, the amount of TS, and the time needed to recover from the effect, increase as amplitude and duration of sound exposure increases. Human non-impulsive noise exposure guidelines are based on the assumption that exposures of equal energy (the same SEL) produce equal amounts of hearing impairment regardless of how the sound energy is distributed in time (NIOSH, 1998). Previous marine mammal TTS studies have also generally supported this equal energy relationship (Southall et al., 2007). However, some more recent studies concluded that for all noise exposure situations the equal energy relationship may not be the best indicator to predict TTS onset levels (Mooney et al., 2009a and 2009b; Kastak et al., 2007). These studies highlight the inherent complexity of predicting TTS onset in marine mammals, as well as the importance of considering exposure duration when assessing potential impacts. Generally, with sound exposures of equal energy, those that were quieter (lower SPL) with longer duration were found to induce TTS onset at lower levels than those of louder (higher SPL) and shorter duration. Less TS will occur from intermittent sounds than from a continuous exposure with the same energy (some recovery can occur between intermittent exposures) (Kryter et al., 1966; Ward, 1997; Mooney et al., 2009a, 2009b; Finneran et al., 2010). For example, one short but loud (higher SPL) sound exposure may induce the same impairment as one longer but softer (lower SPL) sound, which in turn may cause more impairment than a series of several intermittent softer sounds with the same total energy (Ward, 1997). Additionally, though TTS is temporary, very prolonged or repeated exposure to sound strong enough to elicit TTS, or shorter-term exposure to sound levels well above the TTS threshold can cause PTS, at least in terrestrial mammals (Kryter, 1985; Lonsbury-Martin et al., 1987). PTS is considered auditory injury (Southall et al., 2007). Irreparable damage to the inner or outer cochlear hair cells may cause PTS; however, other mechanisms are also involved, such as exceeding the elastic limits of certain tissues and membranes in the middle and inner ears and resultant changes in the chemical composition of the inner ear fluids (Southall et al., 2007). Although the published body of scientific literature contains numerous theoretical studies and discussion papers on hearing impairments that can occur with exposure to a loud sound, only a few studies provide empirical information on the levels at which noise- induced loss in hearing sensitivity occurs in nonhuman animals. The NMFS 2016 Acoustic Technical Guidance, which was used in the assessment of effects for this action, compiled, interpreted, and synthesized the best available scientific information for noise-induced hearing effects for marine mammals to derive updated thresholds for assessing the impacts of noise on marine mammal hearing, as noted above. For cetaceans, published data on the onset of TTS are limited to the captive bottlenose dolphin, beluga, harbor porpoise, and Yangtze finless porpoise (summarized in Finneran, 2015). TTS studies involving exposure to other Navy activities (e.g., SURTASS LFA) or other low- frequency sonar (below 1 kHz) have never been conducted due to logistical difficulties of conducting experiments with low frequency sound sources. However, there are TTS measurements for exposures to other LF sources, such as seismic air guns. Finneran et al. (2015) suggest that the potential for air guns to cause hearing loss in dolphins is lower than previously predicted, perhaps as a result of the low-frequency content of air gun impulses compared to the high- frequency hearing ability of dolphins. Finneran et al. (2015) measured hearing thresholds in three captive bottlenose dolphins before and after exposure to ten pulses produced by a seismic air gun in order to study TTS induced after exposure to multiple pulses. Exposures began at relatively low levels and gradually increased over a period of several months, with the highest exposures at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 193-195 dB. No substantial TTS was observed. In addition, behavioral reactions were observed that indicated that animals can learn behaviors that effectively mitigate noise exposures (although exposure patterns must be learned, which is less likely in wild animals than for the captive animals considered in the study). The authors note that the failure to induce more significant auditory effects was likely due to the intermittent nature of exposure, the relatively low peak pressure produced by the acoustic source, and the low-frequency energy in air gun pulses as compared with the frequency range of best sensitivity for dolphins and other mid- frequency cetaceans. For pinnipeds in water, measurements of TTS are limited to harbor seals, elephant seals, and California sea lions (summarized in Finneran, 2015). Marine mammal hearing plays a critical role in communication with conspecifics and in interpretation of environmental cues for purposes such as predator avoidance and prey capture. Depending on the degree (elevation of threshold in dB), duration (i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious similar to those discussed in auditory masking, below. For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during a time when communication is critical for successful mother/calf interactions could have more serious impacts if it [[Page 29915]] were in the same frequency band as the necessary vocalizations and of a severity that impeded communication. The fact that animals exposed to high levels of sound that would be expected to result in this physiological response would also be expected to have behavioral responses of a comparatively more severe or sustained nature is potentially more significant than simple existence of a TTS. However, it is important to note that TTS could occur due to longer exposures to sound at lower levels so that a behavioral response may not be elicited. Depending on the degree and frequency range, the effects of PTS on an animal could also range in severity, although it is considered generally more serious than TTS because it is a permanent condition. Of note, reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall et al., 2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without some cost to the animal. Acoustically Mediated Bubble Growth and Other Pressure-Related Injury One theoretical cause of injury to marine mammals is rectified diffusion (Crum and Mao, 1996), the process of increasing the size of a bubble by exposing it to a sound field. This process could be facilitated if the environment in which the ensonified bubbles exist is supersaturated with gas. Repetitive diving by marine mammals can cause the blood and some tissues to accumulate gas to a greater degree than is supported by the surrounding environmental pressure (Ridgway and Howard, 1979). The deeper and longer dives of some marine mammals (for example, beaked whales) are theoretically predicted to induce greater supersaturation (Houser et al., 2001b). If rectified diffusion were possible in marine mammals exposed to high-level sound, conditions of tissue supersaturation could theoretically speed the rate and increase the size of bubble growth. Subsequent effects due to tissue trauma and emboli would presumably mirror those observed in humans suffering from decompression sickness. It is unlikely that the short duration (in combination with the source levels) of sonar pings would be long enough to drive bubble growth to any substantial size, if such a phenomenon occurs. However, an alternative but related hypothesis has also been suggested: Stable bubbles could be destabilized by high-level sound exposures such that bubble growth then occurs through static diffusion of gas out of the tissues. In such a scenario the marine mammal would need to be in a gas-supersaturated state for a long enough period of time for bubbles to become of a problematic size. Recent research with ex vivo supersaturated bovine tissues suggested that, for a 37 kHz signal, a sound exposure of approximately 215 dB referenced to (re) 1 [mu]Pa would be required before microbubbles became destabilized and grew (Crum et al., 2005). Assuming spherical spreading loss and a nominal sonar source level of 235 dB re 1 [mu]Pa at 1 m, a whale would need to be within 10 m (33 ft) of the sonar dome to be exposed to such sound levels. Furthermore, tissues in the study were supersaturated by exposing them to pressures of 400-700 kilopascals for periods of hours and then releasing them to ambient pressures. Assuming the equilibration of gases with the tissues occurred when the tissues were exposed to the high pressures, levels of supersaturation in the tissues could have been as high as 400-700 percent. These levels of tissue supersaturation are substantially higher than model predictions for marine mammals (Houser et al., 2001; Saunders et al., 2008). It is improbable that this mechanism is responsible for stranding events or traumas associated with beaked whale strandings because both the degree of supersaturation and exposure levels observed to cause microbubble destabilization are unlikely to occur, either alone or in concert. Yet another hypothesis (decompression sickness) has speculated that rapid ascent to the surface following exposure to a startling sound might produce tissue gas saturation sufficient for the evolution of nitrogen bubbles (Jepson et al., 2003; Fernandez et al., 2005; Fern[aacute]ndez et al., 2012). In this scenario, the rate of ascent would need to be sufficiently rapid to compromise behavioral or physiological protections against nitrogen bubble formation. Alternatively, Tyack et al. (2006) studied the deep diving behavior of beaked whales and concluded that: ``Using current models of breath-hold diving, we infer that their natural diving behavior is inconsistent with known problems of acute nitrogen supersaturation and embolism.'' Collectively, these hypotheses can be referred to as ``hypotheses of acoustically mediated bubble growth.'' Although theoretical predictions suggest the possibility for acoustically mediated bubble growth, there is considerable disagreement among scientists as to its likelihood (Piantadosi and Thalmann, 2004; Evans and Miller, 2003; Cox et al., 2006; Rommel et al., 2006). Crum and Mao (1996) hypothesized that received levels would have to exceed 190 dB in order for there to be the possibility of significant bubble growth due to supersaturation of gases in the blood (i.e., rectified diffusion). Work conducted by Crum et al. (2005) demonstrated the possibility of rectified diffusion for short duration signals, but at SELs and tissue saturation levels that are highly improbable to occur in diving marine mammals. To date, energy levels (ELs) predicted to cause in vivo bubble formation within diving cetaceans have not been evaluated (NOAA, 2002b). Jepson et al. (2003, 2005) and Fernandez et al. (2004, 2005, 2012) concluded that in vivo bubble formation, which may be exacerbated by deep, long-duration, repetitive dives may explain why beaked whales appear to be relatively vulnerable to MF/HF sonar exposures. It has also been argued that traumas from some beaked whale strandings are consistent with gas emboli and bubble-induced tissue separations (Jepson et al., 2003); however, there is no conclusive evidence of this (Rommel et al., 2006). In 2009, Hooker et al. tested two mathematical models to predict blood and tissue tension N2 (P N2 ) using field data from three beaked whale species: northern bottlenose whales, Cuvier's beaked whales, and Blainville's beaked whales. The researchers aimed to determine if physiology (body mass, diving lung volume, and dive response) or dive behavior (dive depth and duration, changes in ascent rate, and diel behavior) would lead to differences in PN2 levels and thereby decompression sickness risk between species. In their study, they compared results for previously published time depth recorder data (Hooker and Baird, 1999; Baird et al., 2006, 2008) from Cuvier's beaked whale, Blainville's beaked whale, and northern bottlenose whale. They reported that diving lung volume and extent of the dive response had a large effect on end-dive PN2 . Also, results showed that dive profiles had a larger influence on end-dive PN2 than body mass differences between species. Despite diel changes (i.e., variation that occurs regularly every day or most days) in dive behavior, PN2 levels showed no consistent trend. Model output suggested that all three species live with tissue PN2 levels that would cause a significant proportion of decompression sickness cases in terrestrial mammals. The authors concluded that the dive behavior of Cuvier's beaked whale was different from both Blainville's beaked whale, and northern bottlenose whale, [[Page 29916]] and resulted in higher predicted tissue and blood N2 levels (Hooker et al., 2009) and suggested that the prevalence of Cuvier's beaked whales stranding after naval sonar exercises could be explained by either a higher abundance of this species in the affected areas or by possible species differences in behavior and/or physiology related to MF active sonar (Hooker et al., 2009). Bernaldo de Quiros et al. (2012) showed that, among stranded whales, deep diving species of whales had higher abundances of gas bubbles compared to shallow diving species. Kvadsheim et al. (2012) estimated blood and tissue PN2 levels in species representing shallow, intermediate, and deep diving cetaceans following behavioral responses to sonar and their comparisons found that deep diving species had higher end-dive blood and tissue N2 levels, indicating a higher risk of developing gas bubble emboli compared with shallow diving species. Fahlmann et al. (2014) evaluated dive data recorded from sperm, killer, long-finned pilot, Blainville's beaked and Cuvier's beaked whales before and during exposure to low, as defined by the authors, (1-2 kHz) and mid (2-7 kHz) frequency active sonar in an attempt to determine if either differences in dive behavior or physiological responses to sonar are plausible risk factors for bubble formation. The authors suggested that CO2 may initiate bubble formation and growth, while elevated levels of N2 may be important for continued bubble growth. The authors also suggest that if CO2 plays an important role in bubble formation, a cetacean escaping a sound source may experience increased metabolic rate, CO2 production, and alteration in cardiac output, which could increase risk of gas bubble emboli. However, as discussed in Kvadsheim et al. (2012), the actual observed behavioral responses to sonar from the species in their study (sperm, killer, long-finned pilot, Blainville's beaked, and Cuvier's beaked whales) did not imply any significantly increased risk of decompression sickness due to high levels of N2. Therefore, further information is needed to understand the relationship between exposure to stimuli, behavioral response (discussed in more detail below), elevated N2 levels, and gas bubble emboli in marine mammals. The hypotheses for gas bubble formation related to beaked whale strandings is that beaked whales potentially have strong avoidance responses to MF active sonars because they sound similar to their main predator, the killer whale (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 2007; Baird et al., 2008; Hooker et al., 2009). Further investigation is needed to assess the potential validity of these hypotheses. To summarize, while there are several hypotheses, there is little data to support the potential for strong, anthropogenic underwater sounds to cause non-auditory physical effects in marine mammals. The available data do not support identification of a specific exposure level above which non-auditory effects can be expected (Southall et al., 2007) or any meaningful quantitative predictions of the numbers (if any) of marine mammals that might be affected in these ways. In addition, such effects, if they occur at all, would be expected to be limited to situations where marine mammals were exposed to high powered sounds at very close range over a prolonged period of time, which is not expected to occur based on the speed of the vessels operating sonar in combination with the speed and behavior of marine mammals in the vicinity of sonar. Acoustic Masking Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest (e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995; Erbe and Farmer, 2000; Tyack, 2000; Erbe et al., 2016). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural (e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest (e.g., signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities (e.g., sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions. Masking these acoustic signals can disturb the behavior of individual animals, groups of animals, or entire populations. In humans, significant masking of tonal signals occurs as a result of exposure to noise in a narrow band of similar frequencies. As the sound level increases, though, the detection of frequencies above those of the masking stimulus decreases also. This principle is expected to apply to marine mammals as well because of common biomechanical cochlear properties across taxa. Under certain circumstances, marine mammals experiencing significant masking could also be impaired from maximizing their performance fitness in survival and reproduction. Therefore, when the coincident (masking) sound is man-made, it may be considered harassment when disrupting or altering critical behaviors. It is important to distinguish TTS and PTS, which persist after the sound exposure from masking, which occurs during the sound exposure. Because masking (without resulting in TS) is not associated with abnormal physiological function, it is not considered a physiological effect, but rather a potential behavioral effect. The frequency range of the potentially masking sound is important in determining any potential behavioral impacts. For example, low- frequency signals may have less effect on high-frequency echolocation sounds produced by odontocetes but are more likely to affect detection of mysticete communication calls and other potentially important natural sounds such as those produced by surf and some prey species. The masking of communication signals by anthropogenic noise may be considered as a reduction in the communication space of animals (e.g., Clark et al., 2009; Matthews et al., 2016) and may result in energetic or other costs as animals change their vocalization behavior (e.g., Miller et al., 2000; Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt et al., 2009). Masking can be reduced in situations where the signal and noise come from different directions (Richardson et al., 1995), through amplitude modulation of the signal, or through other compensatory behaviors (Houser and Moore, 2014). Masking can be tested directly in captive species (e.g., Erbe, 2008), but in wild populations it must be either modeled or inferred from evidence of masking compensation. There are few studies addressing real-world masking sounds likely to be experienced by marine mammals in the wild (e.g., Branstetter et al., 2013). Masking affects both senders and receivers of acoustic signals and can potentially have long-term chronic effects on marine mammals at the population level as well as at the individual level. Low-frequency ambient sound levels have increased by as much as 20 dB (more than three times in terms of SPL) in the world's ocean [[Page 29917]] from pre-industrial periods, with most of the increase from distant commercial shipping (Hildebrand, 2009). All anthropogenic sound sources, but especially chronic and lower-frequency signals (e.g., from commercial vessel traffic), contribute to elevated ambient sound levels, thus intensifying masking. Richardson et al. (1995b) argued that the maximum radius of influence of an industrial noise (including broadband low-frequency sound transmission) on a marine mammal is the distance from the source to the point at which the noise can barely be heard. This range is determined by either the hearing sensitivity of the animal or the background noise level present. Industrial masking is most likely to affect some species' ability to detect communication calls and natural sounds (i.e., surf noise, prey noise, etc.; Richardson et al., 1995). The echolocation calls of toothed whales are subject to masking by high-frequency sound. Human data indicate low-frequency sound can mask high-frequency sounds (i.e., upward masking). Studies on captive odontocetes by Au et al. (1974, 1985, 1993) indicate that some species may use various processes to reduce masking effects (e.g., adjustments in echolocation call intensity or frequency as a function of background noise conditions). There is also evidence that the directional hearing abilities of odontocetes are useful in reducing masking at the high- frequencies these cetaceans use to echolocate, but not at the low-to- moderate frequencies they use to communicate (Zaitseva et al., 1980). A study by Nachtigall and Supin (2008) showed that false killer whales adjust their hearing to compensate for ambient sounds and the intensity of returning echolocation signals. Holt et al. (2009) measured killer whale call source levels and background noise levels in the one to 40 kHz band and reported that the whales increased their call source levels by one dB SPL for every one dB SPL increase in background noise level. Similarly, another study on St. Lawrence River belugas reported a similar rate of increase in vocalization activity in response to passing vessels (Scheifele et al., 2005). Parks et al. (2007) provided evidence of behavioral changes in the acoustic behaviors of the endangered North Atlantic right whale, and the South Atlantic southern right whale, and suggested that these were correlated to increased underwater noise levels. The study indicated that right whales might shift the frequency band of their calls to compensate for increased in-band background noise. The significance of their result is the indication of potential species-wide behavioral change in response to gradual, chronic increases in underwater ambient noise. Di Iorio and Clark (2010) showed that blue whale calling rates vary in association with seismic sparker survey activity, with whales calling more on days with survey than on days without surveys. They suggested that the whales called more during seismic survey periods as a way to compensate for the elevated noise conditions. Risch et al. (2012) documented reductions in humpback whale vocalizations in the Stellwagen Bank National Marine Sanctuary concurrent with transmissions of the Ocean Acoustic Waveguide Remote Sensing (OAWRS) low-frequency fish sensor system at distances of 200 km (124 mi) from the source. The recorded OAWRS produced a series of frequency modulated pulses and the signal received levels ranged from 88 to 110 dB re: 1 [mu]Pa (Risch, et al., 2012). The authors hypothesized that individuals did not leave the area but instead ceased singing and noted that the duration and frequency range of the OAWRS signals (a novel sound to the whales) were similar to those of natural humpback whale song components used during mating (Risch et al., 2012). Thus, the novelty of the sound to humpback whales in the Navy's Study Area (Navy's Atlantic Fleet Study Area) provided a compelling contextual probability for the observed effects (Risch et al., 2012). However, the authors did not state or imply that these changes had long-term effects on individual animals or populations (Risch et al., 2012). Redundancy and context can also facilitate detection of weak signals. These phenomena may help marine mammals detect weak sounds in the presence of natural or manmade noise. Most masking studies in marine mammals present the test signal and the masking noise from the same direction. The dominant background noise may be highly directional if it comes from a particular anthropogenic source such as a ship or industrial site. Directional hearing may significantly reduce the masking effects of these sounds by improving the effective signal-to- noise ratio. The functional hearing ranges of mysticetes, odontocetes, and pinnipeds underwater all overlap the frequencies of the sonar sources used in the Navy's low-frequency active sonar (LFAS)/mid-frequency active sonar (MFAS)/high-frequency active sonar (HFAS) training and testing exercises. Additionally, almost all species' vocal repertoires span across the frequencies of these sonar sources used by the Navy. The closer the characteristics of the masking signal to the signal of interest, the more likely masking is to occur. Although hull-mounted sonar accounts for a large portion of the area ensonified by Navy activities (because of the source strength and number of hours it is conducted), the pulse length and low duty cycle of the MFAS/HFAS signal makes it less likely that masking would occur as a result. Impaired Communication In addition to making it more difficult for animals to perceive acoustic cues in their environment, anthropogenic sound presents separate challenges for animals that are vocalizing. When they vocalize, animals are aware of environmental conditions that affect the ``active space'' of their vocalizations, which is the maximum area within which their vocalizations can be detected before it drops to the level of ambient noise (Brenowitz, 2004; Brumm et al., 2004; Lohr et al., 2003). Animals are also aware of environmental conditions that affect whether listeners can discriminate and recognize their vocalizations from other sounds, which is more important than simply detecting that a vocalization is occurring (Brenowitz, 1982; Brumm et al., 2004; Dooling, 2004, Marten and Marler, 1977; Patricelli et al., 2006). Most species that vocalize have evolved with an ability to make adjustments to their vocalizations to increase the signal-to-noise ratio, active space, and recognizability/distinguishability of their vocalizations in the face of temporary changes in background noise (Brumm et al., 2004; Patricelli et al., 2006). Vocalizing animals can make adjustments to vocalization characteristics such as the frequency structure, amplitude, temporal structure, and temporal delivery. Many animals will combine several of these strategies to compensate for high levels of background noise. Anthropogenic sounds that reduce the signal-to-noise ratio of animal vocalizations, increase the masked auditory thresholds of animals listening for such vocalizations, or reduce the active space of an animal's vocalizations impair communication between animals. Most animals that vocalize have evolved strategies to compensate for the effects of short-term or temporary increases in background or ambient noise on their songs or calls. Although the fitness consequences of these vocal adjustments are not directly known in all instances, like most other trade-offs animals must make, some of these [[Page 29918]] strategies probably come at a cost (Patricelli et al., 2006). Shifting songs and calls to higher frequencies may also impose energetic costs (Lambrechts, 1996). For example in birds, vocalizing more loudly in noisy environments may have energetic costs that decrease the net benefits of vocal adjustment and alter a bird's energy budget (Brumm, 2004; Wood and Yezerinac, 2006). Stress Response Classic stress responses begin when an animal's central nervous system perceives a potential threat to its homeostasis. That perception triggers stress responses regardless of whether a stimulus actually threatens the animal; the mere perception of a threat is sufficient to trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle, 1950). Once an animal's central nervous system perceives a threat, it mounts a biological response or defense that consists of a combination of the four general biological defense responses: behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses. According to Moberg (2000), in the case of many stressors, an animal's first and sometimes most economical (in terms of biotic costs) response is behavioral avoidance of the potential stressor or avoidance of continued exposure to a stressor. An animal's second line of defense to stressors involves the sympathetic part of the autonomic nervous system and the classical ``fight or flight'' response which includes the cardiovascular system, the gastrointestinal system, the exocrine glands, and the adrenal medulla to produce changes in heart rate, blood pressure, and gastrointestinal activity that humans commonly associate with ``stress.'' These responses have a relatively short duration and may or may not have significant long-term effect on an animal's welfare. An animal's third line of defense to stressors involves its neuroendocrine systems or sympathetic nervous systems; the system that has received the most study has been the hypothalmus-pituitary-adrenal system (also known as the HPA axis in mammals or the hypothalamus- pituitary-interrenal axis in fish and some reptiles). Unlike stress responses associated with the autonomic nervous system, virtually all neuro-endocrine functions that are affected by stress--including immune competence, reproduction, metabolism, and behavior--are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction (Moberg, 1987; Rivier and Rivest, 1991), altered metabolism (Elasser et al., 2000), reduced immune competence (Blecha, 2000), and behavioral disturbance (Moberg, 1987; Blecha, 2000). Increases in the circulation of glucocorticosteroids (cortisol, corticosterone, and aldosterone in marine mammals; see Romano et al., 2004) have been equated with stress for many years. The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and distress is the biotic cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose a risk to the animal's welfare. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other biotic function, which impairs those functions that experience the diversion. For example, when a stress response diverts energy away from growth in young animals, those animals may experience stunted growth. When a stress response diverts energy from a fetus, an animal's reproductive success and its fitness will suffer. In these cases, the animals will have entered a pre-pathological or pathological state which is called ``distress'' (Seyle, 1950) or ``allostatic loading'' (McEwen and Wingfield, 2003). This pathological state will last until the animal replenishes its biotic reserves sufficient to restore normal function. Note that these examples involved a long-term (days or weeks) stress response exposure to stimuli. Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses have also been documented fairly well through controlled experiments in terrestrial vertebrates; because this physiology exists in every vertebrate that has been studied, it is not surprising that stress responses and their costs have been documented in both laboratory and free-living animals (for examples see, Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005; Reneerkens et al., 2002; Thompson and Hamer, 2000). Information has also been collected on the physiological responses of marine mammals to exposure to anthropogenic sounds (Fair and Becker, 2000; Romano et al., 2002; Wright et al., 2008). Various efforts have been undertaken to investigate the impact from vessels (both whale- watching and general vessel traffic noise), and demonstrated impacts do occur (Bain, 2002; Erbe, 2002; Noren et al., 2009; Williams et al., 2006, 2009, 2014a, 2014b; Read et al., 2014; Rolland et al., 2012; Pirotta et al., 2015). This body of research for the most part has investigated impacts associated with the presence of chronic stressors, which differ significantly from the proposed Navy training and testing activities in the HSTT Study Area. For example, in an analysis of energy costs to killer whales, Williams et al. (2009) suggested that whale-watching in Canada's Johnstone Strait resulted in lost feeding opportunities due to vessel disturbance, which could carry higher costs than other measures of behavioral change might suggest. Ayres et al. (2012) recently reported on research in the Salish Sea (Washington state) involving the measurement of southern resident killer whale fecal hormones to assess two potential threats to the species recovery: Lack of prey (salmon) and impacts to behavior from vessel traffic. Ayres et al. (2012) suggested that the lack of prey overshadowed any population-level physiological impacts on southern resident killer whales from vessel traffic. Rolland et al. (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. In a conceptual model developed by the Population Consequences of Acoustic Disturbance (PCAD) working group, serum hormones were identified as possible indicators of behavioral effects that are translated into altered rates of reproduction and mortality (NRC, 2005). The Office of Naval Research hosted a workshop (Effects of Stress on Marine Mammals Exposed to Sound) in 2009 that focused on this very topic (ONR, 2009). Ultimately, the PCAD working group issued a report (Cochrem, 2014) that summarized information compiled from 239 papers or book chapters relating to stress in marine mammals and concluded that stress responses can last from minutes to hours and, while we typically focus on adverse stress responses, stress response is part of a natural process to help animals adjust to changes in their environment and can also be either neutral or beneficial. Despite the lack of robust information on stress responses for marine mammals exposed to anthropogenic sounds, studies of other marine animals and terrestrial animals would also lead us to expect some marine mammals to experience physiological stress responses and, perhaps, physiological responses that would be classified as [[Page 29919]] ``distress'' upon exposure to high frequency, mid-frequency, and low- frequency sounds. For example, Jansen (1998) reported on the relationship between acoustic exposures and physiological responses that are indicative of stress responses in humans (e.g., elevated respiration and increased heart rates). Jones (1998) reported on reductions in human performance when faced with acute, repetitive exposures to acoustic disturbance. Trimper et al. (1998) reported on the physiological stress responses of osprey to low-level aircraft noise while Krausman et al. (2004) reported on the auditory and physiological stress responses of endangered Sonoran pronghorn to military overflights. Smith et al. (2004a, 2004b) identified noise- induced physiological transient stress responses in hearing-specialist fish (i.e., goldfish) that accompanied short- and long-term hearing losses. Welch and Welch (1970) reported physiological and behavioral stress responses that accompanied damage to the inner ears of fish and several mammals. Behavioral Response/Disturbance Behavioral responses to sound are highly variable and context- specific. Many different variables can influence an animal's perception of and response to (nature and magnitude) an acoustic event. An animal's prior experience with a sound or sound source affects whether it is less likely (habituation) or more likely (sensitization) to respond to certain sounds in the future (animals can also be innately pre-disposed to respond to certain sounds in certain ways) (Southall et al., 2007). Related to the sound itself, the perceived nearness of the sound, bearing of the sound (approaching vs. retreating), similarity of a sound to biologically relevant sounds in the animal's environment (i.e., calls of predators, prey, or conspecifics), and familiarity of the sound may affect the way an animal responds to the sound (Southall et al., 2007, DeRuiter et al., 2013). Individuals (of different age, gender, reproductive status, etc.) among most populations will have variable hearing capabilities, and differing behavioral sensitivities to sounds that will be affected by prior conditioning, experience, and current activities of those individuals. Often, specific acoustic features of the sound and contextual variables (i.e., proximity, duration, or recurrence of the sound or the current behavior that the marine mammal is engaged in or its prior experience), as well as entirely separate factors such as the physical presence of a nearby vessel, may be more relevant to the animal's response than the received level alone. For example, Goldbogen et al. (2013) demonstrated that individual behavioral state was critically important in determining response of blue whales to sonar, noting that some individuals engaged in deep (>50 m) feeding behavior had greater dive responses than those in shallow feeding or non-feeding conditions. Some blue whales in the Goldbogen et al. (2013) study that were engaged in shallow feeding behavior demonstrated no clear changes in diving or movement even when RLs were high (~160 dB re 1[micro]Pa) for exposures to 3-4 kHz sonar signals, while others showed a clear response at exposures at lower RLs of sonar and pseudorandom noise. Studies by DeRuiter et al. (2012) indicate that variability of responses to acoustic stimuli depends not only on the species receiving the sound and the sound source, but also on the social, behavioral, or environmental contexts of exposure. Another study by DeRuiter et al. (2013) examined behavioral responses of Cuvier's beaked whales to MF sonar and found that whales responded strongly at low received levels (RL of 89-127 dB re 1[micro]Pa) by ceasing normal fluking and echolocation, swimming rapidly away, and extending both dive duration and subsequent non-foraging intervals when the sound source was 3.4-9.5 km away. Importantly, this study also showed that whales exposed to a similar range of RLs (78-106 dB re 1[micro]Pa) from distant sonar exercises (118 km away) did not elicit such responses, suggesting that context may moderate reactions. Ellison et al. (2012) outlined an approach to assessing the effects of sound on marine mammals that incorporates contextual-based factors. The authors recommend considering not just the received level of sound, but also the activity the animal is engaged in at the time the sound is received, the nature and novelty of the sound (i.e., is this a new sound from the animal's perspective), and the distance between the sound source and the animal. They submit that this ``exposure context,'' as described, greatly influences the type of behavioral response exhibited by the animal. This sort of contextual information is challenging to predict with accuracy for ongoing activities that occur over large spatial and temporal expanses. However, distance is one contextual factor for which data exist to quantitatively inform a take estimate, and the new method for predicting Level B harassment proposed in this notice does consider distance to the source. Other factors are often considered qualitatively in the analysis of the likely consequences of sound exposure, where supporting information is available. Friedlaender et al. (2016) provided the first integration of direct measures of prey distribution and density variables incorporated into across-individual analyses of behavior responses of blue whales to sonar, and demonstrated a five-fold increase in the ability to quantify variability in blue whale diving behavior. These results illustrate that responses evaluated without such measurements for foraging animals may be misleading, which again illustrates the context-dependent nature of the probability of response. Exposure of marine mammals to sound sources can result in, but is not limited to, no response or any of the following observable response: Increased alertness; orientation or attraction to a sound source; vocal modifications; cessation of feeding; cessation of social interaction; alteration of movement or diving behavior; habitat abandonment (temporary or permanent); and, in severe cases, panic, flight, stampede, or stranding, potentially resulting in death (Southall et al., 2007). A review of marine mammal responses to anthropogenic sound was first conducted by Richardson (1995). More recent reviews (Nowacek et al., 2007; DeRuiter et al., 2012 and 2013; Ellison et al., 2012) address studies conducted since 1995 and focused on observations where the received sound level of the exposed marine mammal(s) was known or could be estimated. Southall et al. (2016) states that results demonstrate that some individuals of different species display clear yet varied responses, some of which have negative implications, while others appear to tolerate high levels, and that responses may not be fully predicable with simple acoustic exposure metrics (e.g., received sound level). Rather, the authors state that differences among species and individuals along with contextual aspects of exposure (e.g., behavioral state) appear to affect response probability. The following sub-sections provide examples of behavioral responses that provide an idea of the variability in behavioral responses that would be expected given the differential sensitivities of marine mammal species to sound and the wide range of potential acoustic sources to which a marine mammal may be exposed. Predictions about of the types of behavioral responses that could occur for a given sound exposure should be determined from the literature that is available for each species, or extrapolated from closely related species when no information exists, along with contextual factors. [[Page 29920]] Flight Response A flight response is a dramatic change in normal movement to a directed and rapid movement away from the perceived location of a sound source. Relatively little information on flight responses of marine mammals to anthropogenic signals exist, although observations of flight responses to the presence of predators have occurred (Connor and Heithaus, 1996). Flight responses have been speculated as being a component of marine mammal strandings associated with sonar activities (Evans and England, 2001). If marine mammals respond to Navy vessels that are transmitting active sonar in the same way that they might respond to a predator, their probability of flight responses should increase when they perceive that Navy vessels are approaching them directly, because a direct approach may convey detection and intent to capture (Burger and Gochfeld, 1981, 1990; Cooper, 1997, 1998). There are limited data on flight response for marine mammals; however, there are examples of this response in terrestrial species. For instance, the probability of flight responses in Dall's sheep Ovis dalli dalli (Frid, 2001), hauled-out ringed seals Phoca hispida (Born et al., 1999), Pacific brant (Branta bernicl nigricans), and Canada geese (B. canadensis) increased as a helicopter or fixed-wing aircraft more directly approached groups of these animals (Ward et al., 1999). Bald eagles (Haliaeetus leucocephalus) perched on trees alongside a river were also more likely to flee from a paddle raft when their perches were closer to the river or were closer to the ground (Steidl and Anthony, 1996). Response to Predator Evidence suggests that at least some marine mammals have the ability to acoustically identify potential predators. For example, harbor seals that reside in the coastal waters off British Columbia are frequently targeted by certain groups of killer whales, but not others. The seals discriminate between the calls of threatening and non- threatening killer whales (Deecke et al., 2002), a capability that should increase survivorship while reducing the energy required for attending to and responding to all killer whale calls. The occurrence of masking or hearing impairment provides a means by which marine mammals may be prevented from responding to the acoustic cues produced by their predators. Whether or not this is a possibility depends on the duration of the masking/hearing impairment and the likelihood of encountering a predator during the time that predator cues are impeded. Alteration of Diving or Movement Changes in dive behavior can vary widely. They may consist of increased or decreased dive times and surface intervals as well as changes in the rates of ascent and descent during a dive. Variations in dive behavior may reflect interruptions in biologically significant activities (e.g., foraging) or they may be of little biological significance. Variations in dive behavior may also expose an animal to potentially harmful conditions (e.g., increasing the chance of ship- strike) or may serve as an avoidance response that enhances survivorship. The impact of a variation in diving resulting from an acoustic exposure depends on what the animal is doing at the time of the exposure and the type and magnitude of the response. Nowacek et al. (2004) reported disruptions of dive behaviors in foraging North Atlantic right whales when exposed to an alerting stimulus, an action, they noted, that could lead to an increased likelihood of ship strike. However, the whales did not respond to playbacks of either right whale social sounds or vessel noise, highlighting the importance of the sound characteristics in producing a behavioral reaction. Conversely, Indo-Pacific humpback dolphins have been observed to dive for longer periods of time in areas where vessels were present and/or approaching (Ng and Leung, 2003). In both of these studies, the influence of the sound exposure cannot be decoupled from the physical presence of a surface vessel, thus complicating interpretations of the relative contribution of each stimulus to the response. Indeed, the presence of surface vessels, their approach, and speed of approach, seemed to be significant factors in the response of the Indo-Pacific humpback dolphins (Ng and Leung, 2003). Low frequency signals of the Acoustic Thermometry of Ocean Climate (ATOC) sound source were not found to affect dive times of humpback whales in Hawaiian waters (Frankel and Clark, 2000) or to overtly affect elephant seal dives (Costa et al., 2003). They did, however, produce subtle effects that varied in direction and degree among the individual seals, illustrating the equivocal nature of behavioral effects and consequent difficulty in defining and predicting them. Lastly, as noted previously, DeRuiter et al. (2013) noted that distance from a sound source may moderate marine mammal reactions in their study of Cuvier's beaked whales showing the whales swimming rapidly and silently away when a sonar signal was 3.4-9.5 km away while showing no such reaction to the same signal when the signal was 118 km away even though the RLs were similar. Foraging Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators (e.g., bubble nets or sediment plumes), or changes in dive behavior. Noise from seismic surveys was not found to impact the feeding behavior in western grey whales off the coast of Russia (Yazvenko et al., 2007). Visual tracking, passive acoustic monitoring, and movement recording tags were used to quantify sperm whale behavior prior to, during, and following exposure to air gun arrays at received levels in the range 140-160 dB at distances of 7-13 km, following a phase-in of sound intensity and full array exposures at 1-13 km (Madsen et al., 2006a; Miller et al., 2009). Sperm whales did not exhibit horizontal avoidance behavior at the surface. However, foraging behavior may have been affected. The sperm whales exhibited 19 percent less vocal (buzz) rate during full exposure relative to post exposure, and the whale that was approached most closely had an extended resting period and did not resume foraging until the air guns had ceased firing. The remaining whales continued to execute foraging dives throughout exposure; however, swimming movements during foraging dives were six percent lower during exposure than control periods (Miller et al., 2009). These data raise concerns that air gun surveys may impact foraging behavior in sperm whales, although more data are required to understand whether the differences were due to exposure or natural variation in sperm whale behavior (Miller et al., 2009). Balaenopterid whales exposed to moderate low-frequency signals similar to the ATOC sound source demonstrated no variation in foraging activity (Croll et al., 2001), whereas five out of six North Atlantic right whales exposed to an acoustic alarm interrupted their foraging dives (Nowacek et al., 2004). Although the received SPLs were similar in the latter two studies, the frequency, duration, and temporal pattern of signal presentation were different. These factors, as well as differences in species sensitivity, are likely contributing factors to the differential response. Blue whales exposed to mid-frequency sonar in the Southern California Bight were [[Page 29921]] less likely to produce low frequency calls usually associated with feeding behavior (Melc[oacute]n et al., 2012). However, Melc[oacute]n et al. (2012) were unable to determine if suppression of low frequency calls reflected a change in their feeding performance or abandonment of foraging behavior and indicated that implications of the documented responses are unknown. Further, it is not known whether the lower rates of calling actually indicated a reduction in feeding behavior or social contact since the study used data from remotely deployed, passive acoustic monitoring buoys. In contrast, blue whales increased their likelihood of calling when ship noise was present, and decreased their likelihood of calling in the presence of explosive noise, although this result was not statistically significant (Melc[oacute]n et al., 2012). Additionally, the likelihood of an animal calling decreased with the increased received level of mid-frequency sonar, beginning at a SPL of approximately 110-120 dB re 1 [micro]Pa (Melc[oacute]n et al., 2012). Results from the 2010-2011 field season of an ongoing behavioral response study in Southern California waters indicated that, in some cases and at low received levels, tagged blue whales responded to mid- frequency sonar but that those responses were mild and there was a quick return to their baseline activity (Southall et al., 2011; Southall et al., 2012b). Information on or estimates of the energetic requirements of the individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal will help better inform a determination of whether foraging disruptions incur fitness consequences. Goldbogen et al. (2013) monitored behavioral responses of tagged blue whales located in feeding areas when exposed to simulated MFA sonar. Responses varied depending on behavioral context, with some deep feeding whales being more significantly affected (i.e., generalized avoidance; cessation of feeding; increased swimming speeds; or directed travel away from the source) compared to surface feeding individuals that typically showed no change in behavior. The authors indicate that disruption of feeding and displacement could impact individual fitness and health. However, for this to be true, we would have to assume that an individual whale could not compensate for this lost feeding opportunity by either immediately feeding at another location, by feeding shortly after cessation of acoustic exposure, or by feeding at a later time. There is no indication this is the case, particularly since unconsumed prey would likely still be available in the environment in most cases following the cessation of acoustic exposure. Breathing Variations in respiration naturally vary with different behaviors and variations in respiration rate as a function of acoustic exposure can be expected to co-occur with other behavioral reactions, such as a flight response or an alteration in diving. However, respiration rates in and of themselves may be representative of annoyance or an acute stress response. Mean exhalation rates of gray whales at rest and while diving were found to be unaffected by seismic surveys conducted adjacent to the whale feeding grounds (Gailey et al., 2007). Studies with captive harbor porpoises showed increased respiration rates upon introduction of acoustic alarms (Kastelein et al., 2001; Kastelein et al., 2006a) and emissions for underwater data transmission (Kastelein et al., 2005). However, exposure of the same acoustic alarm to a striped dolphin under the same conditions did not elicit a response (Kastelein et al., 2006a), again highlighting the importance in understanding species differences in the tolerance of underwater noise when determining the potential for impacts resulting from anthropogenic sound exposure. Social Relationships Social interactions between mammals can be affected by noise via the disruption of communication signals or by the displacement of individuals. Disruption of social relationships therefore depends on the disruption of other behaviors (e.g., caused avoidance, masking, etc.). Sperm whales responded to military sonar, apparently from a submarine, by dispersing from social aggregations, moving away from the sound source, remaining relatively silent, and becoming difficult to approach (Watkins et al., 1985). In contrast, sperm whales in the Mediterranean that were exposed to submarine sonar continued calling (J. Gordon pers. comm. cited in Richardson et al., 1995). Long-finned pilot whales exposed to three types of disturbance--playbacks of killer whale sounds, naval sonar exposure, and tagging all resulted in increased group sizes (Visser et al., 2016). In response to sonar, pilot whales also spent more time at the surface with other members of the group (Visser et al., 2016). However, social disruptions must be considered in context of the relationships that are affected. While some disruptions may not have deleterious effects, others, such as long-term or repeated disruptions of mother/calf pairs or interruption of mating behaviors, have the potential to affect the growth and survival or reproductive effort/success of individuals. Vocalizations (Also See Masking Section) Vocal changes in response to anthropogenic noise can occur across the repertoire of sound production modes used by marine mammals, such as whistling, echolocation click production, calling, and singing. Changes may result in response to a need to compete with an increase in background noise or may reflect an increased vigilance or startle response. For example, in the presence of low-frequency active sonar, humpback whales have been observed to increase the length of their ``songs'' (Miller et al., 2000; Fristrup et al., 2003), possibly due to the overlap in frequencies between the whale song and the low-frequency active sonar. A similar compensatory effect for the presence of low- frequency vessel noise has been suggested for right whales; right whales have been observed to shift the frequency content of their calls upward while reducing the rate of calling in areas of increased anthropogenic noise (Parks et al., 2007; Roland et al., 2012). Killer whales off the northwestern coast of the United States have been observed to increase the duration of primary calls once a threshold in observing vessel density (e.g., whale watching) was reached, which has been suggested as a response to increased masking noise produced by the vessels (Foote et al., 2004; NOAA, 2014b). In contrast, both sperm and pilot whales potentially ceased sound production during the Heard Island feasibility test (Bowles et al., 1994), although it cannot be absolutely determined whether the inability to acoustically detect the animals was due to the cessation of sound production or the displacement of animals from the area. Cerchio et al. (2014) used passive acoustic monitoring to document the presence of singing humpback whales off the coast of northern Angola and to opportunistically test for the effect of seismic survey activity on the number of singing whales. Two recording units were deployed between March and December 2008 in the offshore environment; numbers of singers were counted every hour. Generalized Additive Mixed Models were used to assess the effect of survey day (seasonality), hour (diel variation), moon phase, and received levels of [[Page 29922]] noise (measured from a single pulse during each ten-minute sampled period) on singer number. The number of singers significantly decreased with increasing received level of noise, suggesting that humpback whale communication was disrupted to some extent by the survey activity. Castellote et al. (2012) reported acoustic and behavioral changes by fin whales in response to shipping and air gun noise. Acoustic features of fin whale song notes recorded in the Mediterranean Sea and northeast Atlantic Ocean were compared for areas with different shipping noise levels and traffic intensities and during an air gun survey. During the first 72 hrs of the survey, a steady decrease in song received levels and bearings to singers indicated that whales moved away from the acoustic source and out of a Navy Study Area. This displacement persisted for a time period well beyond the 10-day duration of air gun activity, providing evidence that fin whales may avoid an area for an extended period in the presence of increased noise. The authors hypothesize tha fin whale acoustic communication is modified to compensate for increased background noise and that a sensitization process may play a role in the observed temporary displacement. Seismic pulses at average received levels of 131 dB re 1 micropascal squared per second ([micro]Pa2-s) caused blue whales to increase call production (Di Iorio and Clark, 2010). In contrast, McDonald et al. (1995) tracked a blue whale with seafloor seismometers and reported that it stopped vocalizing and changed its travel direction at a range of 10 km from the seismic vessel (estimated received level 143 dB re 1 [micro]Pa peak-to-peak). Blackwell et al. (2013) found that bowhead whale call rates dropped significantly at onset of air gun use at sites with a median distance of 41-45 km from the survey. Blackwell et al. (2015) expanded this analysis to show that whales actually increased calling rates as soon as air gun signals were detectable before ultimately decreasing calling rates at higher received levels (i.e., 10-minute cSEL of ~127 dB). Overall, these results suggest that bowhead whales may adjust their vocal output in an effort to compensate for noise before ceasing vocalization effort and ultimately deflecting from the acoustic source (Blackwell et al., 2013, 2015). Captive bottlenose dolphins sometimes vocalized after an exposure to impulse sound from a seismic water gun (Finneran et al., 2010a). These studies demonstrate that even low levels of noise received far from the noise source can induce behavioral responses. Avoidance Avoidance is the displacement of an individual from an area as a result of the presence of a sound. Richardson et al. (1995) noted that avoidance reactions are the most obvious manifestations of disturbance in marine mammals. Avoidance is qualitatively different from the flight response, but also differs in the magnitude of the response (i.e., directed movement, rate of travel, etc.). Oftentimes avoidance is temporary, and animals return to the area once the noise has ceased. However, longer term displacement is possible and can lead to changes in abundance or distribution patterns of the species in the affected region if they do not become acclimated to the presence of the sound (Blackwell et al., 2004; Bejder et al., 2006; Teilmann et al., 2006). Acute avoidance responses have been observed in captive porpoises and pinnipeds exposed to a number of different sound sources (Kastelein et al., 2001; Finneran et al., 2003; Kastelein et al., 2006a; Kastelein et al., 2006b). Short-term avoidance of seismic surveys, low frequency emissions, and acoustic deterrents have also been noted in wild populations of odontocetes (Bowles et al., 1994; Goold, 1996; 1998; Stone et al., 2000; Morton and Symonds, 2002) and to some extent in mysticetes (Gailey et al., 2007), while longer term or repetitive/ chronic displacement for some dolphin groups and for manatees has been suggested to be due to the presence of chronic vessel noise (Haviland- Howell et al., 2007; Miksis-Olds et al., 2007). Gray whales have been reported deflecting from customary migratory paths in order to avoid noise from air gun surveys (Malme et al., 1984). Humpback whales showed avoidance behavior in the presence of an active air gun array during observational studies and controlled exposure experiments in western Australia (McCauley et al., 2000a). In 1998, the Navy conducted a Low Frequency Sonar Scientific Research Program (LFS SRP) specifically to study behavioral responses of several species of marine mammals to exposure to LF sound, including one phase that focused on the behavior of gray whales to low frequency sound signals. The objective of this phase of the LFS SRP was to determine whether migrating gray whales respond more strongly to received levels, sound gradient, or distance from the source, and to compare whale avoidance responses to an LF source in the center of the migration corridor versus in the offshore portion of the migration corridor. A single source was used to broadcast LFA sonar sounds at received levels of 170-178 dB re 1[micro]Pa. The Navy reported that the whales showed some avoidance responses when the source was moored one mile (1.8 km) offshore, and located within in the migration path, but the whales returned to their migration path when they were a few kilometers beyond the source. When the source was moored two miles (3.7 km) offshore, responses were much less even when the source level was increased to achieve the same RLs in the middle of the migration corridor as whales received when the source was located within the migration corridor (Clark et al., 1999). In addition, the researchers noted that the offshore whales did not seem to avoid the louder offshore source. Also during the LFS SRP, researchers sighted numerous odontocete and pinniped species in the vicinity of the sound exposure tests with LFA sonar. The MF and HF hearing specialists present in California and Hawaii showed no immediately obvious responses or changes in sighting rates as a function of source conditions. Consequently, the researchers concluded that none of these species had any obvious behavioral reaction to LFA sonar signals at received levels similar to those that produced only minor short-term behavioral responses in the baleen whales (i.e., LF hearing specialists). Thus, for odontocetes, the chances of injury and/or significant behavioral responses to LFA sonar would be low given the MF/HF specialists' observed lack of response to LFA sounds during the LFS SRP and due to the MF/HF frequencies to which these animals are adapted to hear (Clark and Southall, 2009). Maybaum (1993) conducted sound playback experiments to assess the effects of MFAS on humpback whales in Hawaiian waters. Specifically, she exposed focal pods to sounds of a 3.3-kHz sonar pulse, a sonar frequency sweep from 3.1 to 3.6 kHz, and a control (blank) tape while monitoring behavior, movement, and underwater vocalizations. The two types of sonar signals differed in their effects on the humpback whales, but both resulted in avoidance behavior. The whales responded to the pulse by increasing their distance from the sound source and responded to the frequency sweep by increasing their swimming speeds and track linearity. In the Caribbean, sperm whales avoided exposure to mid-frequency submarine sonar pulses, in the range of 1000 Hz to 10,000 Hz (IWC, 2005). [[Page 29923]] Kvadsheim et al. (2007) conducted a controlled exposure experiment in which killer whales fitted with D-tags were exposed to mid-frequency active sonar (Source A: A 1.0 second upsweep 209 dB @1-2 kHz every 10 seconds for 10 minutes; Source B: With a 1.0 second upsweep 197 dB @6-7 kHz every 10 seconds for 10 minutes). When exposed to Source A, a tagged whale and the group it was traveling with did not appear to avoid the source. When exposed to Source B, the tagged whales along with other whales that had been carousel feeding, where killer whales cooperatively herd fish schools into a tight ball towards the surface and feed on the fish which have been stunned by tailslaps and subsurface feeding (Simila, 1997), ceased feeding during the approach of the sonar and moved rapidly away from the source. When exposed to Source B, Kvadsheim et al. (2007) reported that a tagged killer whale seemed to try to avoid further exposure to the sound field by the following behaviors: Immediately swimming away (horizontally) from the source of the sound; engaging in a series of erratic and frequently deep dives that seemed to take it below the sound field; or swimming away while engaged in a series of erratic and frequently deep dives. Although the sample sizes in this study are too small to support statistical analysis, the behavioral responses of the killer whales were consistent with the results of other studies. Southall et al. (2007) reviewed the available literature on marine mammal hearing and physiological and behavioral responses to human-made sound with the goal of proposing exposure criteria for certain effects. This peer-reviewed compilation of literature is very valuable, though Southall et al. (2007) note that not all data are equal, some have poor statistical power, insufficient controls, and/or limited information on received levels, background noise, and other potentially important contextual variables. Such data were reviewed and sometimes used for qualitative illustration, but no quantitative criteria were recommended for behavioral responses. All of the studies considered, however, contain an estimate of the received sound level when the animal exhibited the indicated response. In the Southall et al. (2007) publication, for the purposes of analyzing responses of marine mammals to anthropogenic sound and developing criteria, the authors differentiate between single pulse sounds, multiple pulse sounds, and non-pulse sounds. LFAS/MFAS/HFAS are considered non-pulse sounds. Southall et al. (2007) summarize the studies associated with low-frequency, mid-frequency, and high- frequency cetacean and pinniped responses to non-pulse sounds, based strictly on received level, in Appendix C of their article (included in this preamble by reference and summarized in the following paragraphs below). The studies that address responses of low-frequency cetaceans to non-pulse sounds include data gathered in the field and related to several types of sound sources (of varying similarity to MFAS/HFAS) including: Vessel noise, drilling and machinery playback, low-frequency M-sequences (sine wave with multiple phase reversals) playback, tactical low-frequency active sonar playback, drill ships, Acoustic Thermometry of Ocean Climate (ATOC) source, and non-pulse playbacks. These studies generally indicate no (or very limited) responses to received levels in the 90 to 120 dB re: 1 [micro]Pa range and an increasing likelihood of avoidance and other behavioral effects in the 120 to 160 dB re: 1 [micro]Pa range. As mentioned earlier, though, contextual variables play a very important role in the reported responses and the severity of effects are not linear when compared to received level. Also, few of the laboratory or field datasets had common conditions, behavioral contexts or sound sources, so it is not surprising that responses differ. The studies that address responses of mid-frequency cetaceans to non-pulse sounds include data gathered both in the field and the laboratory and related to several different sound sources (of varying similarity to MFAS/HFAS) including: Pingers, drilling playbacks, ship and ice-breaking noise, vessel noise, Acoustic Harassment Devices (AHDs), Acoustic Deterrent Devices (ADDs), MFAS, and non-pulse bands and tones. Southall et al. (2007) were unable to come to a clear conclusion regarding the results of these studies. In some cases, animals in the field showed significant responses to received levels between 90 and 120 dB re: 1 [micro]Pa, while in other cases these responses were not seen in the 120 to 150 dB re: 1 [micro]Pa range. The disparity in results was likely due to contextual variation and the differences between the results in the field and laboratory data (animals typically responded at lower levels in the field). The studies that address responses of high-frequency cetaceans to non-pulse sounds include data gathered both in the field and the laboratory and related to several different sound sources (of varying similarity to MFAS/HFAS) including: Pingers, AHDs, and various laboratory non-pulse sounds. All of these data were collected from harbor porpoises. Southall et al. (2007) concluded that the existing data indicate that harbor porpoises are likely sensitive to a wide range of anthropogenic sounds at low received levels (~90 to 120 dB re: 1 [micro]Pa), at least for initial exposures. All recorded exposures above 140 dB re: 1 [micro]Pa induced profound and sustained avoidance behavior in wild harbor porpoises (Southall et al., 2007). Rapid habituation was noted in some but not all studies. There are no data to indicate whether other high frequency cetaceans are as sensitive to anthropogenic sound as harbor porpoises. The studies that address the responses of pinnipeds in water to non-impulsive sounds include data gathered both in the field and the laboratory and related to several different sound sources including: AHDs, ATOC, various non-pulse sounds used in underwater data communication, underwater drilling, and construction noise. Few studies exist with enough information to include them in the analysis. The limited data suggested that exposures to non-pulse sounds between 90 and 140 dB re: 1 [micro]Pa generally do not result in strong behavioral responses in pinnipeds in water, but no data exist at higher received levels. In 2007, the first in a series of behavioral response studies (BRS) on deep diving odontocetes conducted by NMFS, Navy, and other scientists showed one Blainville's beaked whale responding to an MFAS playback. Tyack et al. (2011) indicates that the playback began when the tagged beaked whale was vocalizing at depth (at the deepest part of a typical feeding dive), following a previous control with no sound exposure. The whale appeared to stop clicking significantly earlier than usual, when exposed to MF signals in the 130-140 dB (rms) received level range. After a few more minutes of the playback, when the received level reached a maximum of 140-150 dB, the whale ascended on the slow side of normal ascent rates with a longer than normal ascent, at which point the exposure was terminated. The results are from a single experiment and a greater sample size is needed before robust and definitive conclusions can be drawn. Tyack et al. (2011) also indicates that Blainville's beaked whales appear to be sensitive to noise at levels well below expected TTS (~160 dB re1[micro]Pa). This sensitivity was manifested by an adaptive movement away from a sound source. This response was observed irrespective of whether the signal transmitted was within the band width of MFAS, which suggests that beaked whales may not [[Page 29924]] respond to the specific sound signatures. Instead, they may be sensitive to any pulsed sound from a point source in this frequency range of the MF active sonar transmission. The response to such stimuli appears to involve the beaked whale increasing the distance between it and the sound source. Overall the results from the 2007-2008 study conducted showed a change in diving behavior of the Blainville's beaked whale to playback of MFAS and predator sounds (Boyd et al., 2008; Southall et al., 2009; Tyack et al., 2011). Stimpert et al. (2014) tagged a Baird's beaked whale, which was subsequently exposed to simulated MFAS. Received levels of sonar on the tag increased to a maximum of 138 dB re 1[mu]Pa, which occurred during the first exposure dive. Some sonar received levels could not be measured due to flow noise and surface noise on the tag. Reaction to mid-frequency sounds included premature cessation of clicking and termination of a foraging dive, and a slower ascent rate to the surface. Results from a similar behavioral response study in southern California waters have been presented for the 2010-2011 field season (Southall et al., 2011; DeRuiter et al., 2013b). DeRuiter et al. (2013b) presented results from two Cuvier's beaked whales that were tagged and exposed to simulated MFAS during the 2010 and 2011 field seasons of the southern California behavioral response study. The 2011 whale was also incidentally exposed to MFAS from a distant naval exercise. Received levels from the MFAS signals from the controlled and incidental exposures were calculated as 84-144 and 78-106 dB re 1 [micro]Pa rms, respectively. Both whales showed responses to the controlled exposures, ranging from initial orientation changes to avoidance responses characterized by energetic fluking and swimming away from the source. However, the authors did not detect similar responses to incidental exposure to distant naval sonar exercises at comparable received levels, indicating that context of the exposures (e.g., source proximity, controlled source ramp-up) may have been a significant factor. Specifically, this result suggests that caution is needed when using marine mammal response data collected from smaller, nearer sound sources to predict at what received levels animals may respond to larger sound sources that are significantly farther away--as the distance of the source appears to be an important contextual variable and animals may be less responsive to sources at notably greater distances. Cuvier's beaked whale responses suggested particular sensitivity to sound exposure as consistent with results for Blainville's beaked whale. Similarly, beaked whales exposed to sonar during British training exercises stopped foraging (DSTL, 2007), and preliminary results of controlled playback of sonar may indicate feeding/foraging disruption of killer whales and sperm whales (Miller et al., 2011). In the 2007-2008 Bahamas study, playback sounds of a potential predator--a killer whale--resulted in a similar but more pronounced reaction, which included longer inter-dive intervals and a sustained straight-line departure of more than 20 km from the area (Boyd et al., 2008; Southall et al., 2009; Tyack et al., 2011). The authors noted, however, that the magnified reaction to the predator sounds could represent a cumulative effect of exposure to the two sound types since killer whale playback began approximately two hours after MF source playback. Pilot whales and killer whales off Norway also exhibited horizontal avoidance of a transducer with outputs in the mid-frequency range (signals in the 1-2 kHz and 6-7 kHz ranges) (Miller et al., 2011). Additionally, separation of a calf from its group during exposure to MFAS playback was observed on one occasion (Miller et al., 2011, 2012). Miller et al. (2012) noted that this single observed mother-calf separation was unusual for several reasons, including the fact that the experiment was conducted in an unusually narrow fjord roughly one km wide and that the sonar exposure was started unusually close to the pod including the calf. Both of these factors could have contributed to calf separation. In contrast, preliminary analyses suggest that none of the pilot whales or false killer whales in the Bahamas showed an avoidance response to controlled exposure playbacks (Southall et al., 2009). In the 2010 BRS study, researchers again used controlled exposure experiments (CEE) to carefully measure behavioral responses of individual animals to sound exposures of MF active sonar and pseudo- random noise. For each sound type, some exposures were conducted when animals were in a surface feeding (approximately 164 ft (50 m) or less) and/or socializing behavioral state and others while animals were in a deep feeding (greater than 164 ft (50 m)) and/or traveling mode. The researchers conducted the largest number of CEEs on blue whales (n=19) and of these, 11 CEEs involved exposure to the MF active sonar sound type. For the majority of CEE transmissions of either sound type, they noted few obvious behavioral responses detected either by the visual observers or on initial inspection of the tag data. The researchers observed that throughout the CEE transmissions, up to the highest received sound level (absolute RMS value approximately 160 dB re: 1[mu]Pa with signal-to-noise ratio values over 60 dB), two blue whales continued surface feeding behavior and remained at a range of around 3,820 ft (1,000 m) from the sound source (Southall et al., 2011). In contrast, another blue whale (later in the day and greater than 11.5 mi (18.5 km; 10 nmi) from the first CEE location) exposed to the same stimulus (MFA) while engaged in a deep feeding/travel state exhibited a different response. In that case, the blue whale responded almost immediately following the start of sound transmissions when received sounds were just above ambient background levels (Southall et al., 2011). The authors note that this kind of temporary avoidance behavior was not evident in any of the nine CEEs involving blue whales engaged in surface feeding or social behaviors, but was observed in three of the ten CEEs for blue whales in deep feeding/travel behavioral modes (one involving MFA sonar; two involving pseudo-random noise) (Southall et al., 2011). The results of this study, as well as the results of the DeRuiter et al. (2013) study of Cuvier's beaked whales discussed above, further illustrate the importance of behavioral context in understanding and predicting behavioral responses. Through analysis of the behavioral response studies, a preliminary overarching effect of greater sensitivity to all anthropogenic exposures was seen in beaked whales compared to the other odontocetes studied (Southall et al., 2009). Therefore, recent studies have focused specifically on beaked whale responses to active sonar transmissions or controlled exposure playback of simulated sonar on various military ranges (Defence Science and Technology Laboratory, 2007; Claridge and Durban, 2009; Moretti et al., 2009; McCarthy et al., 2011; Miller et al., 2012; Southall et al., 2011, 2012a, 2012b, 2013, 2014; Tyack et al., 2011). In the Bahamas, Blainville's beaked whales located on the instrumented range will move off-range during sonar use and return only after the sonar transmissions have stopped, sometimes taking several days to do so (Claridge and Durban 2009; Moretti et al., 2009; McCarthy et al., 2011; Tyack et al., 2011). Moretti et al. (2014) used recordings from seafloor-mounted [[Page 29925]] hydrophones at the Atlantic Undersea Test and Evaluation Center (AUTEC) to analyze the probability of Blainsville's beaked whale dives before, during, and after Navy sonar exercises. Southall et al. (2016) indicates that results from Tyack et al. (2011); Miller et al. (2015), Stimpert et al. (2014), and DeRuiter et al. (2013) beaked whale studies all demonstrate clear, strong, and pronounced but varied behavioral changes including sustained avoidance with associated energetic swimming and cessation of feeding behavior at quite low received levels (~100 to 135 dB re 1Pa) for exposures to simulated or active MF military sonars (1 to 8 kHz) with sound sources approximately 2 to 5 km away. Baleen whales have shown a variety of responses to impulse sound sources, including avoidance, reduced surface intervals, altered swimming behavior, and changes in vocalization rates (Richardson et al., 1995; Gordon et al., 2003; Southall, 2007). While most bowhead whales did not show active avoidance until within 8 km of seismic vessels (Richardson et al., 1995), some whales avoided vessels by more than 20 km at received levels as low as 120 dB re 1 [micro]Pa rms. Additionally, Malme et al. (1988) observed clear changes in diving and respiration patterns in bowheads at ranges up to 73 km from seismic vessels, with received levels as low as 125 dB re 1 [micro]Pa. Gray whales migrating along the U.S. west coast showed avoidance responses to seismic vessels by 10 percent of animals at 164 dB re 1 [micro]Pa, and by 90 percent of animals at 190 dB re 1 [micro]Pa, with similar results for whales in the Bering Sea (Malme, 1986; 1988). In contrast, noise from seismic surveys was not found to impact feeding behavior or exhalation rates while resting or diving in western gray whales off the coast of Russia (Yazvenko et al., 2007; Gailey et al., 2007). Humpback whales showed avoidance behavior at ranges of five to eight km from a seismic array during observational studies and controlled exposure experiments in western Australia (McCauley, 1998; Todd et al., 1996). Todd found no clear short-term behavioral responses by foraging humpbacks to explosions associated with construction operations in Newfoundland, but did see a trend of increased rates of net entanglement and a shift to a higher incidence of net entanglement closer to the noise source. Orientation A shift in an animal's resting state or an attentional change via an orienting response represent behaviors that would be considered mild disruptions if occurring alone. As previously mentioned, the responses may co-occur with other behaviors; for instance, an animal may initially orient toward a sound source, and then move away from it. Thus, any orienting response should be considered in context of other reactions that may occur. Continued Pre-Disturbance Behavior and Habituation Under some circumstances, some of the individual marine mammals that are exposed to active sonar transmissions will continue their normal behavioral activities. In other circumstances, individual animals will respond to sonar transmissions at lower received levels and move to avoid additional exposure or exposures at higher received levels (Richardson et al., 1995). It is difficult to distinguish between animals that continue their pre-disturbance behavior without stress responses, animals that continue their behavior but experience stress responses (that is, animals that cope with disturbance), and animals that habituate to disturbance (that is, they may have experienced low-level stress responses initially, but those responses abated over time). Watkins (1986) reviewed data on the behavioral reactions of fin, humpback, right and minke whales that were exposed to continuous, broadband low- frequency shipping and industrial noise in Cape Cod Bay. He concluded that underwater sound was the primary cause of behavioral reactions in these species of whales and that the whales responded behaviorally to acoustic stimuli within their respective hearing ranges. Watkins also noted that whales showed the strongest behavioral reactions to sounds in the 15 Hz to 28 kHz range, although negative reactions (avoidance, interruptions in vocalizations, etc.) were generally associated with sounds that were either unexpected, too loud, suddenly louder or different, or perceived as being associated with a potential threat (such as an approaching ship on a collision course). In particular, whales seemed to react negatively when they were within 100 m of the source or when received levels increased suddenly in excess of 12 dB relative to ambient sounds. At other times, the whales ignored the source of the signal and all four species habituated to these sounds. Nevertheless, Watkins concluded that whales ignored most sounds in the background of ambient noise, including sounds from distant human activities even though these sounds may have had considerable energies at frequencies well within the whales' range of hearing. Further, he noted that of the whales observed, fin whales were the most sensitive of the four species, followed by humpback whales; right whales were the least likely to be disturbed and generally did not react to low- amplitude engine noise. By the end of his period of study, Watkins (1986) concluded that fin and humpback whales have generally habituated to the continuous and broad-band noise of Cape Cod Bay while right whales did not appear to change their response. As mentioned above, animals that habituate to a particular disturbance may have experienced low-level stress responses initially, but those responses abated over time. In most cases, this likely means a lessened immediate potential effect from a disturbance. However, there is cause for concern where the habituation occurs in a potentially more harmful situation. For example, animals may become more vulnerable to vessel strikes once they habituate to vessel traffic (Swingle et al., 1993; Wiley et al., 1995). Aicken et al. (2005) monitored the behavioral responses of marine mammals to a new low-frequency active sonar system used by the British Navy (the United States Navy considers this to be a mid-frequency source as it operates at frequencies greater than 1,000 Hz). During those trials, fin whales, sperm whales, Sowerby's beaked whales, long- finned pilot whales, Atlantic white-sided dolphins, and common bottlenose dolphins were observed and their vocalizations were recorded. These monitoring studies detected no evidence of behavioral responses that the investigators could attribute to exposure to the low-frequency active sonar during these trials. Explosive Sources Underwater explosive detonations send a shock wave and sound energy through the water and can release gaseous by-products, create an oscillating bubble, or cause a plume of water to shoot up from the water surface. The shock wave and accompanying noise are of most concern to marine animals. Depending on the intensity of the shock wave and size, location, and depth of the animal, an animal can be injured, killed, suffer non-lethal physical effects, experience hearing related effects with or without behavioral responses, or exhibit temporary behavioral responses or tolerance from hearing the blast sound. Generally, exposures to higher levels of impulse and pressure levels would result in greater impacts to an individual animal. [[Page 29926]] Injuries resulting from a shock wave take place at boundaries between tissues of different densities. Different velocities are imparted to tissues of different densities, and this can lead to their physical disruption. Blast effects are greatest at the gas-liquid interface (Landsberg, 2000). Gas-containing organs, particularly the lungs and gastrointestinal tract, are especially susceptible (Goertner, 1982; Hill, 1978; Yelverton et al., 1973). Intestinal walls can bruise or rupture, with subsequent hemorrhage and escape of gut contents into the body cavity. Less severe gastrointestinal tract injuries include contusions, petechiae (small red or purple spots caused by bleeding in the skin), and slight hemorrhaging (Yelverton et al., 1973). Because the ears are the most sensitive to pressure, they are the organs most sensitive to injury (Ketten, 2000). Sound-related damage associated with sound energy from detonations can be theoretically distinct from injury from the shock wave, particularly farther from the explosion. If a noise is audible to an animal, it has the potential to damage the animal's hearing by causing decreased sensitivity (Ketten, 1995). Lethal impacts are those that result in immediate death or serious debilitation in or near an intense source and are not, technically, pure acoustic trauma (Ketten, 1995). Sublethal impacts include hearing loss, which is caused by exposures to perceptible sounds. Severe damage (from the shock wave) to the ears includes tympanic membrane rupture, fracture of the ossicles, damage to the cochlea, hemorrhage, and cerebrospinal fluid leakage into the middle ear. Moderate injury implies partial hearing loss due to tympanic membrane rupture and blood in the middle ear. Permanent hearing loss also can occur when the hair cells are damaged by one very loud event, as well as by prolonged exposure to a loud noise or chronic exposure to noise. The level of impact from blasts depends on both an animal's location and, at outer zones, on its sensitivity to the residual noise (Ketten, 1995). Further Potential Effects of Behavioral Disturbance on Marine Mammal Fitness The different ways that marine mammals respond to sound are sometimes indicators of the ultimate effect that exposure to a given stimulus will have on the well-being (survival, reproduction, etc.) of an animal. There are few quantitative marine mammal data relating the exposure of marine mammals to sound to effects on reproduction or survival, though data exists for terrestrial species to which we can draw comparisons for marine mammals. Several authors have reported that disturbance stimuli may cause animals to abandon nesting and foraging sites (Sutherland and Crockford, 1993); may cause animals to increase their activity levels and suffer premature deaths or reduced reproductive success when their energy expenditures exceed their energy budgets (Daan et al., 1996; Feare, 1976; Mullner et al., 2004); or may cause animals to experience higher predation rates when they adopt risk-prone foraging or migratory strategies (Frid and Dill, 2002). Each of these studies addressed the consequences of animals shifting from one behavioral state (e.g., resting or foraging) to another behavioral state (e.g., avoidance or escape behavior) because of human disturbance or disturbance stimuli. One consequence of behavioral avoidance results in the altered energetic expenditure of marine mammals because energy is required to move and avoid surface vessels or the sound field associated with active sonar (Frid and Dill, 2002). Most animals can avoid that energetic cost by swimming away at slow speeds or speeds that minimize the cost of transport (Miksis-Olds, 2006), as has been demonstrated in Florida manatees (Miksis-Olds, 2006). Those energetic costs increase, however, when animals shift from a resting state, which is designed to conserve an animal's energy, to an active state that consumes energy the animal would have conserved had it not been disturbed. Marine mammals that have been disturbed by anthropogenic noise and vessel approaches are commonly reported to shift from resting to active behavioral states, which would imply that they incur an energy cost. Morete et al. (2007) reported that undisturbed humpback whale cows that were accompanied by their calves were frequently observed resting while their calves circled them (milling). When vessels approached, the amount of time cows and calves spent resting and milling, respectively, declined significantly. These results are similar to those reported by Scheidat et al. (2004) for the humpback whales they observed off the coast of Ecuador. Constantine and Brunton (2001) reported that bottlenose dolphins in the Bay of Islands, New Zealand engaged in resting behavior just 5 percent of the time when vessels were within 300 m, compared with 83 percent of the time when vessels were not present. However, Heenehan et al. (2016) report that results of a study of the response of Hawaiian spinner dolphins to human disturbance suggest that the key factor is not the sheer presence or magnitude of human activities, but rather the directed interactions and dolphin-focused activities that elicit responses from dolphins at rest. This information again illustrates the importance of context in regard to whether an animal will respond to a stimulus. Miksis-Olds (2006) and Miksis-Olds et al. (2005) reported that Florida manatees in Sarasota Bay, Florida, reduced the amount of time they spent milling and increased the amount of time they spent feeding when background noise levels increased. Although the acute costs of these changes in behavior are not likely to exceed an animal's ability to compensate, the chronic costs of these behavioral shifts are uncertain. Attention is the cognitive process of selectively concentrating on one aspect of an animal's environment while ignoring other things (Posner, 1994). Because animals (including humans) have limited cognitive resources, there is a limit to how much sensory information they can process at any time. The phenomenon called ``attentional capture'' occurs when a stimulus (usually a stimulus that an animal is not concentrating on or attending to) ``captures'' an animal's attention. This shift in attention can occur consciously or subconsciously (for example, when an animal hears sounds that it associates with the approach of a predator) and the shift in attention can be sudden (Dukas, 2002; van Rij, 2007). Once a stimulus has captured an animal's attention, the animal can respond by ignoring the stimulus, assuming a ``watch and wait'' posture, or treat the stimulus as a disturbance and respond accordingly, which includes scanning for the source of the stimulus or ``vigilance'' (Cowlishaw et al., 2004). Vigilance is normally an adaptive behavior that helps animals determine the presence or absence of predators, assess their distance from conspecifics, or to attend cues from prey (Bednekoff and Lima, 1998; Treves, 2000). Despite those benefits, however, vigilance has a cost of time; when animals focus their attention on specific environmental cues, they are not attending to other activities such as foraging. These costs have been documented best in foraging animals, where vigilance has been shown to substantially reduce feeding rates (Saino, 1994; Beauchamp and Livoreil, 1997; Fritz et al., 2002). Animals will spend more time being vigilant, which may translate to less time foraging or resting, when disturbance stimuli approach them more directly, remain at closer distances, have a greater group size (e.g., [[Page 29927]] multiple surface vessels), or when they co-occur with times that an animal perceives increased risk (e.g., when they are giving birth or accompanied by a calf). Most of the published literature, however, suggests that direct approaches will increase the amount of time animals will dedicate to being vigilant. An example of this concept with terrestrial species involved bighorn sheep and Dall's sheep, which dedicated more time being vigilant, and less time resting or foraging, when aircraft made direct approaches over them (Frid, 2001; Stockwell et al., 1991). Vigilance has also been documented in pinnipeds at haul out sites where resting may be disturbed when seals become alerted and/ or flush into the water due to a variety of disturbances, which may be anthropogenic (noise and/or visual stimuli) or due to other natural causes such as other pinnipeds (Richardson et al., 1995; Southall et al., 2007; VanBlaricom, 2010; and Lozano and Hente, 2014). Several authors have established that long-term and intense disturbance stimuli can cause population declines by reducing the physical condition of individuals that have been disturbed, followed by reduced reproductive success, reduced survival, or both (Daan et al., 1996; Madsen, 1994; White, 1985). For example, Madsen (1994) reported that pink-footed geese (Anser brachyrhynchus) in undisturbed habitat gained body mass and had about a 46 percent reproductive success rate compared with geese in disturbed habitat (being consistently scared off the fields on which they were foraging) which did not gain mass and had a 17 percent reproductive success rate. Similar reductions in reproductive success have been reported for mule deer (Odocoileus hemionus) disturbed by all-terrain vehicles (Yarmoloy et al., 1988), caribou (Rangifer tarandus caribou) disturbed by seismic exploration blasts (Bradshaw et al., 1998), and caribou disturbed by low-elevation military jet fights (Luick et al., 1996, Harrington and Veitch, 1992). Similarly, a study of elk (Cervus elaphus) that were disturbed experimentally by pedestrians concluded that the ratio of young to mothers was inversely related to disturbance rate (Phillips and Alldredge, 2000). The primary mechanism by which increased vigilance and disturbance appear to affect the fitness of individual animals is by disrupting an animal's time budget and, as a result, reducing the time they might spend foraging and resting (which increases an animal's activity rate and energy demand while decreasing their caloric intake/energy). Ridgway et al. (2006) reported that increased vigilance in bottlenose dolphins exposed to sound over a five-day period in open-air, open- water enclosures in San Diego Bay did not cause any sleep deprivation or stress effects such as changes in cortisol or epinephrine levels. An example of this concept with terrestrial species involved a study of grizzly bears (Ursus horribilis) that reported that bears disturbed by hikers reduced their energy intake by an average of 12 kilocalories/min (50.2 x 103 kiloJoules/min), and spent energy fleeing or acting aggressively toward hikers (White et al., 1999). Lusseau and Bejder (2007) present data from three long-term studies illustrating the connections between disturbance from whale-watching boats and population-level effects in cetaceans. In Sharks Bay Australia, the abundance of bottlenose dolphins was compared within adjacent control and tourism sites over three consecutive 4.5-year periods of increasing tourism levels. Between the second and third time periods, in which tourism doubled, dolphin abundance decreased by 15 percent in the tourism area and did not change significantly in the control area. In Fiordland, New Zealand, two populations (Milford and Doubtful Sounds) of bottlenose dolphins with tourism levels that differed by a factor of seven were observed and significant increases in travelling time and decreases in resting time were documented for both. Consistent short-term avoidance strategies were observed in response to tour boats until a threshold of disturbance was reached (average 68 minutes between interactions), after which the response switched to a longer-term habitat displacement strategy. For one population, tourism only occurred in a part of the home range. However, tourism occurred throughout the home range of the Doubtful Sound population and once boat traffic increased beyond the 68-minute threshold (resulting in abandonment of their home range/preferred habitat), reproductive success drastically decreased (increased stillbirths) and abundance decreased significantly (from 67 to 56 individuals in short period). Last, in a study of northern resident killer whales off Vancouver Island, exposure to boat traffic was shown to reduce foraging opportunities and increase traveling time. A simple bioenergetics model was applied to show that the reduced foraging opportunities equated to a decreased energy intake of 18 percent, while the increased traveling incurred an increased energy output of 3-4 percent, which suggests that a management action based on avoiding interference with foraging might be particularly effective. On a related note, many animals perform vital functions, such as feeding, resting, traveling, and socializing, on a diel cycle (24-hr cycle). Behavioral reactions to noise exposure (such as disruption of critical life functions, displacement, or avoidance of important habitat) are more likely to be significant for fitness if they last more than one diel cycle or recur on subsequent days (Southall et al., 2007). Consequently, a behavioral response lasting less than one day and not recurring on subsequent days is not considered particularly severe unless it could directly affect reproduction or survival (Southall et al., 2007). It is important to note the difference between behavioral reactions lasting or recurring over multiple days and anthropogenic activities lasting or recurring over multiple days. For example, just because an at-sea exercises last for multiple days does not necessarily mean that individual animals will be exposed to those exercises for multiple days or exposed in a manner that would result in a sustained behavioral response. In order to understand how the effects of activities may or may not impact species and stocks of marine mammals, it is necessary to understand not only what the likely disturbances are going to be, but how those disturbances may affect the reproductive success and survivorship of individuals, and then how those impacts to individuals translate to population-level effects. Following on the earlier work of a committee of the U.S. National Research Council (NRC, 2005), New et al. (2014), in an effort termed the Potential Consequences of Disturbance (PCoD), outline an updated conceptual model of the relationships linking disturbance to changes in behavior and physiology, health, vital rates, and population dynamics. In this framework, behavioral and physiological changes can either have direct (acute) effects on vital rates, such as when changes in habitat use or increased stress levels raise the probability of mother-calf separation or predation; they can have indirect and long-term (chronic) effects on vital rates, such as when changes in time/energy budgets or increased disease susceptibility affect health, which then affects vital rates; or they can have no effect to vital rates (New et al., 2014). In addition to outlining this general framework and compiling the relevant literature that supports it, authors have [[Page 29928]] chosen four example species for which extensive long-term monitoring data exist (southern elephant seals, North Atlantic right whales, Ziphidae beaked whales, and bottlenose dolphins) and developed state- space energetic models that can be used to effectively forecast longer- term, population-level impacts from behavioral changes. While these are very specific models with very specific data requirements that cannot yet be applied broadly to project-specific risk assessments for the majority of species, they are a critical first step towards being able to quantify the likelihood of a population level effect. Stranding and Mortality The definition for a stranding under title IV of the MMPA is that (A) a marine mammal is dead and is (i) on a beach or shore of the United States; or (ii) in waters under the jurisdiction of the United States (including any navigable waters); or (B) a marine mammal is alive and is (i) on a beach or shore of the United States and is unable to return to the water; (ii) on a beach or shore of the United States and, although able to return to the water, is in need of apparent medical attention; or (iii) in the waters under the jurisdiction of the United States (including any navigable waters), but is unable to return to its natural habitat under its own power or without assistance (16 U.S.C. 1421h). Marine mammal strandings have been linked to a variety of causes, such as illness from exposure to infectious agents, biotoxins, or parasites; starvation; unusual oceanographic or weather events; or anthropogenic causes including fishery interaction, ship strike, entrainment, entrapment, sound exposure, or combinations of these stressors sustained concurrently or in series. Historically, the cause or causes of most strandings have remained unknown (Geraci et al., 1976; Eaton, 1979, Odell et al., 1980; Best, 1982), but the development of trained, professional stranding response networks and improved analyses have led to a greater understanding of marine mammal stranding causes (Simeone and Moore in press). Numerous studies suggest that the physiology, behavior, habitat, social, relationships, age, or condition of cetaceans may cause them to strand or might pre-dispose them to strand when exposed to another phenomenon. These suggestions are consistent with the conclusions of numerous other studies that have demonstrated that combinations of dissimilar stressors commonly combine to kill an animal or dramatically reduce its fitness, even though one exposure without the other does not produce the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003; Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a; 2005b, Romero, 2004; Sih et al., 2004). Historically, stranding reporting and response efforts have been inconsistent, although significant improvements have occurred over the last 25 years. Reporting forms for basic (``Level A'') information, rehabilitation disposition, and Human Interaction have been standardized nationally (available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/level-data-collection-marine-mammal-stranding-events). However, data collected beyond basic information varies by region (and may vary from case to case), and are not standardized across the United States. Logistical conditions such as weather, time, location, and decomposition state may also affect the ability of the stranding network to thoroughly examine a specimen (Carretta et al., 2016b; Moore et al., 2013). While the investigation of stranded animals provides insight into the types of threats marine mammal populations face, full investigations are only possible and conducted on a small fraction of the total number of strandings that occur, limiting our understanding of the causes of strandings (Carretta et al., 2016a). Additionally, and due to the variability in effort and data collected, the ability to interpret long-term trends in stranded marine mammals is complicated. Along the coasts of the continental United States and Alaska between 2001 and 2009, there were on average approximately 12,545 cetacean strandings and 39,104 pinniped strandings (51,649 total) per year (National Marine Fisheries Service, 2016i). Several mass strandings (strandings that involve two or more individuals of the same species, excluding a single mother-calf pair) that have occurred over the past two decades have been associated with anthropogenic activities that introduced sound into the marine environment such as naval operations and seismic surveys. An in-depth discussion of strandings is in the Navy's Technical Report on Marine Mammal Strandings Associated with U.S. Navy Sonar Activities (U.S. Navy Marine Mammal Program & Space and Naval Warfare Systems Command Center Pacific, 2017). Worldwide, there have been several efforts to identify relationships between cetacean mass stranding events and military active sonar (Cox et al., 2006, Hildebrand, 2004; IWC, 2005; Taylor et al., 2004). For example, based on a review of mass stranding events around the world consisting of two or more individuals of Cuvier's beaked whales, records from the International Whaling Commission (IWC)(2005) show that a quarter (9 of 41) were associated with concurrent naval patrol, explosion, maneuvers, or MFAS. D'Amico et al. (2009) reviewed beaked whale stranding data compiled primarily from the published literature, which provides an incomplete record of stranding events, as many are not written up for publication, along with unpublished information from some regions of the world. Most of the stranding events reviewed by the IWC involved beaked whales. A mass stranding of Cuvier's beaked whales in the eastern Mediterranean Sea occurred in 1996 (Frantzis, 1998) and mass stranding events involving Gervais' beaked whales, Blainville's beaked whales, and Cuvier's beaked whales occurred off the coast of the Canary Islands in the late 1980s (Simmonds and Lopez-Jurado, 1991). The stranding events that occurred in the Canary Islands and Kyparissiakos Gulf in the late 1990s and the Bahamas in 2000 have been the most intensively- studied mass stranding events and have been associated with naval maneuvers involving the use of tactical sonar. Other cetacean species with naval sonar implicated in stranding events include harbor porpoise (Phocoena phocoena) (Norman et al., 2004, Wright et al., 2013) and common dolphin (Delphinus delphis) (Jepson and Deaville 2009). Strandings Associated With Impulsive Sound Silver Strand During a Navy training event on March 4, 2011 at the Silver Strand Training Complex in San Diego, California, three or possibly four dolphins were killed in an explosion. During an underwater detonation training event, a pod of 100 to 150 long-beaked common dolphins were observed moving towards the 700-yd (640.1 m) exclusion zone around the explosive charge, monitored by personnel in a safety boat and participants in a dive boat. Approximately five minutes remained on a time-delay fuse connected to a single 8.76 lb (3.97 kg) explosive charge (C-4 and detonation cord). Although the dive boat was placed between the pod and the explosive in an effort to guide the dolphins away from the area, that effort was unsuccessful and three long-beaked common dolphins near the [[Page 29929]] explosion died. In addition to the three dolphins found dead on March 4, the remains of a fourth dolphin were discovered on March 7, 2011 near Oceanside, California (3 days later and approximately 68 km north of the detonation), which might also have been related to this event. Association of the fourth stranding with the training event is uncertain because dolphins strand on a regular basis in the San Diego area. Details such as the dolphins' depth and distance from the explosive at the time of the detonation could not be estimated from the 250 yd (228.6 m) standoff point of the observers in the dive boat or the safety boat. These dolphin mortalities are the only known occurrence of a U.S. Navy training or testing event involving impulsive energy (underwater detonation) that caused mortality or injury to a marine mammal. Despite this being a rare occurrence, the Navy has reviewed training requirements, safety procedures, and possible mitigation measures and implemented changes to reduce the potential for this to occur in the future. Discussions of procedures associated with underwater explosives training and other training events are presented in the Proposed Mitigation section. Kyle of Durness, Scotland On July 22, 2011 a mass stranding event involving long-finned pilot whales occurred at Kyle of Durness, Scotland. An investigation by Brownlow et al. (2015) considered unexploded ordnance detonation activities at a Ministry of Defense bombing range, conducted by the Royal Navy prior to and during the strandings, as a plausible contributing factor in the mass stranding event. While Brownlow et al. (2015) concluded that the serial detonations of underwater ordnance were an influential factor in the mass stranding event (along with presence of a potentially compromised animal and navigational error in a topographically complex region) they also suggest that mitigation measures--which included observations from a zodiac only and by personnel not experienced in marine mammal observation, among other deficiencies--were likely insufficient to assess if cetaceans were in the vicinity of the detonations. The authors also cite information from the Ministry of Defense indicating ``an extraordinarily high level of activity'' (i.e., frequency and intensity of underwater explosions) on the range in the days leading up to the stranding. Gulf of California, Mexico One stranding event was contemporaneous with and reasonably associated spatially with the use of seismic air guns. This event occurred in the Gulf of California, coincident with seismic reflection profiling by the R/V Maurice Ewing operated by Columbia University's Lamont-Doherty Earth Observatory and involved two Cuvier's beaked whales (Hildebrand, 2004). The vessel had been firing an array of 20 air guns with a total volume of 8,500 in\3\ (Hildebrand, 2004; Taylor et al., 2004). Strandings Associated With Active Sonar Over the past 21 years, there have been five stranding events coincident with military MF active sonar use in which exposure to sonar is believed to have been a contributing factor: Greece (1996); the Bahamas (2000); Madeira (2000); Canary Islands (2002); and Spain (2006) (Cox et al., 2006; Fernandez, 2006; U.S. Navy Marine Mammal Program & Space and Naval Warfare Systems Command Center Pacific, 2017). These five mass strandings have resulted in about 40 known cetacean deaths consisting mostly of beaked whales and with close linkages to mid- frequency active sonar activity. In these circumstances, exposure to non-impulsive acoustic energy was considered a potential indirect cause of death of the marine mammals (Cox et al., 2006). Only one of these stranding events, the Bahamas (2000), was associated with exercises conducted by the U.S. Navy. Additionally, in 2004, during the Rim of the Pacific (RIMPAC) exercises, between 150 and 200 usually pelagic melon-headed whales occupied the shallow waters of Hanalei Bay, Kauai, Hawaii for over 28 hours. NMFS determined that MFAS was a plausible, if not likely, contributing factor in what may have been a confluence of events that led to the Hanalei Bay stranding. A number of other stranding events coincident with the operation of MFAS, including the death of beaked whales or other species (minke whales, dwarf sperm whales, pilot whales), have been reported; however, the majority have not been investigated to the degree necessary to determine the cause of the stranding. Most recently, the Independent Scientific Review Panel investigating potential contributing factors to a 2008 mass stranding of melon-headed whales in Antsohihy, Madagascar released its final report suggesting that the stranding was likely initially triggered by an industry seismic survey. This report suggests that the operation of a commercial high-powered 12 kHz multi-beam echosounder during an industry seismic survey was a plausible and likely initial trigger that caused a large group of melon-headed whales to leave their typical habitat and then ultimately strand as a result of secondary factors such as malnourishment and dehydration. The report indicates that the risk of this particular convergence of factors and ultimate outcome is likely very low, but recommends that the potential be considered in environmental planning. Because of the association between tactical mid-frequency active sonar use and a small number of marine mammal strandings, the Navy and NMFS have been considering and addressing the potential for strandings in association with Navy activities for years. In addition to the proposed mitigation measures intended to more broadly minimize impacts to marine mammals, the Navy will abide by the Notification and Reporting Plan, which sets out notification, reporting, and other requirements when dead, injured, or stranding whales are detected in certain circumstances. Greece (1996) Twelve Cuvier's beaked whales stranded atypically (in both time and space) along a 38.2-km strand of the Kyparissiakos Gulf coast on May 12 and 13, 1996 (Frantzis, 1998). From May 11 through May 15, the North Atlantic Treaty Organization (NATO) research vessel Alliance was conducting sonar tests with signals of 600 Hz and 3 kHz and source levels of 228 and 226 dB re: 1[mu]Pa, respectively (D'Amico and Verboom, 1998; D'Spain et al., 2006). The timing and location of the testing encompassed the time and location of the strandings (Frantzis, 1998). Necropsies of eight of the animals were performed but were limited to basic external examination and sampling of stomach contents, blood, and skin. No ears or organs were collected, and no histological samples were preserved. No apparent abnormalities or wounds were found. Examination of photos of the animals, taken soon after their death, revealed that the eyes of at least four of the individuals were bleeding. Photos were taken soon after their death (Frantzis, 2004). Stomach contents contained the flesh of cephalopods, indicating that feeding had recently taken place (Frantzis, 1998). All available information regarding the conditions associated with this stranding event were compiled, and many potential causes were examined including major pollution events, prominent tectonic activity, unusual [[Page 29930]] physical or meteorological events, magnetic anomalies, epizootics, and conventional military activities (International Council for the Exploration of the Sea, 2005a). However, none of these potential causes coincided in time or space with the mass stranding, or could explain its characteristics (International Council for the Exploration of the Sea, 2005a). The robust condition of the animals, plus the recent stomach contents, is inconsistent with pathogenic causes. In addition, environmental causes can be ruled out as there were no unusual environmental circumstances or events before or during this time period and within the general proximity (Frantzis, 2004). Because of the rarity of this mass stranding of Cuvier's beaked whales in the Kyparissiakos Gulf (first one in historical records), the probability for the two events (the military exercises and the strandings) to coincide in time and location, while being independent of each other, was thought to be extremely low (Frantzis, 1998). However, because full necropsies had not been conducted, and no abnormalities were noted, the cause of the strandings could not be precisely determined (Cox et al., 2006). A Bioacoustics Panel convened by NATO concluded that the evidence available did not allow them to accept or reject sonar exposures as a causal agent in these stranding events. The analysis of this stranding event provided support for, but no clear evidence for, the cause-and-effect relationship of tactical sonar training activities and beaked whale strandings (Cox et al., 2006). Bahamas (2000) NMFS and the Navy prepared a joint report addressing the multi- species stranding in the Bahamas in 2000, which took place within 24 hrs of U.S. Navy ships using MFAS as they passed through the Northeast and Northwest Providence Channels on March 15-16, 2000. The ships, which operated both AN/SQS-53C and AN/SQS-56, moved through the channel while emitting sonar pings approximately every 24 seconds. Of the 17 cetaceans that stranded over a 36-hr period (Cuvier's beaked whales, Blainville's beaked whales, minke whales, and a spotted dolphin), seven animals died on the beach (five Cuvier's beaked whales, one Blainville's beaked whale, and the spotted dolphin), while the other 10 were returned to the water alive (though their ultimate fate is unknown). As discussed in the Bahamas report (DOC/DON, 2001), there is no likely association between the minke whale and spotted dolphin strandings and the operation of MFAS. Necropsies were performed on five of the stranded beaked whales. All five necropsied beaked whales were in good body condition, showing no signs of infection, disease, ship strike, blunt trauma, or fishery related injuries, and three still had food remains in their stomachs. Auditory structural damage was discovered in four of the whales, specifically bloody effusions or hemorrhaging around the ears. Bilateral intracochlear and unilateral temporal region subarachnoid hemorrhage, with blood clots in the lateral ventricles, were found in two of the whales. Three of the whales had small hemorrhages in their acoustic fats (located along the jaw and in the melon). A comprehensive investigation was conducted and all possible causes of the stranding event were considered, whether they seemed likely at the outset or not. Based on the way in which the strandings coincided with ongoing naval activity involving tactical MFAS use, in terms of both time and geography, the nature of the physiological effects experienced by the dead animals, and the absence of any other acoustic sources, the investigation team concluded that MFAS aboard U.S. Navy ships that were in use during the active sonar exercise in question were the most plausible source of this acoustic or impulse trauma to beaked whales. This sound source was active in a complex environment that included the presence of a surface duct, unusual and steep bathymetry, a constricted channel with limited egress, intensive use of multiple, active sonar units over an extended period of time, and the presence of beaked whales that appear to be sensitive to the frequencies produced by these active sonars. The investigation team concluded that the cause of this stranding event was the confluence of the Navy MFAS and these contributory factors working together, and further recommended that the Navy avoid operating MFAS in situations where these five factors would be likely to occur. This report does not conclude that all five of these factors must be present for a stranding to occur, nor that beaked whales are the only species that could potentially be affected by the confluence of the other factors. Based on this, NMFS believes that the operation of MFAS in situations where surface ducts exist, or in marine environments defined by steep bathymetry and/or constricted channels may increase the likelihood of producing a sound field with the potential to cause cetaceans (especially beaked whales) to strand, and therefore, suggests the need for increased vigilance while operating MFAS in these areas, especially when beaked whales (or potentially other deep divers) are likely present. Madeira, Portugal (2000) From May 10-14, 2000, three Cuvier's beaked whales were found atypically stranded on two islands in the Madeira archipelago, Portugal (Cox et al., 2006). A fourth animal was reported floating in the Madeiran waters by fisherman but did not come ashore (Woods Hole Oceanographic Institution, 2005). Joint NATO amphibious training peacekeeping exercises involving participants from 17 countries and 80 warships, took place in Portugal during May 2-15, 2000. The bodies of the three stranded whales were examined post mortem (Woods Hole Oceanographic Institution, 2005), though only one of the stranded whales was fresh enough (24 hours after stranding) to be necropsied (Cox et al., 2006). Results from the necropsy revealed evidence of hemorrhage and congestion in the right lung and both kidneys (Cox et al., 2006). There was also evidence of intercochlear and intracranial hemorrhage similar to that which was observed in the whales that stranded in the Bahamas event (Cox et al., 2006). There were no signs of blunt trauma, and no major fractures (Woods Hole Oceanographic Institution, 2005). The cranial sinuses and airways were found to be clear with little or no fluid deposition, which may indicate good preservation of tissues (Woods Hole Oceanographic Institution, 2005). Several observations on the Madeira stranded beaked whales, such as the pattern of injury to the auditory system, are the same as those observed in the Bahamas strandings. Blood in and around the eyes, kidney lesions, pleural hemorrhages, and congestion in the lungs are particularly consistent with the pathologies from the whales stranded in the Bahamas, and are consistent with stress and pressure related trauma. The similarities in pathology and stranding patterns between these two events suggest that a similar pressure event may have precipitated or contributed to the strandings at both sites (Woods Hole Oceanographic Institution, 2005). Even though no definitive causal link can be made between the stranding event and naval exercises, certain conditions may have existed in the exercise area that, in their aggregate, may have contributed to the marine mammal strandings (Freitas, 2004): Exercises were conducted in areas of at least 547 fathoms (1,000 m) depth near a shoreline where there is a rapid [[Page 29931]] change in bathymetry on the order of 547 to 3,281 fathoms (1,000 to 6,000 m) occurring across a relatively short horizontal distance (Freitas, 2004); multiple ships were operating around Madeira, though it is not known if MFAS was used, and the specifics of the sound sources used are unknown (Cox et al., 2006, Freitas, 2004); and exercises took place in an area surrounded by landmasses separated by less than 35 nmi (65 km) and at least 10 nmi (19 km) in length, or in an embayment. Exercises involving multiple ships employing MFAS near land may produce sound directed towards a channel or embayment that may cut off the lines of egress for marine mammals (Freitas, 2004). Canary Islands, Spain (2002) The southeastern area within the Canary Islands is well known for aggregations of beaked whales due to its ocean depths of greater than 547 fathoms (1,000 m) within a few hundred meters of the coastline (Fernandez et al., 2005). On September 24, 2002, 14 beaked whales were found stranded on Fuerteventura and Lanzarote Islands in the Canary Islands (International Council for Exploration of the Sea, 2005a). Seven whales died, while the remaining seven live whales were returned to deeper waters (Fernandez et al., 2005). Four beaked whales were found stranded dead over the next three days either on the coast or floating offshore. These strandings occurred within near proximity of an international naval exercise that utilized MFAS and involved numerous surface warships and several submarines. Strandings began about four hours after the onset of MFAS activity (International Council for Exploration of the Sea, 2005a; Fernandez et al., 2005). Eight Cuvier's beaked whales, one Blainville's beaked whale, and one Gervais' beaked whale were necropsied, 6 of them within 12 hours of stranding (Fernandez et al., 2005). No pathogenic bacteria were isolated from the carcasses (Jepson et al., 2003). The animals displayed severe vascular congestion and hemorrhage especially around the tissues in the jaw, ears, brain, and kidneys, displaying marked disseminated microvascular hemorrhages associated with widespread fat emboli (Jepson et al., 2003; International Council for Exploration of the Sea, 2005a). Several organs contained intravascular bubbles, although definitive evidence of gas embolism in vivo is difficult to determine after death (Jepson et al., 2003). The livers of the necropsied animals were the most consistently affected organ, which contained macroscopic gas-filled cavities and had variable degrees of fibrotic encapsulation. In some animals, cavitary lesions had extensively replaced the normal tissue (Jepson et al., 2003). Stomachs contained a large amount of fresh and undigested contents, suggesting a rapid onset of disease and death (Fernandez et al., 2005). Head and neck lymph nodes were enlarged and congested, and parasites were found in the kidneys of all animals (Fernandez et al., 2005). The association of NATO MFAS use close in space and time to the beaked whale strandings, and the similarity between this stranding event and previous beaked whale mass strandings coincident with sonar use, suggests that a similar scenario and causative mechanism of stranding may be shared between the events. Beaked whales stranded in this event demonstrated brain and auditory system injuries, hemorrhages, and congestion in multiple organs, similar to the pathological findings of the Bahamas and Madeira stranding events. In addition, the necropsy results of Canary Islands stranding event lead to the hypothesis that the presence of disseminated and widespread gas bubbles and fat emboli were indicative of nitrogen bubble formation, similar to what might be expected in decompression sickness (Jepson et al., 2003; Fern[aacute]ndez et al., 2005). Hanalei Bay (2004) On July 3 and 4, 2004, approximately 150 to 200 melon-headed whales occupied the shallow waters of the Hanalei Bay, Kauai, Hawaii for over 28 hrs. Attendees of a canoe blessing observed the animals entering the Bay in a single wave formation at 7 a.m. on July 3, 2004. The animals were observed moving back into the shore from the mouth of the Bay at 9 a.m. The usually pelagic animals milled in the shallow bay and were returned to deeper water with human assistance beginning at 9:30 a.m. on July 4, 2004, and were out of sight by 10:30 a.m. Only one animal, a calf, was known to have died following this event. The animal was noted alive and alone in the Bay on the afternoon of July 4, 2004, and was found dead in the Bay the morning of July 5, 2004. A full necropsy, magnetic resonance imaging, and computerized tomography examination were performed on the calf to determine the manner and cause of death. The combination of imaging, necropsy and histological analyses found no evidence of infectious, internal traumatic, congenital, or toxic factors. Cause of death could not be definitively determined, but it is likely that maternal separation, poor nutritional condition, and dehydration contributed to the final demise of the animal. Although it is not known when the calf was separated from its mother, the animals' movement into the Bay and subsequent milling and re-grouping may have contributed to the separation or lack of nursing, especially if the maternal bond was weak or this was an inexperienced mother with her first calf. Environmental factors, abiotic and biotic, were analyzed for any anomalous occurrences that would have contributed to the animals entering and remaining in Hanalei Bay. The Bay's bathymetry is similar to many other sites within the Hawaiian Island chain and dissimilar to sites that have been associated with mass strandings in other parts of the U.S. The weather conditions appeared to be normal for that time of year with no fronts or other significant features noted. There was no evidence of unusual distribution, occurrence of predator or prey species, or unusual harmful algal blooms, although Mobley et al. (2007) suggested that the full moon cycle that occurred at that time may have influenced a run of squid into the Bay. Weather patterns and bathymetry that have been associated with mass strandings elsewhere were not found to occur in this instance. The Hanalei event was spatially and temporally correlated with RIMPAC. Official sonar training and tracking exercises in the Pacific Missile Range Facility (PMRF) warning area did not commence until approximately 8 a.m. on July 3 and were thus ruled out as a possible trigger for the initial movement into the Bay. However, six naval surface vessels transiting to the operational area on July 2 intermittently transmitted active sonar (for approximately nine hours total from 1:15 p.m. to 12:30 a.m.) as they approached from the south. The potential for these transmissions to have triggered the whales' movement into Hanalei Bay was investigated. Analyses with the information available indicated that animals to the south and east of Kaua'i could have detected active sonar transmissions on July 2, and reached Hanalei Bay on or before 7 a.m. on July 3. However, data limitations regarding the position of the whales prior to their arrival in the Bay, the magnitude of sonar exposure, behavioral responses of melon-headed whales to acoustic stimuli, and other possible relevant factors preclude a conclusive finding regarding the role of sonar in triggering this event. Propagation modeling suggests that transmissions from sonar use during the July 3 exercise in the [[Page 29932]] PMRF warning area may have been detectable at the mouth of the Bay. If the animals responded negatively to these signals, it may have contributed to their continued presence in the Bay. The U.S. Navy ceased all active sonar transmissions during exercises in this range on the afternoon of July 3. Subsequent to the cessation of sonar use, the animals were herded out of the Bay. While causation of this stranding event may never be unequivocally determined, NMFS consider the active sonar transmissions of July 2-3, 2004, a plausible, if not likely, contributing factor in what may have been a confluence of events. This conclusion is based on the following: (1) The evidently anomalous nature of the stranding; (2) its close spatiotemporal correlation with wide-scale, sustained use of sonar systems previously associated with stranding of deep-diving marine mammals; (3) the directed movement of two groups of transmitting vessels toward the southeast and southwest coast of Kauai; (4) the results of acoustic propagation modeling and an analysis of possible animal transit times to the Bay; and (5) the absence of any other compelling causative explanation. The initiation and persistence of this event may have resulted from an interaction of biological and physical factors. The biological factors may have included the presence of an apparently uncommon, deep-diving cetacean species (and possibly an offshore, non-resident group), social interactions among the animals before or after they entered the Bay, and/or unknown predator or prey conditions. The physical factors may have included the presence of nearby deep water, multiple vessels transiting in a directed manner while transmitting active sonar over a sustained period, the presence of surface sound ducting conditions, and/or intermittent and random human interactions while the animals were in the Bay. A separate event involving melon-headed whales and rough-toothed dolphins took place over the same period of time in the Northern Mariana Islands (Jefferson et al., 2006), which is several thousand miles from Hawaii. Some 500 to 700 melon-headed whales came into Sasanhaya Bay on July 4, 2004, near the island of Rota and then left of their own accord after 5.5 hours; no known active sonar transmissions occurred in the vicinity of that event. The Rota incident led to scientific debate regarding what, if any, relationship the event had to the simultaneous events in Hawaii and whether they might be related by some common factor (e.g., there was a full moon on July 2, 2004, as well as during other melon-headed whale strandings and nearshore aggregations (Brownell et al., 2009; Lignon et al., 2007; Mobley et al., 2007). Brownell et al. (2009) compared the two incidents, along with one other stranding incident at Nuka Hiva in French Polynesia and normal resting behaviors observed at Palmyra Island, in regard to physical features in the areas, melon-headed whale behavior, and lunar cycles. Brownell et al., (2009) concluded that the rapid entry of the whales into Hanalei Bay, their movement into very shallow water far from the 100-m contour, their milling behavior (typical pre-stranding behavior), and their reluctance to leave the bay constituted an unusual event that was not similar to the events that occurred at Rota (but was similar to the events at Palmyra), which appear to be similar to observations of melon-headed whales resting normally at Palmyra Island. Additionally, there was no correlation between lunar cycle and the types of behaviors observed in the Brownell et al. (2009) examples. Spain (2006) The Spanish Cetacean Society reported an atypical mass stranding of four beaked whales that occurred January 26, 2006, on the southeast coast of Spain, near Mojacar (Gulf of Vera) in the Western Mediterranean Sea. According to the report, two of the whales were discovered the evening of January 26 and were found to be still alive. Two other whales were discovered during the day on January 27, but had already died. The first three animals were located near the town of Mojacar and the fourth animal was found dead, a few kilometers north of the first three animals. From January 25-26, 2006, Standing NATO Response Force Maritime Group Two (five of seven ships including one U.S. ship under NATO Operational Control) had conducted active sonar training against a Spanish submarine within 50 nmi (93 km) of the stranding site. Veterinary pathologists necropsied the two male and two female Cuvier's beaked whales. According to the pathologists, the most likely primary cause of this type of beaked whale mass stranding event was anthropogenic acoustic activities, most probably anti-submarine MFAS used during the military naval exercises. However, no positive acoustic link was established as a direct cause of the stranding. Even though no causal link can be made between the stranding event and naval exercises, certain conditions may have existed in the exercise area that, in their aggregate, may have contributed to the marine mammal strandings (Freitas, 2004): Exercises were conducted in areas of at least 547 fathoms (1,000 m) depth near a shoreline where there is a rapid change in bathymetry on the order of 547 to 3,281 fathoms (1,000 to 6,000 m) occurring across a relatively short horizontal distance (Freitas, 2004); multiple ships (in this instance, five) were operating MFAS in the same area over extended periods of time (in this case, 20 hours) in close proximity; and exercises took place in an area surrounded by landmasses, or in an embayment. Exercises involving multiple ships employing MFAS near land may have produced sound directed towards a channel or embayment that may have cut off the lines of egress for the affected marine mammals (Freitas, 2004). Behaviorally Mediated Responses to MFAS That May Lead to Stranding Although the confluence of Navy MFAS with the other contributory factors noted in the report was identified as the cause of the 2000 Bahamas stranding event, the specific mechanisms that led to that stranding (or the others) are not understood, and there is uncertainty regarding the ordering of effects that led to the stranding. It is unclear whether beaked whales were directly injured by sound (e.g., acoustically mediated bubble growth, as addressed above) prior to stranding or whether a behavioral response to sound occurred that ultimately caused the beaked whales to be injured and strand. Although causal relationships between beaked whale stranding events and active sonar remain unknown, several authors have hypothesized that stranding events involving these species in the Bahamas and Canary Islands may have been triggered when the whales changed their dive behavior in a startled response to exposure to active sonar or to further avoid exposure (Cox et al., 2006; Rommel et al., 2006). These authors proposed three mechanisms by which the behavioral responses of beaked whales upon being exposed to active sonar might result in a stranding event. These include the following: Gas bubble formation caused by excessively fast surfacing; remaining at the surface too long when tissues are supersaturated with nitrogen; or diving prematurely when extended time at the surface is necessary to eliminate excess nitrogen. More specifically, beaked whales that occur in deep waters that are in close proximity to shallow waters (for example, the ``canyon areas'' that are cited in the Bahamas stranding event; [[Page 29933]] see D'Spain and D'Amico, 2006), may respond to active sonar by swimming into shallow waters to avoid further exposures and strand if they were not able to swim back to deeper waters. Second, beaked whales exposed to active sonar might alter their dive behavior. Changes in their dive behavior might cause them to remain at the surface or at depth for extended periods of time which could lead to hypoxia directly by increasing their oxygen demands or indirectly by increasing their energy expenditures (to remain at depth) and increase their oxygen demands as a result. If beaked whales are at depth when they detect a ping from an active sonar transmission and change their dive profile, this could lead to the formation of significant gas bubbles, which could damage multiple organs or interfere with normal physiological function (Cox et al., 2006; Rommel et al., 2006; Zimmer and Tyack, 2007). Baird et al. (2005) found that slow ascent rates from deep dives and long periods of time spent within 50 m of the surface were typical for both Cuvier's and Blainville's beaked whales, the two species involved in mass strandings related to naval sonar. These two behavioral mechanisms may be necessary to purge excessive dissolved nitrogen concentrated in their tissues during their frequent long dives (Baird et al., 2005). Baird et al. (2005) further suggests that abnormally rapid ascents or premature dives in response to high- intensity sonar could indirectly result in physical harm to the beaked whales, through the mechanisms described above (gas bubble formation or non-elimination of excess nitrogen). Because many species of marine mammals make repetitive and prolonged dives to great depths, it has long been assumed that marine mammals have evolved physiological mechanisms to protect against the effects of rapid and repeated decompressions. Although several investigators have identified physiological adaptations that may protect marine mammals against nitrogen gas supersaturation (alveolar collapse and elective circulation; Kooyman et al., 1972; Ridgway and Howard, 1979), Ridgway and Howard (1979) reported that bottlenose dolphins that were trained to dive repeatedly had muscle tissues that were substantially supersaturated with nitrogen gas. Houser et al. (2001) used these data to model the accumulation of nitrogen gas within the muscle tissue of other marine mammal species and concluded that cetaceans that dive deep and have slow ascent or descent speeds would have tissues that are more supersaturated with nitrogen gas than other marine mammals. Based on these data, Cox et al. (2006) hypothesized that a critical dive sequence might make beaked whales more prone to stranding in response to acoustic exposures. The sequence began with (1) very deep (to depths as deep as 2 km) and long (as long as 90 minutes) foraging dives; (2) relatively slow, controlled ascents; and (3) a series of ``bounce'' dives between 100 and 400 m in depth (also see Zimmer and Tyack, 2007). They concluded that acoustic exposures that disrupted any part of this dive sequence (for example, causing beaked whales to spend more time at surface without the bounce dives that are necessary to recover from the deep dive) could produce excessive levels of nitrogen supersaturation in their tissues, leading to gas bubble and emboli formation that produces pathologies similar to decompression sickness. Zimmer and Tyack (2007) modeled nitrogen tension and bubble growth in several tissue compartments for several hypothetical dive profiles and concluded that repetitive shallow dives (defined as a dive where depth does not exceed the depth of alveolar collapse, approximately 72 m for Ziphius), perhaps as a consequence of an extended avoidance reaction to sonar sound, could pose a risk for decompression sickness and that this risk should increase with the duration of the response. Their models also suggested that unrealistically rapid rates of ascent from normal dive behaviors are unlikely to result in supersaturation to the extent that bubble formation would be expected. Tyack et al. (2006) suggested that emboli observed in animals exposed to mid-frequency range sonar (Jepson et al., 2003; Fernandez et al., 2005; Fern[aacute]ndez et al., 2012) could stem from a behavioral response that involves repeated dives shallower than the depth of lung collapse. Given that nitrogen gas accumulation is a passive process (i.e., nitrogen is metabolically inert), a bottlenose dolphin was trained to repetitively dive a profile predicted to elevate nitrogen saturation to the point that nitrogen bubble formation was predicted to occur. However, inspection of the vascular system of the dolphin via ultrasound did not demonstrate the formation of asymptomatic nitrogen gas bubbles (Houser et al., 2007). Baird et al. (2008), in a beaked whale tagging study off Hawaii, showed that deep dives are equally common during day or night, but ``bounce dives'' are typically a daytime behavior, possibly associated with visual predator avoidance. This may indicate that ``bounce dives'' are associated with something other than behavioral regulation of dissolved nitrogen levels, which would be necessary day and night. If marine mammals respond to a Navy vessel that is transmitting active sonar in the same way that they might respond to a predator, their probability of flight responses could increase when they perceive that Navy vessels are approaching them directly, because a direct approach may convey detection and intent to capture (Burger and Gochfeld, 1981, 1990; Cooper, 1997, 1998). The probability of flight responses could also increase as received levels of active sonar increase (and the ship is, therefore, closer) and as ship speeds increase (that is, as approach speeds increase). For example, the probability of flight responses in Dall's sheep (Ovis dalli dalli) (Frid 2001a, b), ringed seals (Phoca hispida) (Born et al., 1999), Pacific brant (Branta bernic nigricans) and Canada geese (B. canadensis) increased as a helicopter or fixed-wing aircraft approached groups of these animals more directly (Ward et al., 1999). Bald eagles (Haliaeetus leucocephalus) perched on trees alongside a river were also more likely to flee from a paddle raft when their perches were closer to the river or were closer to the ground (Steidl and Anthony, 1996). Despite the many theories involving bubble formation (both as a direct cause of injury (see Acoustically Mediated Bubble Growth Section) and an indirect cause of stranding (See Behaviorally Mediated Bubble Growth Section), Southall et al. (2007) summarizes that there is either scientific disagreement or a lack of information regarding each of the following important points: (1) Received acoustical exposure conditions for animals involved in stranding events; (2) pathological interpretation of observed lesions in stranded marine mammals; (3) acoustic exposure conditions required to induce such physical trauma directly; (4) whether noise exposure may cause behavioral reactions (such as atypical diving behavior) that secondarily cause bubble formation and tissue damage; and (5) the extent the post mortem artifacts introduced by decomposition before sampling, handling, freezing, or necropsy procedures affect interpretation of observed lesions. Strandings Along Southern California and Hawaii Stranding events, specifically UMEs that occurred along Southern California or Hawaii (inclusive of the HSTT Study [[Page 29934]] Area) were previously discussed in the Description of Marine Mammals section. Data were gathered from stranding networks that operate within and adjacent to the HSTT Study Area and reviewed in an attempt to better understand the frequency that marine mammal strandings occur and what major causes of strandings (both human-related and natural) exist in areas around the HSTT Study Area (NMFS, 2015a). From 2010 through 2014, there were 314 cetacean and phocid strandings reported in Hawaii, an annual average of 63 strandings per year. Twenty-seven species stranded in this region. The most common species reported include the Hawaiian monk seal, humpback whale, sperm whale, striped and spinner dolphin. Although many marine mammals likely strand due to natural or anthropogenic causes, the majority of reported type of occurrences in marine mammal strandings in the HSTT Study Area include fisheries interactions, entanglement, vessel strike and predation. Bradford and Lyman (2015) address overall threats from human activities and industries on stocks in Hawaii. In 2004, a mass out-of-habitat aggregation of melon-headed whales occurred in Hanalei Bay (see discussion above under ``Strandings Associated with Active Sonar''). It is speculated that sonar operated during a major training exercise may be related to the incident. Upon further investigation, sonar was only considered as a plausible, but not sole, contributing factor among many factors in the event. The Hanalei Bay incident does not share the characteristics observed with other mass strandings of whales coincident with sonar activity (e.g., specific traumas, species composition, etc.) (Southall et al., 2006; U.S. Navy Marine Mammal Program & Space and Naval Warfare Systems Command Center Pacific, 2017). Additional information on this event is available in the Navy's Technical Report on Marine Mammal Strandings Associated with U.S. Navy Sonar Activities (U.S. Navy Marine Mammal Program & Space and Naval Warfare Systems Command Center Pacific, 2017). In addition, on October 31, 2017, at least five pilot whales live-stranded in Nawiliwili Harbor on Kauai. NMFS has yet to determine a cause for that stranding, but Navy activities can be dismissed from consideration given there were no Navy training or testing stressors present in the area before or during the stranding (National Marine Fisheries Service, 2017b). Records for strandings in San Diego County (covering the shoreline for the Southern California portion of the HSTT Study Area) indicate that there were 143 cetacean and 1,235 pinniped strandings between 2010 and 2014, an annual average of about 29 and 247 per year, respectively. A total of 16 different species have been reported as stranded within this time frame. The majority of species reported include long-beaked common dolphins and California sea lions, but there were also reports of pacific white-sided, bottlenose and Risso's dolphins, gray, humpback, and fin whales, harbor seals and Northern elephant seals (National Marine Fisheries Service, 2015b, 2016a). However, stranded marine mammals are reported along the entire western coast of the United States each year. Within the same timeframe, there were 714 cetacean and 11,132 pinniped strandings reported outside of the Study Area, an annual average of about 142 and 2,226 respectively. Species that strand along the entire west coast are similar to those that typically strand within the Study Area with additional reports of harbor porpoise, Dall's porpoise, Steller sea lions, and various fur seals. The most common reported type of occurrence in stranded marine mammals in this region include fishery interactions, illness, predation, and vessel strikes (NMFS, 2016a). It is important to note that the mass stranding of pinnipeds along the west coast considered part of a NMFS declared UME are still being evaluated. The likely cause of this event is the lack of available prey near rookeries due to warming ocean temperatures (NOAA, 2016a). Carretta et al. (2013b; 2016b) provide additional information and data on the threats from human-related activities and the potential causes of strandings for the U.S. Pacific coast marine mammal stocks. Potential Effects of Vessel Strike Vessel collisions with marine mammals, also referred to as vessel strikes or ship strikes, can result in death or serious injury of the animal. Wounds resulting from ship strike may include massive trauma, hemorrhaging, broken bones, or propeller lacerations (Knowlton and Kraus, 2001). An animal at the surface could be struck directly by a vessel, a surfacing animal could hit the bottom of a vessel, or an animal just below the surface could be cut by a vessel's propeller. Superficial strikes may not kill or result in the death of the animal. Lethal interactions are typically associated with large whales, which are occasionally found draped across the bulbous bow of large commercial ships upon arrival in port. Although smaller cetaceans are more maneuverable in relation to large vessels than are large whales, they may also be susceptible to strike. The severity of injuries typically depends on the size and speed of the vessel (Knowlton and Kraus, 2001; Laist et al., 2001; Vanderlaan and Taggart, 2007; Conn and Silber, 2013). Impact forces increase with speed, as does the probability of a strike at a given distance (Silber et al., 2010; Gende et al., 2011). The most vulnerable marine mammals are those that spend extended periods of time at the surface in order to restore oxygen levels within their tissues after deep dives (e.g., the sperm whale). In addition, some baleen whales, seem generally unresponsive to vessel sound, making them more susceptible to vessel collisions (Nowacek et al., 2004). These species are primarily large, slow moving whales. Marine mammal responses to vessels may include avoidance and changes in dive pattern (NRC, 2003). An examination of all known ship strikes from all shipping sources (civilian and military) indicates vessel speed is a principal factor in whether a vessel strike results in death or serious injury (Knowlton and Kraus, 2001; Laist et al., 2001; Jensen and Silber, 2003; Pace and Silber, 2005; Vanderlaan and Taggart, 2007). In assessing records in which vessel speed was known, Laist et al. (2001) found a direct relationship between the occurrence of a whale strike and the speed of the vessel involved in the collision. The authors concluded that most deaths occurred when a vessel was traveling in excess of 13 kn. Jensen and Silber (2003) detailed 292 records of known or probable ship strikes of all large whale species from 1975 to 2002. Of these, vessel speed at the time of collision was reported for 58 cases. Of these 58 cases, 39 (or 67 percent) resulted in serious injury or death (19 of those resulted in serious injury as determined by blood in the water, propeller gashes or severed tailstock, and fractured skull, jaw, vertebrae, hemorrhaging, massive bruising or other injuries noted during necropsy and 20 resulted in death). Operating speeds of vessels that struck various species of large whales ranged from 2 to 51 kn. The majority (79 percent) of these strikes occurred at speeds of 13 kn or greater. The average speed that resulted in serious injury or death was 18.6 kn. Pace and Silber (2005) found that the probability of death or serious injury increased rapidly with increasing vessel speed. Specifically, the predicted probability of serious injury or death increased from 45 to 75 percent as vessel speed increased from 10 to 14 kn, and exceeded 90 percent at 17 kn. Higher [[Page 29935]] speeds during collisions result in greater force of impact and also appear to increase the chance of severe injuries or death. While modeling studies have suggested that hydrodynamic forces pulling whales toward the vessel hull increase with increasing speed (Clyne, 1999; Knowlton et al., 1995), this is inconsistent with Silber et al. (2010), which demonstrated that there is no such relationship (i.e., hydrodynamic forces are independent of speed). In a separate study, Vanderlaan and Taggart (2007) analyzed the probability of lethal mortality of large whales at a given speed, showing that the greatest rate of change in the probability of a lethal injury to a large whale as a function of vessel speed occurs between 8.6 and 15 kn. The chances of a lethal injury decline from approximately 80 percent at 15 kn to approximately 20 percent at 8.6 kn. At speeds below 11.8 kn, the chances of lethal injury drop below 50 percent, while the probability asymptotically increases toward 100 percent above 15 kn. The Jensen and Silber (2003) report notes that the database represents a minimum number of collisions, because the vast majority probably goes undetected or unreported. In contrast, Navy vessels are likely to detect any strike that does occur because of the required personnel training and lookouts (as described in the Proposed Mitigation Measures section), and they are required to report all ship strikes involving marine mammals. Overall, the percentage of Navy traffic relative to overall large shipping traffic are very small (on the order of two percent) and therefore represent a correspondingly smaller threat of potential ship strikes when compared to commercial shipping. In the SOCAL portion of the HSTT Study Area, the Navy has struck a total of 16 marine mammals in the 20-year period from 1991 through 2010 for an average of one per year. Of the 16 Navy vessel strikes over the 20-year period in SOCAL, there were seven mortalities and nine injuries reported. The vessel struck species include: Two mortalities and eight injuries of unknown species, three mortalities of gray whales (one in 1993 and two in 1998), one mortality of a blue whale in 2004, and one morality and one injury of fin whales in 2009. In the HRC portion of the HSTT Study Area, the Navy struck a total of five marine mammals in the 20-year period from 1991 through 2010, for an average of zero to one per year. Of the five Navy vessel strikes over the 20-year period in the HRC, all were reported as injuries. The vessel struck species include: one humpback whale in 1998, one unknown species and one humpback whale in 2003, one sperm whale in 2007, and an unknown species in 2008. No more than two whales were struck by Navy vessels in any given year in the HRC portion of the HSTT within the last 20 years. There was only one 12-month period in 20 years in the HRC when two whales were struck in a single year (2003). Overall, there have been zero documented vessel strikes associated with training and testing in the SOCAL and HRC portions of the HSTT Study Area since 2010 and 2008, respectively. Between 2007 and 2009, the Navy developed and distributed additional training, mitigation, and reporting tools to Navy operators to improve marine mammal protection and to ensure compliance with permit requirements. In 2009, the Navy implemented Marine Species Awareness Training designed to improve effectiveness of visual observation for marine resources including marine mammals. In subsequent years, the Navy issued refined policy guidance on ship strikes in order to collect the most accurate and detailed data possible in response to a possible incident (also see the Notification and Reporting Plan for this proposed rule). For over a decade, the Navy has implemented the Protective Measures Assessment Protocol software tool, which provides operators with notification of the required mitigation and a visual display of the planned training or testing activity location overlaid with relevant environmental data. Marine Mammal Habitat The Navy's proposed training and testing activities could potentially affect marine mammal habitat through the introduction of impacts to the prey species of marine mammals, acoustic habitat (sound in the water column), water quality, and important habitat for marine mammals. Each of these components was considered in the HSTT DEIS/OEIS and was determined by the Navy to have no effect on marine mammal habitat. Based on the information below and the supporting information included in the HSTT DEIS/OEIS, NMFS has determined that the proposed training and training activities would not have adverse or long-term impacts on marine mammal habitat. Effects to Prey Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species (e.g., crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies by species, season, and location and, for some, is not well documented. Here, we describe studies regarding the effects of noise on known marine mammal prey. Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009). The most likely effects on fishes exposed to loud, intermittent, low- frequency sounds are behavioral responses (i.e., flight or avoidance). Short duration, sharp sounds (such as pile driving or air guns) can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to acoustic sources depends on the physiological state of the fish, past exposures, motivation (e.g., feeding, spawning, migration), and other environmental factors. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure- related injuries), and mortality. Fishes, like other vertebrates, have variety of different sensory systems to glean information from ocean around them (Astrup and Mohl, 1993; Astrup, 1999; Braun and Grande, 2008; Carroll et al., 2017; Hawkins and Johnstone, 1978; Ladich and Popper, 2004; Ladich and Schulz-Mirbach, 2016; Mann, 2016; Nedwell et al., 2004; Popper et al., 2003; Popper et al., 2005). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et al., 2008) (terrestrial vertebrates generally only detect pressure). Most marine fishes primarily detect particle motion using the inner ear and lateral line system, while some fishes possess additional morphological adaptations or specializations that can enhance their sensitivity to sound pressure, such as a gas-filled swim bladder (Braun and Grande, 2008; Popper and Fay, 2011). Hearing capabilities vary considerably between different fish species with data only available for just over 100 species out of the 34,000 marine and freshwater fish species (Eschmeyer and Fong 2016). In order to better understand acoustic impacts on fishes, fish hearing groups are defined by species that possess a similar continuum of anatomical features which result in varying degrees of hearing sensitivity (Popper and Hastings, 2009a). There are four hearing groups defined for all fish species (modified from Popper et al., 2014) within this analysis and they include: Fishes without a swim bladder (e.g., flatfish, sharks, rays, etc.); fishes with a [[Page 29936]] swim bladder not involved in hearing (e.g., salmon, cod, pollock, etc.); fishes with a swim bladder involved in hearing (e.g., sardines, anchovy, herring, etc.); and fishes with a swim bladder involved in hearing and high-frequency hearing (e.g., shad and menhaden). Most marine mammal fish prey species would not be likely to perceive or hear Navy mid- or high-frequency sonars (see Figure 9-1 of the Navy's rulemaking/LOA application). Within Southern California, the Clupeiformes order of fish include the Pacific sardine (Clupeidae), and northern anchovy (Engraulidae), key forage fish in Southern California. While hearing studies have not been done on sardines and northern anchovies, it would not be unexpected for them to have hearing similarities to Pacific herring (up to 2-5 kHz) (Mann et al., 2005). Currently, less data are available to estimate the range of best sensitivity for fishes without a swim bladder. In terms of physiology, multiple scientific studies have documented a lack of mortality or physiological effects to fish from exposure to low- and mid-frequency sonar and other sounds (Halvorsen et al., 2012; J[oslash]rgensen et al., 2005; Juanes et al., 2017; Kane et al., 2010; Kvadsheim and Sevaldsen, 2005; Popper et al., 2007; Popper et al., 2016; Watwood et al., 2016). Techer et al. (2017) exposed carp in floating cages for up to 30 days to low-power 23 and 46 kHz source without any significant physiological response. Other studies have documented either a lack of TTS in species whose hearing range cannot perceive Navy sonar, or for those species that could perceive sonar-like signals, any TTS experienced would be recoverable (Halvorsen et al., 2012; Ladich and Fay, 2013; Popper and Hastings, 2009a, 2009b; Popper et al., 2014; Smith, 2016). Only fishes that have specializations that enable them to hear sounds above about 2,500 Hz (2.5 kHz) such as herring (Halvorsen et al., 2012; Mann et al., 2005; Mann, 2016; Popper et al., 2014) would have the potential to receive TTS or exhibit behavioral responses from exposure to mid-frequency sonar. In addition, any sonar induced TTS to fish whose hearing range could perceive sonar would only occur in the narrow spectrum of the source (e.g., 3.5 kHz) compared to the fish's total hearing range (e.g., 0.01 kHz to 5 kHz). Overall, Navy sonar sources are much narrower in terms of source frequency compared to a given fish species full hearing range (see examples in Figure 9-1 of the Navy's rulemaking/LOA application). In terms of behavioral responses, Juanes et al. (2017) discuss the potential for negative impacts from anthropogenic soundscapes on fish, but the author's focus was on broader based sounds such as ship and boat noise sources. Watwood et al. (2016) also documented no behavioral responses by reef fish after exposure to mid-frequency active sonar. Doksaeter et al. (2009; 2012) reported no behavioral responses to mid- frequency naval sonar by Atlantic herring, specifically, no escape reactions (vertically or horizontally) observed in free swimming herring exposed to mid-frequency sonar transmissions. Based on these results (Doksaeter et al., 2009; Doksaeter et al., 2012; Sivle et al., 2012), Sivle et al. (2014) created a model in order to report on the possible population-level effects on Atlantic herring from active naval sonar. The authors concluded that the use of naval sonar poses little risk to populations of herring regardless of season, even when the herring populations are aggregated and directly exposed to sonar. Finally, Bruintjes et al. (2016) commented that fish exposed to any short-term noise within their hearing range might initially startle, but would quickly return to normal behavior. The potential effects of air gun noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Some studies have shown no or slight reaction to air gun sounds (e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012). More commonly, though, the impacts of noise on fish are temporary. Investigators reported significant, short-term declines in commercial fishing catch rate of gadid fishes during and for up to five days after survey operations, but the catch rate subsequently returned to normal (Engas et al., 1996; Engas and Lokkeborg, 2002); other studies have reported similar findings (Hassel et al., 2004). However, even temporary effects to fish distribution patterns can impact their ability to carry out important life-history functions (Paxton et al., 2017). SPLs of sufficient strength have been known to cause injury to fish and fish mortality and, in some studies, fish auditory systems have been damaged by air gun noise (McCauley et al., 2003; Popper et al., 2005; Song et al., 2008). However, in most fish species, hair cells in the ear continuously regenerate and loss of auditory function likely is restored when damaged cells are replaced with new cells. Halvorsen et al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hrs for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. No mortality occurred to fish in any of these studies. Occasional behavioral reactions to intermittent explosions and impulsive sound sources are unlikely to cause long-term consequences for individual fish or populations. Fish that experience hearing loss as a result of exposure to explosions and impulsive sound sources may have a reduced ability to detect relevant sounds such as predators, prey, or social vocalizations. However, PTS has not been known to occur in fishes and any hearing loss in fish may be as temporary as the timeframe required to repair or replace the sensory cells that were damaged or destroyed (Popper et al., 2005; Popper et al., 2014; Smith et al., 2006). It is not known if damage to auditory nerve fibers could occur, and if so, whether fibers would recover during this process. It is also possible for fish to be injured or killed by an explosion in the immediate vicinity of the surface from dropped or fired ordnance, or near the bottom from shallow water bottom-placed underwater mine warfare detonations. Physical effects from pressure waves generated by underwater sounds (e.g., underwater explosions) could potentially affect fish within proximity of training or testing activities. The shock wave from an underwater explosion is lethal to fish at close range, causing massive organ and tissue damage and internal bleeding (Keevin and Hempen, 1997). At greater distance from the detonation point, the extent of mortality or injury depends on a number of factors including fish size, body shape, orientation, and species (Keevin and Hempen, 1997; Wright, 1982). At the same distance from the source, larger fish are generally less susceptible to death or injury, elongated forms that are round in cross-section are less at risk than deep-bodied forms, and fish oriented sideways to the blast suffer the greatest impact (Edds-Walton and Finneran, 2006; O'Keeffe, 1984; O'Keeffe and Young, 1984; Wiley et al., 1981; Yelverton et al., 1975). Species with gas-filled organs are more susceptible to injury and mortality than those without them (Gaspin, 1975; Gaspin et al., 1976; Goertner et al., 1994). Barotrauma injuries have been documented during controlled exposure to impact pile driving (an impulsive noise source, as are explosives and air guns) (Halvorsen et al., 2012b; Casper et al., 2013). For seismic surveys, the sound source is constantly moving, and most fish would likely avoid the sound [[Page 29937]] source prior to receiving sound of sufficient intensity to cause physiological or anatomical damage. Fish not killed or driven from a location by an explosion might change their behavior, feeding pattern, or distribution. Changes in behavior of fish have been observed as a result of sound produced by explosives, with effect intensified in areas of hard substrate (Wright, 1982). However, Navy explosive use avoids hard substrate to the best extent practical during underwater detonations, or deep-water surface detonations (distance from bottom). Stunning from pressure waves could also temporarily immobilize fish, making them more susceptible to predation. The abundances of various fish (and invertebrates) near the detonation point for explosives could be altered for a few hours before animals from surrounding areas repopulate the area. However, these populations would likely be replenished as waters near the detonation point are mixed with adjacent waters. Repeated exposure of individual fish to sounds from underwater explosions is not likely and are expected to be short-term and localized. Long-term consequences for fish populations would not be expected. Several studies have demonstrated that air gun sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs (e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; Paxton et al., 2017). In conclusion, for fishes exposed to Navy sonar, there would be limited sonar use spread out in time and space across large offshore areas such that only small areas are actually ensonified (10's of miles) compared to the total life history distribution of fish prey species. There would be no probability for mortality and physical injury from sonar, and for most species, no or little potential for hearing or behavioral effects, except to a few select fishes with hearing specializations (e.g., herring) that could perceive mid- frequency sonar. Training and testing exercises involving explosions are dispersed in space and time; therefore, repeated exposure of individual fishes are unlikely. Morality and injury effects to fishes from explosives would be localized around the area of a given in-water explosion, but only if individual fish and the explosive (and immediate pressure field) were co-located at the same time. Fishes deeper in the water column or on the bottom would not be affected by water surface explosions. Repeated exposure of individual fish to sound and energy from underwater explosions is not likely given fish movement patterns, especially schooling prey species. Most acoustic effects, if any, are expected to be short-term and localized. Long-term consequences for fish populations including key prey species within the HSTT Study Area would not be expected. Invertebrates appear to be able to detect sounds (Pumphrey, 1950; Frings and Frings, 1967) and are most sensitive to low-frequency sounds (Packard et al., 1990; Budelmann and Williamson, 1994; Lovell et al., 2005; Mooney et al., 2010). Data on response of invertebrates such as squid, another marine mammal prey species, to anthropogenic sound is more limited (de Soto, 2016; Sole et al., 2017b). Data suggest that cephalopods are capable of sensing the particle motion of sounds and detect low frequencies up to 1-1.5 kHz, depending on the species, and so are likely to detect air gun noise (Kaifu et al., 2008; Hu et al., 2009; Mooney et al., 2010; Samson et al., 2014). Sole et al. (2017b) reported physiological injuries to cuttlefish in cages placed at-sea when exposed during a controlled exposure experiment to low-frequency sources (315 Hz, 139 to 142 dB re 1 [mu]Pa\2\ and 400 Hz, 139 to 141 dB re 1 [mu]Pa\2\). Fewtrell and McCauley (2012) reported squids maintained in cages displayed startle responses and behavioral changes when exposed to seismic air gun sonar (136-162 re 1 [mu]Pa\2\[middot]s). However, the sources Sole et al. (2017a) and Fewtrell and McCauley (2012) used are not similar and much lower than typical Navy sources within the HSTT Study Area. Nor do the studies address the issue of individual displacement outside of a zone of impact when exposed to sound. Cephalopods have a specialized sensory organ inside the head called a statocyst that may help an animal determine its position in space (orientation) and maintain balance (Budelmann, 1992). Packard et al. (1990) showed that cephalopods were sensitive to particle motion, not sound pressure, and Mooney et al. (2010) demonstrated that squid statocysts act as an accelerometer through which particle motion of the sound field can be detected. Auditory injuries (lesions occurring on the statocyst sensory hair cells) have been reported upon controlled exposure to low-frequency sounds, suggesting that cephalopods are particularly sensitive to low- frequency sound (Andre et al., 2011; Sole et al., 2013). Behavioral responses, such as inking and jetting, have also been reported upon exposure to low-frequency sound (McCauley et al., 2000b; Samson et al., 2014). Squids, like most fish species, are likely more sensitive to low frequency sounds, and may not perceive mid- and high-frequency sonars such as Navy sonars. Cumulatively for squid as a prey species, individual and population impacts from exposure to Navy sonar and explosives, like fish, are not likely to be significant, and explosive impacts would be short-term and localized. Vessels and in-water devices do not normally collide with adult fish, most of which can detect and avoid them. Exposure of fishes to vessel strike stressors is limited to those fish groups that are large, slow-moving, and may occur near the surface, such as ocean sunfish, whale sharks, basking sharks, and manta rays. These species are distributed widely in offshore portions of the Study Area. Any isolated cases of a Navy vessel striking an individual could injure that individual, impacting the fitness of an individual fish. Vessel strikes would not pose a risk to most of the other marine fish groups, because many fish can detect and avoid vessel movements, making strikes rare and allowing the fish to return to their normal behavior after the ship or device passes. As a vessel approaches a fish, they could have a detectable behavioral or physiological response (e.g., swimming away and increased heart rate) as the passing vessel displaces them. However, such reactions are not expected to have lasting effects on the survival, growth, recruitment, or reproduction of these marine fish groups at the population level and therefore would not have an impact on marine mammals species as prey items. In addition to fish, prey sources such as marine invertebrates could potentially be impacted by sound stressors as a result of the proposed activities. However, most marine invertebrates' ability to sense sounds is very limited. In most cases, marine invertebrates would not respond to impulsive and non-impulsive sounds, although they may detect and briefly respond to nearby low-frequency sounds. These short- term responses would likely be inconsequential to invertebrate populations. Impacts to benthic communities from impulsive sound generated by active acoustic sound sources are not well documented. (e.g., Andriguetto-Filho et al., 2005; Payne et al., 2007; 2008; Boudreau et al., 2009). There are no published data that indicate whether temporary or permanent threshold shifts, auditory masking, or behavioral effects occur in benthic invertebrates (Hawkins et al., 2014) and some studies showed no [[Page 29938]] short-term or long-term effects of air gun exposure (e.g., Andriguetto- Filho et al., 2005; Payne et al., 2007; 2008; Boudreau et al., 2009). Exposure to air gun signals was found to significantly increase mortality in scallops, in addition to causing significant changes in behavioral patterns during exposure (Day et al., 2017). However, the authors state that the observed levels of mortality were not beyond naturally occurring rates. Explosions and pile driving could potentially kill or injure nearby marine invertebrates; however, mortality or long-term consequences for a few animals is unlikely to have measurable effects on overall stocks or populations. Vessels also have the potential to impact marine invertebrates by disturbing the water column or sediments, or directly striking organisms (Bishop, 2008). The propeller wash (water displaced by propellers used for propulsion) from vessel movement and water displaced from vessel hulls can potentially disturb marine invertebrates in the water column and is a likely cause of zooplankton mortality (Bickel et al., 2011). The localized and short-term exposure to explosions or vessels could displace, injure, or kill zooplankton, invertebrate eggs or larvae, and macro-invertebrates. However, mortality or long-term consequences for a few animals is unlikely to have measurable effects on overall stocks or populations. There is little information concerning potential impacts of noise on zooplankton populations. However, one recent study (McCauley et al., 2017) investigated zooplankton abundance, diversity, and mortality before and after exposure to air gun noise, finding that the exposure resulted in significant depletion for more than half the taxa present and that there were two to three times more dead zooplankton after air gun exposure compared with controls for all taxa. The majority of taxa present were copepods and cladocerans; for these taxa, the range within which effects on abundance were detected was up to approximately 1.2 km. In order to have significant impacts on r-selected species such as plankton, the spatial or temporal scale of impact must be large in comparison with the ecosystem concerned (McCauley et al., 2017). Therefore, the large scale of effect observed here is of concern-- particularly where repeated noise exposure is expected--and further study is warranted. Overall, the combined impacts of sound exposure, explosions, vessel strikes, and military expended materials resulting from the proposed activities would not be expected to have measurable effects on populations of marine mammal prey species. Prey species exposed to sound might move away from the sound source, experience TTS, experience masking of biologically relevant sounds, or show no obvious direct effects. Mortality from decompression injuries is possible in close proximity to a sound, but only limited data on mortality in response to air gun noise exposure are available (Hawkins et al., 2014). The most likely impacts for most prey species in a given area would be temporary avoidance of the area. Surveys using towed air gun arrays move through an area relatively quickly, limiting exposure to multiple impulsive sounds. In all cases, sound levels would return to ambient once a survey ends and the noise source is shut down and, when exposure to sound ends, behavioral and/or physiological responses are expected to end relatively quickly (McCauley et al., 2000b). The duration of fish avoidance of a given area after survey effort stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated. While the potential for disruption of spawning aggregations or schools of important prey species can be meaningful on a local scale, the mobile and temporary nature of most surveys and the likelihood of temporary avoidance behavior suggest that impacts would be minor. Long-term consequences to marine invertebrate populations would not be expected as a result of exposure to sounds or vessels in the Study Area. Military expended materials resulting from training and testing activities could potentially result in minor long-term changes to benthic habitat. Military expended materials may be colonized over time by benthic organisms that prefer hard substrate and would provide structure that could attract some species of fish or invertebrates. Acoustic Habitat Acoustic habitat is the soundscape which encompasses all of the sound present in a particular location and time, as a whole when considered from the perspective of the animals experiencing it. Animals produce sound for, or listen for sounds produced by, conspecifics (communication during feeding, mating, and other social activities), other animals (finding prey or avoiding predators), and the physical environment (finding suitable habitats, navigating). Together, sounds made by animals and the geophysical environment (e.g., produced by earthquakes, lightning, wind, rain, waves) make up the natural contributions to the total acoustics of a place. These acoustic conditions, termed acoustic habitat, are one attribute of an animal's total habitat. Soundscapes are also defined by, and acoustic habitat influenced by, the total contribution of anthropogenic sound. This may include incidental emissions from sources such as vessel traffic, may be intentionally introduced to the marine environment for data acquisition purposes (as in the use of air gun arrays), or for Navy training and testing purposes (as in the use of sonar and explosives and other acoustic sources). Anthropogenic noise varies widely in its frequency, content, duration, and loudness and these characteristics greatly influence the potential habitat-mediated effects to marine mammals (please also see the previous discussion on ``Masking''), which may range from local effects for brief periods of time to chronic effects over large areas and for long durations. Depending on the extent of effects to habitat, animals may alter their communications signals (thereby potentially expending additional energy) or miss acoustic cues (either conspecific or adventitious). Problems arising from a failure to detect cues are more likely to occur when noise stimuli are chronic and overlap with biologically relevant cues used for communication, orientation, and predator/prey detection (Francis and Barber, 2013). For more detail on these concepts see, e.g., Barber et al., 2009; Pijanowski et al., 2011; Francis and Barber, 2013; Lillis et al., 2014. The term ``listening area'' refers to the region of ocean over which sources of sound can be detected by an animal at the center of the space. Loss of communication space concerns the area over which a specific animal signal, used to communicate with conspecifics in biologically-important contexts (e.g., foraging, mating), can be heard, in noisier relative to quieter conditions (Clark et al., 2009). Lost listening area concerns the more generalized contraction of the range over which animals would be able to detect a variety of signals of biological importance, including eavesdropping on predators and prey (Barber et al., 2009). Such metrics do not, in and of themselves, document fitness consequences for the marine animals that live in chronically noisy environments. Long-term population-level consequences mediated through changes in the ultimate survival and reproductive success of individuals are difficult to study, and particularly so underwater. However, it is increasingly well documented that aquatic species rely on qualities of natural acoustic [[Page 29939]] habitats, with researchers quantifying reduced detection of important ecological cues (e.g., Francis and Barber, 2013; Slabbekoorn et al., 2010) as well as survivorship consequences in several species (e.g., Simpson et al., 2014; Nedelec et al., 2015). Sound produced from training and testing activities in the HSTT Study Area is temporary and transitory. The sounds produced during training and testing activities can be widely dispersed or concentrated in small areas for varying periods. Any anthropogenic noise attributed to training and testing activities in the HSTT Study Area would be temporary and the affected area would be expected to immediately return to the original state when these activities cease. Water Quality The HSTT DEIS/OEIS analyzed the potential effects on water quality from military expended materials. Training and testing activities may introduce water quality constituents into the water column. Based on the analysis of the HSTT DEIS/OEIS, military expended materials (e.g., undetonated explosive materials) would be released in quantities and at rates that would not result in a violation of any water quality standard or criteria. High-order explosions consume most of the explosive material, creating typical combustion products. For example, in the case of Royal Demolition Explosive, 98 percent of the products are common seawater constituents and the remainder is rapidly diluted below threshold effect level. Explosion by-products associated with high order detonations present no secondary stressors to marine mammals through sediment or water. However, low order detonations and unexploded ordnance present elevated likelihood of impacts on marine mammals. Indirect effects of explosives and unexploded ordnance to marine mammals via sediment is possible in the immediate vicinity of the ordnance. Degradation products of Royal Demolition Explosive are not toxic to marine organisms at realistic exposure levels (Rosen and Lotufo, 2010). Relatively low solubility of most explosives and their degradation products means that concentrations of these contaminants in the marine environment are relatively low and readily diluted. Furthermore, while explosives and their degradation products were detectable in marine sediment approximately 6-12 in (0.15-0.3 m) away from degrading ordnance, the concentrations of these compounds were not statistically distinguishable from background beyond 3-6 ft (1-2 m) from the degrading ordnance. Taken together, it is possible that marine mammals could be exposed to degrading explosives, but it would be within a very small radius of the explosive (1-6 ft (0.3-2 m)). Equipment used by the Navy within the HSTT Study Area, including ships and other marine vessels, aircraft, and other equipment, are also potential sources of by-products. All equipment is properly maintained in accordance with applicable Navy or legal requirements. All such operating equipment meets Federal water quality standards, where applicable. Estimated Take of Marine Mammals This section indicates the number of takes that NMFS is proposing to authorize which is based on the amount of take that NMFS anticipates could or is likely to occur, depending on the type of take and the methods used to estimate it, as described in detail below. NMFS coordinated closely with the Navy in the development of their incidental take application, and with one exception, preliminarily agrees that the methods the Navy has put forth described herein to estimate take (including the model, thresholds, and density estimates), and the resulting numbers estimated for authorization, are appropriate and based on the best available science. Takes are predominantly in the form of harassment, but a small number of mortalities are also estimated. For a military readiness activity, the MMPA defines ``harassment'' as (i) Any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild (Level A Harassment); or (ii) Any act that disturbs or is likely to disturb a marine mammal or marine mammal stock in the wild by causing disruption of natural behavioral patterns, including, but not limited to, migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such behavioral patterns are abandoned or significantly altered (Level B Harassment). Authorized takes would primarily be in the form of Level B harassment, as use of the acoustic and explosive sources (i.e., sonar, air guns, pile driving, explosives) is likely to result in the disruption of natural behavioral patterns to a point where they are abandoned or significantly altered (as defined specifically at the beginning of this section, but referred to generally as behavioral disruption) or TTS for marine mammals. There is also the potential for Level A harassment, in the form of auditory injury and/or tissue damage (latter for explosives only) to result from exposure to the sound sources utilized in training and testing activities. Lastly, a limited number of serious injuries or mortalities could occur for California sea lion and short-beaked common dolphin (10 mortalities total between the two species over the 5-year period) from explosives, and no more than three serious injuries or mortalities total (over the five-year period) of large whales through vessel collisions. Although we analyze the impacts of these potential serious injuries or mortalities that are proposed for authorization, the proposed mitigation and monitoring measures are expected to minimize the likelihood (i.e., further lower the already low probability) that ship strike or these explosive exposures (and the associated serious injury or mortality) occur. Described in the most basic way, we estimate the amount and type of harassment by considering: (1) Acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed (in this case, as defined in the military readiness definition included above) or incur some degree of temporary or permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the density or occurrence of marine mammals within these ensonified areas; and, (4) and the number of days during which activities might occur. Below, we describe these components in more detail and present the proposed take estimate. Acoustic Thresholds Using the best available science, and in coordination with the Navy, NMFS has established acoustic thresholds above which exposed marine mammals would reasonably be expected to experience a disruption in behavioral patterns to a point where they are abandoned or significantly altered, or to incur TTS (equated to Level B harassment) or PTS of some degree (equated to Level A harassment). Thresholds have also been developed to identify the pressure levels above which animals may incur different types of tissue damage from exposure to pressure waves from explosive detonation. Hearing Impairment (TTS/PTS and Tissue Damage and Mortality) Non-Impulsive and Impulsive NMFS's Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Technical Guidance, 2016) identifies dual criteria to assess auditory injury (Level A harassment) to five different [[Page 29940]] marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). The Technical Guidance also identifies criteria to predict TTS, which is not considered injury and falls into the Level B Harassment category. The Navy's Specified Activities includes the use of non-impulsive (sonar, vibratory pile driving/removal) sources and impulsive (explosives, air guns, impact pile driving) sources. These thresholds (Tables 14-15) were developed by compiling and synthesizing the best available science and soliciting input multiple times from both the public and peer reviewers to inform the final product, and are provided in the table below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS 2016 Technical Guidance, which may be accessed at: http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm. Table 14--Acoustic Thresholds Identifying the Onset of TTS and PTS for Non-Impulsive Sound Sources by Functional Hearing Groups ------------------------------------------------------------------------ Non-impulsive ------------------------------- Functional hearing group TTS threshold PTS threshold SEL (weighted) SEL (weighted) ------------------------------------------------------------------------ Low-Frequency Cetaceans................. 179 199 Mid-Frequency Cetaceans................. 178 198 High-Frequency Cetaceans................ 153 173 Phocid Pinnipeds (Underwater)........... 181 201 Ottarid Pinnipeds (Underwater).......... 199 219 ------------------------------------------------------------------------ Note: SEL thresholds in dB re 1 [mu]Pa\2\s. Based on the best available science, the Navy (in coordination with NMFS) used the acoustic and pressure thresholds indicated in Table 15 to predict the onset of TTS, PTS, tissue damage, and mortality for explosives (impulsive) and other impulsive sound sources. Table 15--Onset of TTS, PTS, Tissue Damage, and Mortality Thresholds for Marine Mammals for Explosives and Other Impulsive Sources -------------------------------------------------------------------------------------------------------------------------------------------------------- Mean onset Functional hearing group Species Weighted onset TTS Weighted onset PTS Mean onset slight GI slight lung Mean onset tract injury injury mortality -------------------------------------------------------------------------------------------------------------------------------------------------------- Low-frequency cetaceans........ All mysticetes.... 168 dB SEL or 213 183 dB SEL or 219 237 dB Peak SPL........ Equation 1...... Equation 2. dB Peak SPL. dB Peak SPL. Mid-frequency cetaceans........ Most delphinids, 170 dB SEL or 224 185 dB SEL or 230 237 dB Peak SPL........ medium and large dB Peak SPL. dB Peak SPL. toothed whales. High-frequency cetaceans....... Porpoises and 140 dB SEL or 196 155 dB SEL or 202 237 dB Peak SPL........ Kogia spp. dB Peak SPL. dB Peak SPL. Phocidae....................... Harbor seal, 170 dB SEL or 212 185 dB SEL or 218 237 dB Peak SPL........ Hawaiian monk dB Peak SPL. dB Peak SPL. seal, Northern elephant seal. Otariidae...................... California sea 188 dB SEL or 226 203 dB SEL or 232 237 dB Peak SPL........ lion, Guadalupe dB Peak SPL. dB Peak SPL. fur seal, Northern fur seal. -------------------------------------------------------------------------------------------------------------------------------------------------------- Notes: Equation 1: 47.5M1/3 (1 + [DRm / 10.1])1/6 Pa-sec. Equation 2: 103M1/3 (1 + [DRm / 10.1])1/6 Pa-sec. M = mass of the animals in kg. DRm = depth of the receiver (animal) in meters. SPL = sound pressure level. Impulsive--Air Guns and Impact Pile Driving Impact pile driving produces impulsive noise; therefore, the criteria used to assess the onset of TTS and PTS are identical to those used for air guns, as well as explosives (see Table 15 above) (see Hearing Loss from air guns in Section 6.4.3.1, Methods for Analyzing Impacts from air guns in the Navy's rulemaking/LOA application). Refer to the Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) report (U.S. Department of the Navy, 2017c) for detailed information on how the criteria and thresholds were derived. Non-Impulsive--Sonar and Vibratory Pile Driving/Removal Vibratory pile removal (that will be used during the ELCAS) creates continuous non-impulsive noise at low source levels for a short duration. Therefore, the criteria used to assess the onset of TTS and PTS due to exposure to sonars (non-impulsive, see Table 14 above) are also used to assess auditory impacts to marine mammals from vibratory pile driving (see Hearing Loss from Sonar and Other Transducers in Section 6.4.2.1, Methods for Analyzing Impacts from Sonars and Other Transducers in the Navy's rulemaking/LOA application). Refer to the Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) report (U.S. Department of the Navy, 2017c) for detailed information on how the criteria and thresholds were derived. Non-auditory injury (i.e., other than PTS) and mortality from sonar and other transducers is so unlikely as to be discountable under normal conditions for the reasons explained in the Potential Effects of Specified Activities on Marine Mammals and Their Habitat [[Page 29941]] section under ``Acoustically Mediated Bubble Growth and other Pressure- related Injury'' and is therefore not considered further in this analysis. Behavioral Harassment Marine mammal responses (some of which are considered disturbances that rise to the level of a take) to sound are highly variable and context specific (affected by differences in acoustic conditions, differences between species and populations; differences in gender, age, reproductive status, or social behavior; or other prior experience of the individuals), which means that there is support for alternative approaches for estimating behavioral harassment. Although the statutory definition of Level B harassment for military readiness activities requires that the natural behavior patterns of a marine mammal be significantly altered or abandoned in order to qualify as a take, the current state of science for determining those thresholds is still evolving and indefinite. In its analysis of impacts associated with sonar acoustic sources (which was coordinated with NMFS), the Navy proposes, and NMFS supports, an updated conservative approach that likely overestimates the number of takes by Level B harassment due to behavioral disturbance and response. Many of the responses estimated using the Navy's quantitative analysis are most likely to be moderate severity (see Southall et al., 2007 for behavior response severity scale). Moderate severity responses would be considered significant if they were sustained for a duration long enough that it caused an animal to be outside of normal variation in daily behavioral patterns in feeding, reproduction, resting, migration/movement, or social cohesion. Many of the behavioral reactions predicted by the Navy's quantitative analysis are only expected to exceed an animal's behavioral threshold for a single exposure lasting several minutes. It is therefore likely that some of the exposures that are included in the estimated behavioral harassment takes would not actually constitute significant alterations or abandonment of natural behavior patterns. The Navy and NMFS have used the best available science to address the challenge of differentiating between behavioral reactions that rise to the level of a take and those that do not, but have erred on the side of caution where uncertainty exists (e.g., counting these lower duration reactions as take). This conservative choice likely results in some degree of overestimation of behavioral harassment take. Therefore, this analysis includes the maximum number of behavioral disturbances and responses that are reasonably possible to occur. Air Guns and Pile Driving Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source (e.g., frequency, predictability, duty cycle), the environment (e.g., bathymetry), and the receiving animals (hearing, motivation, experience, demography, behavioral context) and can be difficult to predict (Southall et al., 2007, Ellison et al., 2011). Based on what the available science indicates and the practical need to use a threshold based on a factor that is both predictable and measurable for most activities, NMFS uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS predicts that marine mammals are likely to be behaviorally harassed in a manner we consider Level B harassment when exposed to underwater anthropogenic noise above received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g., vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., seismic air guns) or intermittent (e.g., scientific sonar) sources. To estimate behavioral effects from air guns, the existing NMFS Level B harassment threshold of 160 dB re 1 [micro]Pa (rms) is used. The root mean square calculation for air guns is based on the duration defined by 90 percent of the cumulative energy in the impulse. The existing NMFS Level B harassment thresholds were also applied to estimate behavioral effects from impact and vibratory pile driving (Table 16). Table 16--Pile Driving Level B Thresholds Used in This Analysis To Predict Behavioral Responses From Marine Mammals ------------------------------------------------------------------------ Pile driving criteria (SPL, dB re 1 [mu]Pa) Level B disturbance threshold ------------------------------------------------------------------------- Underwater vibratory Underwater impact ------------------------------------------------------------------------ 120 dB rms................................ 160 dB rms. ------------------------------------------------------------------------ Notes: Root mean square calculation for impact pile driving is based on the duration defined by 90 percent of the cumulative energy in the impulse. Root mean square for vibratory pile driving is calculated based on a representative time series long enough to capture the variation in levels, usually on the order of a few seconds. dB: decibel; dB re 1 [micro]Pa: decibel referenced to 1 micropascal; rms: root mean square. Sonar As noted, the Navy coordinated with NMFS to propose behavioral harassment thresholds specific to their military readiness activities utilizing active sonar. Behavioral response criteria are used to estimate the number of animals that may exhibit a behavioral response to sonar and other transducers. The way the criteria were derived is discussed in detail in the Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) report (U.S. Department of the Navy, 2017c). Developing the new behavioral criteria involved multiple steps. All peer-reviewed published behavioral response studies conducted both in the field and on captive animals were examined in order to understand the breadth of behavioral responses of marine mammals to sonar and other transducers. NMFS supported the development of this methodology and considered it appropriate to calculate take and support the preliminary determinations made in the proposed rule. In the Navy acoustic impact analyses during Phase II, the likelihood of behavioral effects to sonar and other transducers was based on a probabilistic function (termed a behavioral response function--BRF), that related the likelihood (i.e., probability) of a behavioral response to the received SPL. The BRF was used to estimate the percentage of an exposed population that is likely to exhibit altered behaviors or behavioral disturbance at a given received SPL. This BRF relied on the assumption that sound poses a negligible risk to marine mammals if they are exposed to SPL below a certain ``basement'' value. Above the basement exposure SPL, the probability of a response increased with increasing SPL. Two BRFs were used in Navy acoustic impact analyses: BRF1 for mysticetes and BRF2 for other species. BRFs were not used for beaked whales during Phase II analyses. Instead, step functions at SPLs of 120 dB re 1 [mu]Pa and 140 dB re 1 [mu]Pa were used for harbor porpoises and beaked whales, respectively, as thresholds to predict behavioral disturbance. It should be noted that in the HSTT Study Area there are no harbor porpoise. Developing the new behavioral criteria for Phase III involved multiple steps: All available behavioral response studies conducted both in the field and on captive animals were examined in order to better understand the breadth of behavioral responses of marine mammals to sonar and other transducers. Marine mammal species [[Page 29942]] were placed into behavioral criteria groups based on their known or suspected behavioral sensitivities to sound. In most cases these divisions were driven by taxonomic classifications (e.g., mysticetes, pinnipeds). The data from the behavioral studies were analyzed by looking for significant responses, or lack thereof, for each experimental session. The Navy used cutoff distances beyond which the potential of significant behavioral responses (and therefore Level B harassment) is considered to be unlikely (see Table 16 below). For animals within the cutoff distance, a behavioral response function based on a received SPL as presented in Section 3.1.0 of the Navy's rulemaking/LOA application was used to predict the probability of a potential significant behavioral response. For training and testing events that contain multiple platforms or tactical sonar sources that exceed 215 dB re 1 [mu]Pa @ 1 m, this cutoff distance is substantially increased (i.e., doubled) from values derived from the literature. The use of multiple platforms and intense sound sources are factors that probably increase responsiveness in marine mammals overall. There are currently few behavioral observations under these circumstances; therefore, the Navy conservatively predicted significant behavioral responses at farther ranges as shown in Table 17, versus less intense events. Table 17--Cutoff Distances for Moderate Source Level, Single Platform Training and Testing Events and for All Other Events With Multiple Platforms or Sonar With Source Levels at or Exceeding 215 dB re 1 [micro]Pa @1 m ------------------------------------------------------------------------ Moderate SL/ single High SL/ multi- Criteria group platform platform cutoff cutoff distance (km) distance (km) ------------------------------------------------------------------------ Odontocetes............................. 10 20 Pinnipeds............................... 5 10 Mysticetes.............................. 10 20 Beaked Whales........................... 25 50 Harbor Porpoise......................... 20 40 ------------------------------------------------------------------------ Notes: dB re 1 [micro]Pa @1 m: Decibels referenced to 1 micropascal at 1 meter; km: kilometer; SL: source level. There are no harbor porpoise in the HSTT Study Area, but are included in Table 16 for consistency with other Navy Proposed Rules. Tables 18-22 show the range to received sound levels in 6-dB steps from 5 representative sonar bins and the percentage of animals that may be taken under each behavioral response function. Cells are shaded if the mean range value for the specified received level exceeds the distance cutoff range for a particular hearing group and therefore are not included in the estimated take. See Section 6.4.2.1.1 (Methods for Analyzing Impacts from Sonars and Other Transducers) of the Navy's application for further details on the derivation and use of the behavioral response functions, thresholds, and the cutoff distances, which were coordinated with NMFS. Table 18 illustrates the potentially significant behavioral response for LFAS. BILLING CODE 3510-22-P [[Page 29943]] [GRAPHIC] [TIFF OMITTED] TP26JN18.094 [[Page 29944]] Tables 19 through Table 21 illustrates the potentially significant behavioral response for MFAS. [GRAPHIC] [TIFF OMITTED] TP26JN18.095 [[Page 29945]] [GRAPHIC] [TIFF OMITTED] TP26JN18.096 [[Page 29946]] [GRAPHIC] [TIFF OMITTED] TP26JN18.097 [[Page 29947]] Table 22 illustrates the potentially significant behavioral response for HFAS. [GRAPHIC] [TIFF OMITTED] TP26JN18.098 BILLING CODE 3510-22-C [[Page 29948]] Explosives Phase III explosive criteria for behavioral thresholds for marine mammals is the hearing groups' TTS threshold minus 5 dB (see Table 23 below and Table 15 for the TTS thresholds for explosives) for events that contain multiple impulses from explosives underwater. This was the same approach as taken in Phase II for explosive analysis. See the Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) report (U.S. Department of the Navy, 2017c) for detailed information on how the criteria and thresholds were derived. Table 23--Phase III Behavioral Thresholds for Explosives for Marine Mammals ------------------------------------------------------------------------ Functional hearing SEL Medium group (weighted) ------------------------------------------------------------------------ Underwater.......................... LF 163 Underwater.......................... MF 165 Underwater.......................... HF 135 Underwater.......................... PW 165 Underwater.......................... OW 183 ------------------------------------------------------------------------ Note: Weighted SEL thresholds in dB re 1 [mu]Pa\2\s underwater. Navy's Acoustic Effects Model Sonar and Other Transducers and Explosives The Navy's Acoustic Effects Model calculates sound energy propagation from sonar and other transducers and explosives during naval activities and the sound received by animat dosimeters. Animat dosimeters are virtual representations of marine mammals distributed in the area around the modeled naval activity that each records its individual sound ``dose.'' The model bases the distribution of animats over the HSTT Study Area on the density values in the Navy Marine Species Density Database and distributes animats in the water column proportional to the known time that species spend at varying depths. The model accounts for environmental variability of sound propagation in both distance and depth when computing the received sound level received by the animats. The model conducts a statistical analysis based on multiple model runs to compute the estimated effects on animals. The number of animats that exceed the thresholds for effects is tallied to provide an estimate of the number of marine mammals that could be affected. Assumptions in the Navy model intentionally err on the side of overestimation when there are unknowns. Naval activities are modeled as though they would occur regardless of proximity to marine mammals meaning that no mitigation is considered (i.e., no power down or shut down modeled) and without any avoidance of the activity by the animal. The final step of the quantitative analysis of acoustic effects is to consider the implementation of mitigation and the possibility that marine mammals would avoid continued or repeated sound exposures. For more information on this process, see the discussion in the ``Take Requests'' subsection below. Many explosions from ordnance such as bombs and missiles actually occur upon impact with above-water targets. However, for this analysis, sources such as these were modeled as exploding underwater. This overestimates the amount of explosive and acoustic energy entering the water. The model estimates the impacts caused by individual training and testing exercises. During any individual modeled event, impacts to individual animats are considered over 24-hour periods. The animats do not represent actual animals, but rather they represent a distribution of animals based on density and abundance data, which allows for a statistical analysis of the number of instances that marine mammals may be exposed to sound levels resulting in an effect. Therefore, the model estimates the number of instances in which an effect threshold was exceeded over the course of a year, but does not estimate the number of individual marine mammals that may be impacted over a year (i.e., some marine mammals could be impacted several times, while others would not experience any impact). A detailed explanation of the Navy's Acoustic Effects Model is provided in the technical report Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing report (U.S. Department of the Navy, 2017b). Air Guns and Pile Driving The Navy's quantitative analysis estimates the sound and energy received by marine mammals distributed in the area around planned Navy activities involving air guns. The analysis for air guns was similar to explosives as an impulsive source, except explosive impulsive sources were placed into bins based on net explosive weights, while each non- explosive impulsive source (air guns) was assigned its own unique bin. The impulsive model used in the Navy's analysis used metrics to describe the sound received by the animats and the SPLrms criteria was only applied to air guns. See the technical report titled Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing report (U.S. Department of the Navy, 2017b) for additional details. Underwater noise effects from pile driving and vibratory pile extraction were modeled using actual measures of impact pile driving and vibratory removal during construction of an Elevated Causeway System (Illingworth and Rodkin, 2015, 2016). A conservative estimate of spreading loss of sound in shallow coastal waters (i.e., transmission loss = 16.5 * Log10 (radius)) was applied based on spreading loss observed in actual measurements. Inputs used in the model are provided in Section 1.4.1.3 (Pile Driving) of the Navy's rulemaking/LOA application, including source levels; the number of strikes required to drive a pile and the duration of vibratory removal per pile; the number of piles driven or removed per day; and the number of days of pile driving and removal. Range to Effects The following section provides range to effects for sonar and other active acoustic sources as well as explosives to specific acoustic thresholds determined using the Navy Acoustic Effects Model. Marine mammals exposed within these ranges for the shown duration are predicted to experience the associated effect. Range to effects is important information not only for predicting acoustic impacts, but also in verifying the accuracy of model results against real-world situations and determining adequate mitigation ranges to avoid higher level effects, especially physiological effects to marine mammals. Sonar The range to received sound levels in 6-dB steps from 5 representative sonar bins and the percentage of the total number of animals that may exhibit a significant behavioral response (and therefore Level B harassment) under each behavioral response function are shown in Table 18 through Table 22 above, respectively. See Section 6.4.2.1.1 (Impact Ranges for Sonar and Other Transducers) of the Navy's rulemaking/LOA application for additional details on the derivation and use of the behavioral response functions, thresholds, and the cutoff distances. The ranges to the PTS for five representative sonar systems for an [[Page 29949]] exposure of 30 seconds is shown in Table 24 relative to the marine mammal's functional hearing group. This period (30 seconds) was chosen based on examining the maximum amount of time a marine mammal would realistically be exposed to levels that could cause the onset of PTS based on platform (e.g., ship) speed and a nominal animal swim speed of approximately 1.5 m per second. The ranges provided in the table include the average range to PTS, as well as the range from the minimum to the maximum distance at which PTS is possible for each hearing group. Table 24--Range to Permanent Threshold Shift (meters) for Five Representative Sonar Systems ---------------------------------------------------------------------------------------------------------------- Approximate range in meters for PTS from 30 seconds exposure Functional hearing group ------------------------------------------------------------------------------- Sonar bin LF Sonar bin MF1 Sonar bin MF4 Sonar bin MF5 Sonar bin HF4 ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetacean.......... 0 (0-0) 65 (65-65) 14 (0-15) 0 (0-0) 0 (0-0) Mid-frequency Cetacean.......... 0 (0-0) 16 (16-16) 3 (3-3) 0 (0-0) 1 (0-2) High-frequency Cetacean......... 0 (0-0) 181 (180-190) 30 (30-30) 9 (8-10) 30 (8-80) Otariidae....................... 0 (0-0) 6 (6-6) 0 (0-0) 0 (0-0) 0 (0-0) Phocinae........................ 0 (0-0) 45 (45-45) 11 (11-11) 0 (0-0) 0 (0-0) ---------------------------------------------------------------------------------------------------------------- \1\ PTS ranges extend from the sonar or other active acoustic sound source to the indicated distance. The average range to PTS is provided as well as the range from the estimated minimum to the maximum range to PTS in parenthesis. The tables below illustrate the range to TTS for 1, 30, 60, and 120 seconds from 5 representative sonar systems (see Table 25 through Table 29). Table 25--Ranges to Temporary Threshold Shift for Sonar Bin LF5 Over a Representative Range of Environments Within the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Approximate TTS ranges (meters) \1\ --------------------------------------------------------------- Hearing group Sonar bin LF5M (low frequency sources <180 dB source level) --------------------------------------------------------------- 1 second 30 seconds 60 seconds 120 seconds ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetacean.......................... 3 (0-4) 3 (0-4) 3 (0-4) 3 (0-4) Mid-frequency Cetacean.......................... 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) High-frequency Cetacean......................... 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) Otariidae....................................... 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) Phocinae........................................ 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) ---------------------------------------------------------------------------------------------------------------- \1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. Table 26--Ranges to Temporary Threshold Shift for Sonar Bin MF1 Over a Representative Range of Environments Within the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Approximate TTS ranges (meters) \1\ ----------------------------------------------------------------------------------- Hearing group Sonar bin MF1 (e.g., SQS-53 ASW hull-mounted sonar) ----------------------------------------------------------------------------------- 1 second 30 seconds 60 seconds 120 seconds ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetacean...... 903 (850-1,025) 903 (850-1,025) 1,264 (1,025-2,275) 1,839 (1,275-3,025) Mid-frequency Cetacean...... 210 (210-210) 210 (210-210) 302 (300-310) 379 (370-390) High-frequency Cetacean..... 3,043 (1,525-4,775) 3,043 (1,525-4,775) 4,739 (2,025-6,275) 5,614 (2,025-7,525) Otariidae................... 65 (65-65) 65 (65-65) 106 (100-110) 137 (130-140) Phocinae.................... 669 (650-725) 669 (650-725) 970 (900-1,025) 1,075 (1,025-1,525) ---------------------------------------------------------------------------------------------------------------- \1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. [[Page 29950]] Table 27--Ranges to Temporary Threshold Shift (meters) for Sonar Bin MF4 Over a Representative Range of Environments Within the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Approximate TTS ranges (meters) \1\ ----------------------------------------------------------------------------------- Hearing group Sonar bin MF4 (e.g., AQS-22 ASW dipping sonar) ----------------------------------------------------------------------------------- 1 second 30 seconds 60 seconds 120 seconds ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetacean...... 77 (0-85) 162 (150-180) 235 (220-290) 370 (310-600) Mid-frequency Cetacean...... 22 (22-22) 35 (35-35) 49 (45-50) 70 (70-70) High-frequency Cetacean..... 240 (220-300) 492 (440-775) 668 (550-1,025) 983 (825-2,025) Otariidae................... 8 (8-8) 15 (15-15) 19 (19-19) 25 (25-25) Phocinae.................... 65 (65-65) 110 (110-110) 156 (150-170) 269 (240-460) ---------------------------------------------------------------------------------------------------------------- \1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. Table 28--Ranges to Temporary Threshold Shift (meters) for Sonar Bin MF5 Over a Representative Range of Environments Within the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Approximate TTS ranges (meters) \1\ ----------------------------------------------------------------------------------- Hearing group Sonar bin MF5 (e.g., SSQ-62 ASW sonobuoy) ----------------------------------------------------------------------------------- 1 second 30 seconds 60 seconds 120 seconds ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetacean...... 10 (0-12) 10 (0-12) 14 (0-18) 21 (0-25) Mid-frequency Cetacean...... 6 (0-9) 6 (0-9) 12 (0-13) 17 (0-21) High-frequency Cetacean..... 118 (100-170) 118 (100-170) 179 (150-480) 273 (210-700) Otariidae................... 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) Phocinae.................... 9 (8-10) 9 (8-10) 14 (14-16) 21 (21-25) ---------------------------------------------------------------------------------------------------------------- \1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. Table 29--Ranges to Temporary Threshold Shift (meters) for Sonar Bin HF4 Over a Representative Range of Environments Within the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Approximate TTS ranges (meters) \1\ ----------------------------------------------------------------------------------- Hearing group Sonar bin HF4 (e.g., SQS-20 mine hunting sonar) ----------------------------------------------------------------------------------- 1 second 30 seconds 60 seconds 120 seconds ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetacean...... 1 (0-3) 2 (0-5) 4 (0-7) 6 (0-11) Mid-frequency Cetacean...... 10 (4-17) 17 (6-35) 24 (7-60) 34 (9-90) High-frequency Cetacean..... 168 (25-550) 280 (55-775) 371 (80-1,275) 470 (100-1,525) Otariidae................... 0 (0-0) 0 (0-0) 0 (0-0) 1 (0-1) Phocinae.................... 2 (0-5) 5 (2-8) 8 (3-13) 11 (4-22) ---------------------------------------------------------------------------------------------------------------- \1\ Ranges to TTS represent the model predictions in different areas and seasons within the Study Area. The zone in which animals are expected to suffer TTS extend from onset-PTS to the distance indicated. The average range to TTS is provided as well as the range from the estimated minimum to the maximum range to TTS in parentheses. Explosives The following section provides the range (distance) over which specific physiological or behavioral effects are expected to occur based on the explosive criteria (see Chapter 6.5.2.1.1 of the Navy's rulemaking/LOA application and the Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) report (U.S. Department of the Navy, 2017c) and the explosive propagation calculations from the Navy Acoustic Effects Model (see Chapter 6.5.2.1.3, Navy Acoustic Effects Model of the Navy's rulemaking/LOA application). The range to effects are shown for a range of explosive bins, from E1 (up to 0.25 lb net explosive weight) to E12 (up to 1,000 lb net explosive weight) (Tables 30 through 35). Ranges are determined by modeling the distance that noise from an explosion will need to propagate to reach exposure level thresholds specific to a hearing group that will cause behavioral response (to the degree of a take), TTS, PTS, and non-auditory injury. Ranges are provided for a representative source depth and cluster size for each bin. For events with multiple explosions, sound from successive explosions can be expected to accumulate and increase the range to the onset of an impact based on SEL thresholds. Range to effects is important information in not only [[Page 29951]] predicting impacts from explosives, but also in verifying the accuracy of model results against real-world situations and determining adequate mitigation ranges to avoid higher level effects, especially physiological effects to marine mammals. For additional information on how ranges to impacts from explosions were estimated, see the technical report Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing (U.S. Navy, 2017b). Table 30 shows the minimum, average, and maximum ranges to onset of auditory and behavioral effects for high-frequency cetaceans based on the developed thresholds. Table 30--SEL-Based Ranges (meters) to Onset PTS, Onset TTS, and Behavioral Reaction for High-Frequency Cetaceans -------------------------------------------------------------------------------------------------------------------------------------------------------- Range to effects for explosives: high frequency cetacean \1\ --------------------------------------------------------------------------------------------------------------------------------------------------------- Source depth Bin (m) Cluster size PTS TTS Behavioral -------------------------------------------------------------------------------------------------------------------------------------------------------- E1........................................ 0.1 1 353 (130-825) 1,234 (290-3,025) 2,141 (340-4,775) 25 1,188 (280-3,025) 3,752 (490-8,525) 5,196 (675-12,275) E2........................................ 0.1 1 425 (140-1,275) 1,456 (300-3,525) 2,563 (390-5,275) 10 988 (280-2,275) 3,335 (480-7,025) 4,693 (650-10,275) E3........................................ 0.1 1 654 (220-1,525) 2,294 (350-4,775) 3,483 (490-7,775) 12 1,581 (300-3,525) 4,573 (650-10,275) 6,188 (725-14,775) 18.25 1 747 (550-1,525) 3,103 (950-6,025) 5,641 (1,000-9,275) 12 1,809 (875-4,025) 7,807 (1,025-12,775) 10,798 (1,025-17,775) E4........................................ 3 2 2,020 (1,025-3,275) 3,075 (1,025-6,775) 3,339 (1,025-9,775) 15.25 2 970 (600-1,525) 4,457 (1,025-8,525) 6,087 (1,275-12,025) 19.8 2 1,023 (1,000-1,025) 4,649 (2,275-8,525) 6,546 (3,025-11,025) 198 2 959 (875-1,525) 4,386 (3,025-7,525) 5,522 (3,025-9,275) E5........................................ 0.1 25 2,892 (440-6,275) 6,633 (725-16,025) 8,925 (800-22,775) 15.25 25 4,448 (1,025-7,775) 10,504 (1,525-18,275) 13,605 (1,775-24,775) E6........................................ 0.1 1 1,017 (280-2,525) 3,550 (490-7,775) 4,908 (675-12,275) 3 1 2,275 (2,025-2,525) 6,025 (4,525-7,275) 7,838 (6,275-9,775) 15.25 1 1,238 (625-2,775) 5,613 (1,025-10,525) 7,954 (1,275-14,275) E7........................................ 3 1 3,150 (2,525-3,525) 7,171 (5,525-8,775) 8,734 (7,275-10,525) 18.25 1 2,082 (925-3,525) 6,170 (1,275-10,525) 8,464 (1,525-16,525) E8........................................ 0.1 1 1,646 (775-2,525) 4,322 (1,525-9,775) 5,710 (1,525-14,275) 45.75 1 1,908 (1,025-4,775) 5,564 (1,525-12,525) 7,197 (1,525-18,775) E9........................................ 0.1 1 2,105 (850-4,025) 4,901 (1,525-12,525) 6,700 (1,525-16,775) E10....................................... 0.1 1 2,629 (875-5,275) 5,905 (1,525-13,775) 7,996 (1,525-20,025) E11....................................... 18.5 1 3,034 (1,025-6,025) 7,636 (1,525-16,525) 9,772 (1,775-21,525) 45.75 1 2,925 (1,525-6,025) 7,152 (2,275-18,525) 9,011 (2,525-24,525) E12....................................... 0.1 1 2,868 (975-5,525) 6,097 (2,275-14,775) 8,355 (4,275-21,275) 3 3,762 (1,525-8,275) 7,873 (3,775-20,525) 10,838 (4,275-26,525) -------------------------------------------------------------------------------------------------------------------------------------------------------- \1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. Table 31 shows the minimum, average, and maximum ranges to onset of auditory and behavioral effects for mid-frequency cetaceans based on the developed thresholds. Table 31--SEL-Based Ranges (meters) to Onset PTS, Onset TTS, and Behavioral Reaction for Mid-Frequency Cetaceans -------------------------------------------------------------------------------------------------------------------------------------------------------- Range to effects for explosives: mid-frequency cetacean 1 --------------------------------------------------------------------------------------------------------------------------------------------------------- Source depth Bin (m) Cluster size PTS TTS Behavioral -------------------------------------------------------------------------------------------------------------------------------------------------------- E1................................................. 0.1 1 25 (25-25) 118 (80-210) 178 (100-320) 25 107 (75-170) 476 (150-1,275) 676 (240-1,525) E2................................................. 0.1 1 30 (30-35) 145 (95-240) 218 (110-400) 10 88 (65-130) 392 (140-825) 567 (190-1,275) E3................................................. 0.1 1 50 (45-65) 233 (110-430) 345 (130-600) 12 153 (90-250) 642 (220-1,525) 897 (270-2,025) 18.25 1 38 (35-40) 217 (190-900) 331 (290-850) 12 131 (120-250) 754 (550-1,525) 1,055 (600-2,525) E4................................................. 3 2 139 (110-160) 1,069 (525-1,525) 1,450 (875-1,775) 15.25 2 71 (70-75) 461 (400-725) 613 (470-750) 19.8 2 69 (65-70) 353 (350-360) 621 (600-650) 198 2 49 (0-55) 275 (270-280) 434 (430-440) E5................................................. 0.1 25 318 (130-625) 1,138 (280-3,025) 1,556 (310-3,775) 15.25 25 312 (290-725) 1,321 (675-2,525) 1,980 (850-4,275) [[Page 29952]] E6................................................. 0.1 1 98 (70-170) 428 (150-800) 615 (210-1,525) 3 1 159 (150-160) 754 (650-850) 1,025 (1,025-1,025) 15.25 1 88 (75-180) 526 (450-875) 719 (500-1,025) E7................................................. 3 1 240 (230-260) 1,025 (1,025-1,025) 1,900 (1,775-2,275) 18.25 1 166 (120-310) 853 (500-1,525) 1,154 (550-1,775) E8................................................. 0.1 1 160 (150-170) 676 (500-725) 942 (600-1,025) 45.75 1 128 (120-170) 704 (575-2,025) 1,040 (750-2,525) E9................................................. 0.1 1 215 (200-220) 861 (575-950) 1,147 (650-1,525) E10................................................ 0.1 1 275 (250-480) 1,015 (525-2,275) 1,424 (675-3,275) E11................................................ 18.5 1 335 (260-500) 1,153 (650-1,775) 1,692 (775-3,275) 45.75 1 272 (230-825) 1,179 (825-3,025) 1,784 (1,000-4,275) E12................................................ 0.1 1 334 (310-350) 1,151 (700-1,275) 1,541 (800-3,525) 0.1 3 520 (450-550) 1,664 (800-3,525) 2,195 (925-4,775) -------------------------------------------------------------------------------------------------------------------------------------------------------- 1 Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. Table 32 shows the minimum, average, and maximum ranges to onset of auditory and behavioral effects for low-frequency cetaceans based on the developed thresholds. Table 32--SEL-Based Ranges (meters) to Onset PTS, Onset TTS, and Behavioral Reaction for Low-Frequency Cetaceans -------------------------------------------------------------------------------------------------------------------------------------------------------- Range to effects for explosives: low frequency cetacean 1 --------------------------------------------------------------------------------------------------------------------------------------------------------- Source depth Bin (m) Cluster size PTS TTS Behavioral -------------------------------------------------------------------------------------------------------------------------------------------------------- E1................................................. 0.1 1 51 (40-70) 227 (100-320) 124 (70-160) 25 205 (95-270) 772 (270-1,275) 476 (190-725) E2................................................. 0.1 1 65 (45-95) 287 (120-400) 159 (80-210) 10 176 (85-240) 696 (240-1,275) 419 (160-625) E3................................................. 0.1 1 109 (65-150) 503 (190-1,000) 284 (120-430) 12 338 (130-525) 1,122 (320-7,775) 761 (240-6,025) 18.25 1 205 (170-340) 996 (410-2,275) 539 (330-1,275) 12 651 (340-1,275) 3,503 (600-8,275) 1,529 (470-3,275) E4................................................. 3 2 493 (440-1,000) 2,611 (1,025-4,025) 1,865 (950-2,775) 15.25 2 583 (350-850) 3,115 (1,275-5,775) 1,554 (1,000-2,775) 19.8 2 378 (370-380) 1,568 (1,275-1,775) 926 (825-950) 198 2 299 (290-300) 2,661 (1,275-3,775) 934 (900-950) E5................................................. 0.1 25 740 (220-6,025) 2,731 (460-22,275) 1,414 (350-14,275) 15.25 25 1,978 (1,025-5,275) 8,188 (3,025-19,775) 4,727 (1,775-11,525) E6................................................. 0.1 1 250 (100-420) 963 (260-7,275) 617 (200-1,275) 3 1 711 (525-825) 3,698 (1,525-4,275) 2,049 (1,025-2,525) 15.25 1 718 (390-2,025) 3,248 (1,275-8,525) 1,806 (950-4,525) E7................................................. 3 1 1,121 (850-1,275) 5,293 (2,025-6,025) 3,305 (1,275-4,025) 18.25 1 1,889 (1,025-2,775) 6,157 (2,775-11,275) 4,103 (2,275-7,275) E8................................................. 0.1 1 460 (170-950) 1,146 (380-7,025) 873 (280-3,025) 45.75 1 1,049 (550-2,775) 4,100 (1,025-14,275) 2,333 (800-7,025) E9................................................. 0.1 1 616 (200-1,275) 1,560 (450-12,025) 1,014 (330-5,025) E10................................................ 0.1 1 787 (210-2,525) 2,608 (440-18,275) 1,330 (330-9,025) E11................................................ 18.5 1 4,315 (2,025-8,025) 10,667 (4,775-26,775) 7,926 (3,275-21,025) 45.75 1 1,969 (775-5,025) 9,221 (2,525-29,025) 4,594 (1,275-16,025) E12................................................ 0.1 1 815 (250-3,025) 2,676 (775-18,025) 1,383 (410-8,525) 0.1 3 1,040 (330-6,025) 4,657 (1,275-31,275) 2,377 (700-16,275) -------------------------------------------------------------------------------------------------------------------------------------------------------- 1 Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. Table 33 shows the minimum, average, and maximum ranges to onset of auditory and behavioral effects for phocids based on the developed thresholds. [[Page 29953]] Table 33--SEL-Based Ranges (meters) to Onset PTS, Onset TTS, and Behavioral Reaction for Phocids -------------------------------------------------------------------------------------------------------------------------------------------------------- Range to effects for explosives: phocids 1 --------------------------------------------------------------------------------------------------------------------------------------------------------- Source depth Bin (m) Cluster size PTS TTS Behavioral -------------------------------------------------------------------------------------------------------------------------------------------------------- E1................................................. 0.1 1 45 (40-65) 210 (100-290) 312 (130-430) 25 190 (95-260) 798 (280-1,275) 1,050 (360-2,275) E2................................................. 0.1 1 58 (45-75) 258 (110-360) 383 (150-550) 10 157 (85-240) 672 (240-1,275) 934 (310-1,525) E3................................................. 0.1 1 96 (60-120) 419 (160-625) 607 (220-900) 12 277 (120-390) 1,040 (370-2,025) 1,509 (525-6,275) 18.25 1 118 (110-130) 621 (500-1,275) 948 (700-2,025) 12 406 (330-875) 1,756 (1,025-4,775) 3,302 (1,025-6,275) E4................................................. 3 2 405 (300-430) 1,761 (1,025-2,775) 2,179 (1,025-3,275) 15.25 2 265 (220-430) 1,225 (975-1,775) 1,870 (1,025-3,275) 19.8 2 220 (220-220) 991 (950-1,025) 1,417 (1,275-1,525) 198 2 150 (150-150) 973 (925-1,025) 2,636 (2,025-3,525) E5................................................. 0.1 25 569 (200-850) 2,104 (725-9,275) 2,895 (825-11,025) 15.25 25 920 (825-1,525) 5,250 (2,025-10,275) 7,336 (2,275-16,025) E6................................................. 0.1 1 182 (90-250) 767 (270-1,275) 1,011 (370-1,775) 3 1 392 (340-440) 1,567 (1,275-1,775) 2,192 (2,025-2,275) 15.25 1 288 (250-600) 1,302 (1,025-3,275) 2,169 (1,275-5,775) E7................................................. 3 1 538 (450-625) 2,109 (1,775-2,275) 2,859 (2,775-3,275) 18.25 1 530 (460-750) 2,617 (1,025-4,525) 3,692 (1,525-5,275) E8................................................. 0.1 1 311 (290-330) 1,154 (625-1,275) 1,548 (725-2,275) 45.75 1 488 (380-975) 2,273 (1,275-5,275) 3,181 (1,525-8,025) E9................................................. 0.1 1 416 (350-470) 1,443 (675-2,025) 1,911 (800-3,525) E10................................................ 0.1 1 507 (340-675) 1,734 (725-3,525) 2,412 (800-5,025) E11................................................ 18.5 1 1,029 (775-1,275) 5,044 (2,025-8,775) 6,603 (2,525-14,525) 45.75 1 881 (700-2,275) 3,726 (2,025-8,775) 5,082 (2,025-13,775) E12................................................ 0.1 1 631 (450-750) 1,927 (800-4,025) 2,514 (925-5,525) 0.1 3 971 (550-1,025) 2,668 (1,025-6,275) 3,541 (1,775-9,775) -------------------------------------------------------------------------------------------------------------------------------------------------------- \1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. Table 34 shows the minimum, average, and maximum ranges to onset of auditory and behavioral effects for ottariids based on the developed thresholds. Table 34--SEL-Based Ranges (meters) to Onset PTS, Onset TTS, and Behavioral Reaction for Otariids -------------------------------------------------------------------------------------------------------------------------------------------------------- Range to effects for explosives: otariids 1 range to effects for explosives: mid-frequency cetacean --------------------------------------------------------------------------------------------------------------------------------------------------------- Source depth Bin (m) Cluster size PTS TTS Behavioral -------------------------------------------------------------------------------------------------------------------------------------------------------- E1................................................. 0.1 1 7 (7-7) 34 (30-40) 56 (45-70) 25 30 (25-35) 136 (80-180) 225 (100-320) E2................................................. 0.1 1 9 (9-9) 41 (35-55) 70 (50-95) 10 25 (25-30) 115 (70-150) 189 (95-250) E3................................................. 0.1 1 16 (15-19) 70 (50-95) 115 (70-150) 12 45 (35-65) 206 (100-290) 333 (130-450) 18.25 1 15 (15-15) 95 (90-100) 168 (150-310) 12 55 (50-60) 333 (280-750) 544 (440-1,025) E4................................................. 3 2 64 (40-85) 325 (240-340) 466 (370-490) 15.25 2 30 (30-35) 205 (170-300) 376 (310-575) 19.8 2 25 (25-25) 170 (170-170) 290 (290-290) 198 2 17 (0-25) 117 (110-120) 210 (210-210) E5................................................. 0.1 25 98 (60-120) 418 (160-575) 626 (240-1,000) 15.25 25 151 (140-260) 750 (650-1,025) 1,156 (975-2,025) E6................................................. 0.1 1 30 (25-35) 134 (75-180) 220 (100-320) 3 1 53 (50-55) 314 (280-390) 459 (420-525) 15.25 1 36 (35-40) 219 (200-380) 387 (340-625) E7................................................. 3 1 93 (90-100) 433 (380-500) 642 (550-800) 18.25 1 73 (70-75) 437 (360-525) 697 (600-850) E8................................................. 0.1 1 50 (50-50) 235 (220-250) 385 (330-450) 45.75 1 55 (55-60) 412 (310-775) 701 (500-1,525) E9................................................. 0.1 1 68 (65-70) 316 (280-360) 494 (390-625) E10................................................ 0.1 1 86 (80-95) 385 (240-460) 582 (390-800) E11................................................ 18.5 1 158 (150-200) 862 (750-975) 1,431 (1,025-2,025) 45.75 1 117 (110-130) 756 (575-1,525) 1,287 (950-2,775) E12................................................ 0.1 1 104 (100-110) 473 (370-575) 709 (480-1,025) [[Page 29954]] 0.1 3 172 (170-180) 694 (480-1,025) 924 (575-1,275) -------------------------------------------------------------------------------------------------------------------------------------------------------- 1 Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. Values depict the range produced by SEL hearing threshold criteria levels. E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. Table 35 which show the minimum, average, and maximum ranges due to varying propagation conditions to non-auditory injury as a function of animal mass and explosive bin (i.e., net explosive weight). These ranges represent the larger of the range to slight lung injury or gastrointestinal tract injury for representative animal masses ranging from 10 to 72,000 kg and different explosive bins ranging from 0.25 to 1,000 lb net explosive weight. Animals within these water volumes would be expected to receive minor injuries at the outer ranges, increasing to more substantial injuries, and finally mortality as an animal approaches the detonation point. Table 35--Ranges \1\ to 50 Percent Non-Auditory Injury Risk for All Marine Mammal Hearing Groups as a Function of Animal Mass [10-72,000 kg] ------------------------------------------------------------------------ Range (m) (min- Bin max) ------------------------------------------------------------------------ E1.................................................... 12 (11-13) E2.................................................... 15 (15-20) E3.................................................... 25 (25-30) E4.................................................... 32 (0-75) E5.................................................... 40 (35-140) E6.................................................... 52 (40-120) E7.................................................... 145 (100-500) E8.................................................... 117 (75-400) E9.................................................... 120 (90-290) E10................................................... 174 (100-480) E11................................................... 443 (350-1,775) E12................................................... 232 (110-775) ------------------------------------------------------------------------ Note: \1\ Average distance (m) to mortality is depicted above the minimum and maximum distances which are in parentheses. E13 not modeled due to surf zone use and lack of marine mammal receptors at site- specific location. Differences between bins E11 and E12 due to different ordnance types and differences in model parameters. Ranges to mortality, based on animal mass, are show in Table 36 below. Table 36--Ranges 1 to 50 Percent Mortality Risk for All Marine Mammal Hearing Groups as a Function of Animal Mass -------------------------------------------------------------------------------------------------------------------------------------------------------- Animal mass intervals (kg) 1 Bin ----------------------------------------------------------------------------------------------- 10 250 1,000 5,000 25,000 72,000 -------------------------------------------------------------------------------------------------------------------------------------------------------- E1...................................................... 3 (2-3) 0 (0-3) 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) E2...................................................... 4 (3-5) 1 (0-4) 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) E3...................................................... 8 (6-10) 4 (2-8) 1 (0-2) 0 (0-0) 0 (0-0) 0 (0-0) E4...................................................... 15 (0-35) 9 (0-30) 4 (0-8) 2 (0-6) 0 (0-3) 0 (0-2) E5...................................................... 13 (11-45) 7 (4-35) 3 (3-12) 2 (0-8) 0 (0-2) 0 (0-2) E6...................................................... 18 (14-55) 10 (5-45) 5 (3-15) 3 (2-10) 0 (0-3) 0 (0-2) E7...................................................... 67 (55-180) 35 (18-140) 16 (12-30) 10 (8-20) 5 (4-9) 4 (3-7) E8...................................................... 50 (24-110) 27 (9-55) 13 (0-20) 9 (4-13) 4 (0-6) 3 (0-5) E9...................................................... 32 (30-35) 20 (13-30) 10 (8-12) 7 (6-9) 4 (3-4) 3 (2-3) E10..................................................... 56 (40-190) 25 (16-130) 13 (11-16) 9 (7-11) 5 (4-5) 4 (3-4) E11..................................................... 211 (180-500) 109 (60-330) 47 (40-100) 30 (25-65) 15 (0-25) 13 (11-22) E12..................................................... 94 (50-300) 35 (20-230) 16 (13-19) 11 (9-13) 6 (5-8) 5 (4-8) -------------------------------------------------------------------------------------------------------------------------------------------------------- Note: \1\ Average distance (m) to mortality is depicted above the minimum and maximum distances which are in parentheses. E13 not modeled due to surf zone use and lack of marine mammal receptors at site-specific location. Differences between bins E11 and E12 due to different ordnance types and differences in model parameters (see Table 6-42 for details). Air Guns Table 37 and Table 38 present the approximate ranges in meters to PTS, TTS, and potential behavioral reactions for air guns for 1 and 10 pulses, respectively. Ranges are specific to the HSTT Study Area and also to each marine mammal hearing group, dependent upon their criteria and the specific locations where animals from the hearing groups and the air gun activities could overlap. Small air guns (12-60 in\3\) would be used during testing activities in the offshore areas of the Southern California Range Complex and in the Hawaii Range Complex. Generated impulses would have short durations, typically a few hundred milliseconds, with dominant frequencies below 1 kHz. The SPL and SPL peak (at a distance 1 m from the air gun) would be approximately 215 dB re 1 [micro]Pa and 227 dB re 1 [micro]Pa, respectively, if operated at the full capacity of 60 in\3\. The size of the air gun chamber can be adjusted, which would result in lower SPLs and SEL per shot. Single, small air guns lack the peak pressures that could cause non-auditory injury (see Finneran [[Page 29955]] et al., (2015)); therefore, potential impacts could include PTS, TTS, and behavioral reactions. Table 37--Range to Effects (meters) From Air Guns for 1 Pulse ---------------------------------------------------------------------------------------------------------------- Range to effects for air guns \1\ for 1 pulse (m) ----------------------------------------------------------------------------------------------------------------- Hearing group PTS (SEL) PTS (peak SPL) TTS (SEL) TTS (peak SPL) Behavioral \2\ ---------------------------------------------------------------------------------------------------------------- High-Frequency Cetacean....... 0 (0-0) 18 (15-25) 1 (0-2) 33 (25-80) 702 (290-1,525) Low-Frequency Cetacean........ 3 (3-4) 2 (2-3) 27 (23-35) 5 (4-7) 651 (200-1,525) Mid-Frequency Cetacean........ 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) 689 (290-1,525) Otariidae..................... 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) 590 (290-1,525) Phocids....................... 0 (0-0) 2 (2-3) 0 (0-0) 5 (4-8) 668 (290-1,525) ---------------------------------------------------------------------------------------------------------------- \1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. PTS and TTS values depict the range produced by SEL and Peak SPL (as noted) hearing threshold criteria levels. \2\ Behavioral values depict the ranges produced by RMS hearing threshold criteria levels. Table 38--Range to Effects (meters) From Air Guns for 10 Pulses ---------------------------------------------------------------------------------------------------------------- Range to effects for air guns \1\ for 10 pulses (m) ----------------------------------------------------------------------------------------------------------------- Hearing group PTS (SEL) PTS (Peak SPL) TTS (SEL) TTS (Peak SPL) Behavioral \2\ ---------------------------------------------------------------------------------------------------------------- High-Frequency Cetacean....... 0 (0-0) 18 (15-25) 3 (0-9) 33 (25-80) 702 (290-1,525) Low-Frequency Cetacean........ 15 (12-20) 2 (2-3) 86 (70-140) 5 (4-7) 651 (200-1,525) Mid-Frequency Cetacean........ 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) 689 (290-1,525) Otariidae..................... 0 (0-0) 0 (0-0) 0 (0-0) 0 (0-0) 590 (290-1,525) Phocids....................... 0 (0-0) 2 (2-3) 4 (3-5) 5 (4-8) 668 (290-1,525) ---------------------------------------------------------------------------------------------------------------- \1\ Average distance (m) to PTS, TTS, and behavioral thresholds are depicted above the minimum and maximum distances which are in parentheses. PTS and TTS values depict the range produced by SEL and Peak SPL (as noted) hearing threshold criteria levels. \2\ Behavioral values depict the ranges produced by RMS hearing threshold criteria levels. Pile Driving Table 39 and Table 40 present the approximate ranges in meters to PTS, TTS, and potential behavioral reactions for impact pile driving and vibratory pile removal, respectively. Non-auditory injury is not predicted for pile driving activities. Table 39--Average Ranges to Effects (meters) From Impact Pile Driving ---------------------------------------------------------------------------------------------------------------- Hearing group PTS (m) TTS (m) Behavioral (m) ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetaceans......................................... 65 529 870 Mid-frequency Cetaceans......................................... 2 16 870 High-frequency Cetaceans........................................ 65 529 870 Phocids......................................................... 19 151 870 Otariids........................................................ 2 12 870 ---------------------------------------------------------------------------------------------------------------- Note: PTS: Permanent threshold shift; TTS: Temporary threshold shift. Table 40--Average Ranges to Effect (meters) From Vibratory Pile Extraction ---------------------------------------------------------------------------------------------------------------- Hearing group PTS (m) TTS (m) Behavioral (m) ---------------------------------------------------------------------------------------------------------------- Low-frequency Cetaceans......................................... 0 3 376 Mid-frequency Cetaceans......................................... 0 4 376 High-frequency Cetaceans........................................ 7 116 376 Phocids......................................................... 0 2 376 Otariids........................................................ 0 0 376 ---------------------------------------------------------------------------------------------------------------- Note: PTS: Permanent threshold shift; TTS: Temporary threshold shift. Serious Injury or Mortality From Ship Strikes There have been two recorded Navy vessel strikes of marine mammals (two fin whales off San Diego, CA in 2009) in the HSTT Study Area from 2009 through 2017 (nine years), the period in which Navy began implementing effective mitigation measures to reduce the likelihood of vessel strikes. From unpublished NMFS data, the most commonly struck whales in Hawaii are humpback whales, and the most commonly struck whales in California are gray whales, fin whales, and humpback whales. The majority of these strikes are from non-Navy commercial shipping. For both areas (Hawaii and California), the higher strike rates to these species is largely attributed to [[Page 29956]] higher species abundance in these areas. Prior to 2009, the Navy had struck multiple species of whales off California or Hawaii, but also individuals that were not identified to species. Further, because the overall number of Navy strikes is small, it is appropriate to consider the larger record of known ship strikes (by other types of vessels) in predicting what species may potentially be involved in a Navy ship strike. Based on this information, and as described in more detail in Navy's rulemaking/LOA application and below, the Navy proposes, and NMFS preliminary agrees, to three ship strike takes to select large whale species and stocks over the five years of the authorization, with no more than two takes to several specific stocks with a higher likelihood of being struck and no more than one take of other specific stocks with a lesser likelihood of being struck (described in detail below in the Vessel Strike section). Marine Mammal Density A quantitative analysis of impacts on a species requires data on their abundance and distribution that may be affected by anthropogenic activities in the potentially impacted area. The most appropriate metric for this type of analysis is density, which is the number of animals present per unit area. Marine species density estimation requires a significant amount of effort to both collect and analyze data to produce a reasonable estimate. Unlike surveys for terrestrial wildlife, many marine species spend much of their time submerged, and are not easily observed. In order to collect enough sighting data to make reasonable density estimates, multiple observations are required, often in areas that are not easily accessible (e.g., far offshore). Ideally, marine mammal species sighting data would be collected for the specific area and time period (e.g., season) of interest and density estimates derived accordingly. However, in many places, poor weather conditions and high sea states prohibit the completion of comprehensive visual surveys. For most cetacean species, abundance within U.S. waters is estimated using line-transect surveys or mark-recapture studies (e.g., Barlow, 2010, Barlow and Forney, 2007, Calambokidis et al., 2008). The result provides one single density estimate value for each species across a broad geographic area. This is the general approach applied in estimating cetacean abundance in the NMFS SARS. Although the single value provides a good average estimate of abundance (total number of individuals) for a specified area, it does not provide information on the species distribution or concentrations within that area, and it does not estimate density for other timeframes, areas, or seasons that were not surveyed. More recently, habitat modeling has been used to estimate cetacean densities (e.g., Barlow et al., 2009; Becker et al., 2010; 2012a; 2014; Becker et al., 2016; Ferguson et al., 2006; Forney et al., 2012; 2015; Redfern et al., 2006). These models estimate cetacean density as a continuous function of habitat variables (e.g., sea surface temperature, seafloor depth, etc.) and thus allow predictions of cetacean densities on finer spatial scales than traditional line-transect or mark recapture analyses and for areas that have not been surveyed. Within the geographic area that was modeled, densities can be predicted wherever these habitat variables can be measured or estimated. To characterize the marine species density for large areas such as the Study Area, the Navy compiled data from several sources. The Navy developed a protocol to select the best available data sources based on species, area, and time (season). The resulting Geographic Information System database called the Navy Marine Species Density Database includes seasonal density values for every marine mammal species present within the HSTT Study Area. This database is described in the technical report titled U.S. Navy Marine Species Density Database Phase III for the Hawaii-Southern California Training and Testing Study Area (U.S. Department of the Navy, 2017e), hereafter referred to as the Density Technical Report. A variety of density data and density models are needed in order to develop a density database that encompasses the entirety of the HSTT Study Area. Because this data is collected using different methods with varying amounts of accuracy and uncertainty, the Navy has developed a model hierarchy to ensure the most accurate data is used when available. The Density Technical Report describes these models in detail and provides detailed explanations of the models applied to each species density estimate. The below list describes models in order of preference. 1. Spatial density models are preferred and used when available because they provide an estimate with the least amount of uncertainty by deriving estimates for divided segments of the sampling area. These models (see Becker et al., 2016; Forney et al., 2015) predict spatial variability of animal presence as a function of habitat variables (e.g., sea surface temperature, seafloor depth, etc.). This model is developed for areas, species, and, when available, specific timeframes (months or seasons) with sufficient survey data. 2. Stratified designed-based density estimates use line-transect survey data with the sampling area divided (stratified) into sub- regions, and a density is predicted for each sub-region (see Barlow, 2016; Becker et al., 2016; Bradford et al., 2017; Campbell et al., 2014; Jefferson et al., 2014). While geographically stratified density estimates provide a better indication of a species' distribution within the study area, the uncertainty is typically high because each sub- region estimate is based on a smaller stratified segment of the overall survey effort. 3. Design-based density estimations use line-transect survey data from land and aerial surveys designed to cover a specific geographic area (see Carretta et al., 2015). These estimates use the same survey data as stratified design-based estimates, but are not segmented into sub-regions and instead provide one estimate for a large surveyed area. Although relative environmental suitability (RES) models provide estimates for areas of the oceans that have not been surveyed using information on species occurrence and inferred habitat associations and have been used in past density databases, these models were not used in the current quantitative analysis. In the HSTT analysis, due to the availability of other density methods along the hierarchy the use of RES model was not necessary. When interpreting the results of the quantitative analysis, as described in the Density Technical Report, ``it is important to consider that even the best estimate of marine species density is really a model representation of the values of concentration where these animals might occur. Each model is limited to the variables and assumptions considered by the original data source provider. No mathematical model representation of any biological population is perfect, and with regards to marine mammal biodiversity, any single model method will not completely explain the actual distribution and abundance of marine mammal species. It is expected that there would be anomalies in the results that need to be evaluated, with independent information for each case, to support if we might accept or reject a model or portions of the model (U.S. Department of the Navy, 2017a).'' The Navy's estimate of abundance (based on the density estimates used) in the HSTT Study Area may differ from population abundances estimated in the NMFS's SARS for a variety of reasons. [[Page 29957]] Mainly because the Pacific SAR overlaps only 35 percent of the Hawaii part of HSTT and only about 14 percent of SOCAL. The Alaska SAR covering humpbacks present in Hawaii is another complicating factor. For some species, the stock assessment for a given species may exceed the Navy's density prediction because those species' home range extends beyond the Study Area boundaries. For other species, the stock assessment abundance may be much less than the number of animals in the Navy's modeling given the HSTT Study Area extends well beyond the U.S waters covered by the SAR abundance estimate. The primary source of density estimates are geographically specific survey data and either peer-reviewed line-transect estimates or habitat-based density models that have been extensively validated to provide the most accurate estimates possible. These factors and others described in the Density Technical Report should be considered when examining the estimated impact numbers in comparison to current population abundance information for any given species or stock. For a detailed description of the density and assumptions made for each species, see the Density Technical Report. NMFS coordinated with the Navy in the development of its take estimates and concurs that the Navy's proposed approach for density appropriately utilizes the best available science. Later, in the Negligible Impact Determination Section, we assess how the estimated take numbers compare to stock abundance in order to better understand the potential number of individuals impacted--and the rationale for which abundance estimate is used is included there. Take Requests The HSTT DEIS/OEIS considered all training and testing activities proposed to occur in the HSTT Study Area that have the potential to result in the MMPA defined take of marine mammals. The Navy determined that the following three stressors could result in the incidental taking of marine mammals. NMFS has reviewed the Navy's data and analysis and determined that it is complete and accurate and agrees that the following stressors have the potential to result in takes of marine mammals from the Specified Activities.Acoustics (sonar and other transducers; air guns; pile driving/extraction). Explosives (explosive shock wave and sound (assumed to encompass the risk due to fragmentation). Physical Disturbance and Strike (vessel strike). Acoustic and explosive sources have the potential to result in incidental takes of marine mammals by harassment, injury, or mortality. Vessel strikes have the potential to result in incidental take from injury, serious injury and/or mortality. The quantitative analysis process used for the HSTT DEIS/OEIS and the Navy's request in the rulemaking/LOA application to estimate potential exposures to marine mammals resulting from acoustic and explosive stressors is detailed in the technical report titled Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing report (U.S. Department of the Navy, 2017b). The Navy Acoustic Effects Model estimates acoustic and explosive effects without taking mitigation into account; therefore, the model overestimates predicted impacts on marine mammals within mitigation zones. To account for mitigation for marine species in the take estimates, the Navy conducts a quantitative assessment of mitigation. The Navy conservatively quantifies the manner in which mitigation is expected to reduce model-estimated PTS to TTS for exposures to sonar and other transducers, and reduce model- estimated mortality to injury for exposures to explosives. The Navy assessed the effectiveness of its mitigation measures on a per-scenario basis for four factors: (1) Species sightability, (2) a Lookout's ability to observe the range to PTS (for sonar and other transducers) and range to mortality (for explosives), (3) the portion of time when mitigation could potentially be conducted during periods of reduced daytime visibility (to include inclement weather and high sea-state) and the portion of time when mitigation could potentially be conducted at night, and (4) the ability for sound sources to be positively controlled (e.g., powered down). During the conduct of training and testing activities, there is typically at least one, if not numerous, support personnel involved in the activity (e.g., range support personnel aboard a torpedo retrieval boat or support aircraft). In addition to the Lookout posted for the purpose of mitigation, these additional personnel observe for and disseminate marine species sighting information amongst the units participating in the activity whenever possible as they conduct their primary mission responsibilities. However, as a conservative approach to assigning mitigation effectiveness factors, the Navy elected to only account for the minimum number of required Lookouts used for each activity; therefore, the mitigation effectiveness factors may underestimate the likelihood that some marine mammals may be detected during activities that are supported by additional personnel who may also be observing the mitigation zone. The Navy used the equations in the below sections to calculate the reduction in model-estimated mortality impacts due to implementing mitigation. Equation 1: Mitigation Effectiveness = Species Sightability x Visibility x Observation Area x Positive Control Whereas, Species Sightability is the ability to detect marine mammals is dependent on the animal's presence at the surface and the characteristics of the animal that influence its sightability. The Navy considered applicable data from the best available science to numerically approximate the sightability of marine mammals and determined that the standard ``detection probability'' referred to as g(0). Also, Visibility = 1-sum of individual visibility reduction factors; Observation Area = portion of impact range that can be continuously observed during an event; and Positive Control = positive control factor of all sound sources involving mitigation. For further details on these mitigation effectiveness factors please refer to the technical report titled Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing report (U.S. Department of the Navy, 2017b). To quantify the number of marine mammals predicted to be sighted by Lookouts during implementation of mitigation in the range to injury (PTS) for sonar and other transducers, the species sightability is multiplied by the mitigation effectiveness scores and number of model- estimated PTS impacts, as shown in the equation below: Equation 2: Number of Animals Sighted by Lookouts = Mitigation Effectiveness x Model-Estimated Impacts The marine mammals sighted by Lookouts during implementation of mitigation in the range to PTS, as calculated by the equation above, would avoid being exposed to these higher level impacts. The Navy corrects the category of predicted impact for the number of animals sighted within the mitigation zone (e.g., shifts PTS to TTS), but does not modify the total number of [[Page 29958]] animals predicted to experience impacts from the scenario. To quantify the number of marine mammals predicted to be sighted by Lookouts during implementation of mitigation in the range to mortality during events using explosives, the species sightability is multiplied by the mitigation effectiveness scores and number of model-estimated mortality impacts, as shown in equation 1 above. The marine mammals and sea turtles predicted to be sighted by Lookouts during implementation of mitigation in the range to mortality, as calculated by the above equation 2, are predicted to avoid exposure in these ranges. The Navy corrects the category of predicted impact for the number of animals sighted within the mitigation zone, but does not modify the total number of animals predicted to experience impacts from the scenario. For example, the number of animals sighted (i.e., number of animals that will avoid mortality) is first subtracted from the model-predicted mortality impacts, and then added to the model-predicted injurious impacts. NMFS coordinated with the Navy in the development of this quantitative method to address the effects of mitigation on acoustic exposures and explosive takes, and NMFS concurs with the Navy that it is appropriate to incorporate into the take estimates based on the best available science. For additional information on the quantitative analysis process and mitigation measures, refer to the technical report titled Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing report (U.S. Department of the Navy, 2017b) and Section 6 (Take Estimates for Marine Mammals) and Section 11 (Mitigation Measures) of the Navy's rulemaking/LOA application. Summary of Proposed Authorized Take From Training and Testing Activities Based on the methods outlined in the previous sections and the Navy's model and the quantitative assessment of mitigation, the Navy summarizes the take request for acoustic and explosive sources for training and testing activities both annually (based on the maximum number of activities per 12-month period) and over a 5-year period. NMFS has reviewed the Navy's data and analysis and preliminary determined that it is complete and accurate and that the takes by harassment proposed for authorization are reasonably expected to occur and that the takes by mortality could occur as in the case of vessel strikes. Five-year total impacts may be less than the sum total of each year because although the annual estimates are based on the maximum estimated takes, five-year estimates are based on the sum of two maximum years and three nominal years. Nonlethal Take Reasonably Expected To Occur From Training Activities Table 41 summarizes the Navy's take request and the amount and type of take that is reasonably likely to occur (Level A and Level B harassment) by species associated with all training activities. Note that Level B harassment take includes both behavioral disruption and TTS. Figures 6-12 through 6-50 in Section 6 of the Navy's rulemaking/ LOA application illustrate the comparative amounts of TTS and behavioral disruption (at the level of a take) for each species, noting that if a ``taken'' animat was exposed to both TTS and behavioral disruption in the model, it was recorded as a TTS. Table 41--Species-Specific Proposed Take Authorization for Acoustic and Explosive Effects for All Training Activities in the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Annual 5-Year total ** Species Stock --------------------------------------------------------------- Level B Level A Level B Level A ---------------------------------------------------------------------------------------------------------------- Suborder Mysticeti (baleen whales) ---------------------------------------------------------------------------------------------------------------- Family Balaenopteridae (rorquals) ---------------------------------------------------------------------------------------------------------------- Blue whale *.................. Central North 34 0 139 0 Pacific. Eastern North 1,155 1 5,036 3 Pacific. Bryde's whale [dagger]........ Eastern Tropical 27 0 118 0 Pacific. Hawaiian 105 0 429 0 [dagger]. Fin whale *................... California, 1,245 0 5,482 0 Oregon, and Washington. Hawaiian........ 33 0 133 0 Humpback whale [dagger]....... California, 1,254 1 5,645 3 Oregon, and Washington [dagger]. Central North 5,604 1 23,654 5 Pacific. Minke whale................... California, 649 1 2,920 4 Oregon, and Washington. Hawaiian........ 3,463 1 13,664 2 Sei whale *................... Eastern North 53 0 236 0 Pacific. Hawaiian........ 118 0 453 0 ---------------------------------------------------------------------------------------------------------------- Family Eschrichtiidae ---------------------------------------------------------------------------------------------------------------- Gray whale [dagger]........... Eastern North 2,751 5 11,860 19 Pacific. Western North 4 0 14 0 Pacific [dagger]. ---------------------------------------------------------------------------------------------------------------- Suborder Odontoceti (toothed whales) ---------------------------------------------------------------------------------------------------------------- Family Physeteridae (sperm whale) ---------------------------------------------------------------------------------------------------------------- Sperm whale *................. California, 1,397 0 6,257 0 Oregon, and Washington. Hawaiian........ 1,714 0 7,078 0 ---------------------------------------------------------------------------------------------------------------- Family Kogiidae (sperm whales) ---------------------------------------------------------------------------------------------------------------- Dwarf sperm whale............. Hawaiian........ 13,961 35 57,571 148 [[Page 29959]] Pygmy sperm whale............. Hawaiian........ 5,556 16 22,833 64 Kogia whales.................. California, 6,012 23 27,366 105 Oregon, and Washington. ---------------------------------------------------------------------------------------------------------------- Family Ziphiidae (beaked whales) ---------------------------------------------------------------------------------------------------------------- Baird's beaked whale.......... California, 1,317 0 6,044 0 Oregon, and Washington. Blainville's beaked whale..... Hawaiian........ 3,687 0 16,364 0 Cuvier's beaked whale......... California, 6,965 0 32,185 0 Oregon, and Washington. Hawaiian........ 1,235 0 5,497 0 Longman's beaked whale........ Hawaiian........ 13,010 0 57,172 0 Mesoplodon spp................ California, 3,750 0 17,329 0 Oregon, and Washington. ---------------------------------------------------------------------------------------------------------------- Family Delphinidae (dolphins) ---------------------------------------------------------------------------------------------------------------- Bottlenose dolphin............ California 214 0 876 0 Coastal. California, 31,986 2 142,966 9 Oregon, and Washington Offshore. Hawaiian Pelagic 2,086 0 9,055 0 Kauai & Niihau.. 74 0 356 0 Oahu............ 8,186 1 40,918 5 4-Island........ 152 0 750 0 Hawaii.......... 42 0 207 0 False killer whale [dagger]... Hawaii Pelagic.. 701 0 3,005 0 Main Hawaiian 405 0 1,915 0 Islands Insular[dagger]. Northwestern 256 0 1,094 0 Hawaiian Islands. Fraser's dolphin.............. Hawaiian........ 28,409 1 122,784 3 Killer whale.................. Eastern North 73 0 326 0 Pacific Offshore. Eastern North 135 0 606 0 Pacific Transient/West Coast Transient. Hawaiian........ 84 0 352 0 Long-beaked common dolphin.... California...... 128,994 14 559,540 69 Melon-headed whale............ Hawaiian Islands 2,335 0 9,705 0 Kohala Resident. 182 0 913 0 Northern right whale dolphin California, 56,820 8 253,068 40 Oregon, and Washington. Pacific white-sided dolphin... California, 43,914 3 194,882 12 Oregon, and Washington. Pantropical spotted dolphin... Hawaii Island... 2,585 0 12,603 0 Hawaii Pelagic.. 6,809 0 29,207 0 Oahu............ 4,127 0 20,610 0 4-Island........ 260 0 1,295 0 Pygmy killer whale............ Hawaiian........ 5,816 0 24,428 0 Tropical........ 471 0 2,105 0 Risso's dolphin............... California, 76,276 6 338,560 30 Oregon, and Washington. Hawaiian........ 6,590 0 28,143 0 Rough-toothed dolphin......... Hawaiian........ 4,292 0 18,506 0 NSD \1\......... 0 0 0 0 Short-beaked common dolphin... California, 932,453 46 4,161,283 222 Oregon, and Washington. Short-finned pilot whale...... California, 990 1 4,492 5 Oregon, and Washington. Hawaiian........ 8,594 0 37,077 0 Spinner dolphin............... Hawaii Island... 89 0 433 0 Hawaii Pelagic.. 3,138 0 12,826 0 Kauai & Niihau.. 310 0 1,387 0 Oahu & 4-Island. 1,493 1 7,445 5 Striped dolphin............... California, 119,219 1 550,936 3 Oregon, and Washington. Hawaiian........ 5,388 0 22,526 0 ---------------------------------------------------------------------------------------------------------------- Family Phocoenidae (porpoises) ---------------------------------------------------------------------------------------------------------------- Dall's porpoise............... California, 27,282 137 121,236 634 Oregon, and Washington. ---------------------------------------------------------------------------------------------------------------- Suborder Pinnipedia ---------------------------------------------------------------------------------------------------------------- Family Otariidae (eared seals) ---------------------------------------------------------------------------------------------------------------- California sea lion........... U.S............. 69,543 91 327,136 455 Guadalupe fur seal *.......... Mexico.......... 518 0 2,386 0 Northern fur seal............. California...... 9,786 0 44,017 0 ---------------------------------------------------------------------------------------------------------------- Family Phocidae (true seals) ---------------------------------------------------------------------------------------------------------------- Harbor seal................... California...... 3,119 7 13,636 34 [[Page 29960]] Hawaiian monk seal *.......... Hawaiian........ 139 1 662 3 Northern elephant seal........ California...... 38,169 72 170,926 349 ---------------------------------------------------------------------------------------------------------------- * ESA-listed species (all stocks) within the HSTT Study Area. ** 5-year total impacts may be less than sum total of each year. Not all activities occur every year; some activities occur multiple times within a year; and some activities only occur a few times over course of a 5- year period. [dagger] Only designated stocks are ESA-listed. \1\ NSD: No stock designation. Nonlethal Take Reasonably Expected To Occur From Testing Activities Table 42 summarizes the Navy's take request and the amount and type of take that is reasonably likely to occur (Level A and Level B harassment) by species associated with all testing activities. Note that Level B harassment take includes both behavioral disruption and TTS. Figures 6-12 through 6-50 in Section 6 of the Navy's rulemaking/ LOA application illustrate the comparative amounts of TTS and behavioral disruption (at the level of a take) for each species, noting that if a ``taken'' animat was exposed to both TTS and behavioral disruption in the model, it was recorded as a TTS. Table 42--Species-Specific Proposed Take Authorization for Acoustic and Explosive Sound Source Effects for All Testing Activities in the HSTT Study Area ---------------------------------------------------------------------------------------------------------------- Annual 5-Year total ** Species Stock --------------------------------------------------------------- Level B Level A Level B Level A ---------------------------------------------------------------------------------------------------------------- Suborder Mysticeti (baleen whales) ---------------------------------------------------------------------------------------------------------------- Family Balaenopteridae (rorquals) ---------------------------------------------------------------------------------------------------------------- Blue whale *.................. Central North 14 0 65 0 Pacific. Eastern North 833 0 4,005 0 Pacific. Bryde's whale [dagger]........ Eastern Tropical 14 0 69 0 Pacific. Hawaiian 41 0 194 0 [dagger]. Fin whale *................... California, 980 1 4,695 3 Oregon, and Washington. Hawaiian........ 15 0 74 0 Humpback whale [dagger]....... California, 740 0 3,508 0 Oregon, and Washington [dagger]. Central North 3,522 2 16,777 10 Pacific. Minke whale................... California, 276 0 1,309 0 Oregon, and Washington. Hawaiian........ 1,467 1 6,918 4 Sei whale *................... Eastern North 26 0 124 0 Pacific. Hawaiian........ 49 0 229 0 ---------------------------------------------------------------------------------------------------------------- Family Eschrichtiidae ---------------------------------------------------------------------------------------------------------------- Gray whale [dagger]........... Eastern North 1,920 2 9,277 7 Pacific. Western North 2 0 11 0 Pacific [dagger]. ---------------------------------------------------------------------------------------------------------------- Suborder Odontoceti (toothed whales) ---------------------------------------------------------------------------------------------------------------- Family Physeteridae (sperm whale) ---------------------------------------------------------------------------------------------------------------- Sperm whale *................. California, 1,096 0 5,259 0 Oregon, and Washington. Hawaiian........ 782 0 3,731 0 ---------------------------------------------------------------------------------------------------------------- Family Kogiidae (sperm whales) ---------------------------------------------------------------------------------------------------------------- Dwarf sperm whale............. Hawaiian........ 6,459 29 30,607 140 Pygmy sperm whale............. Hawaiian........ 2,595 13 12,270 60 Kogia whales.................. California, 3,120 15 14,643 67 Oregon, and Washington. ---------------------------------------------------------------------------------------------------------------- Family Ziphiidae (beaked whales) ---------------------------------------------------------------------------------------------------------------- Baird's beaked whale.......... California, 727 0 3,418 0 Oregon, and Washington. Blainville's beaked whale..... Hawaiian........ 1,698 0 8,117 0 Cuvier's beaked whale......... California, 4,461 0 20,919 0 Oregon, and Washington. Hawaiian........ 561 0 2,675 0 Longman's beaked whale........ Hawaiian........ 6,223 0 29,746 0 Mesoplodon spp................ California, 2,402 0 11,262 0 Oregon, and Washington. ---------------------------------------------------------------------------------------------------------------- [[Page 29961]] Family Delphinidae (dolphins) ---------------------------------------------------------------------------------------------------------------- Bottlenose dolphin............ California 1,595 0 7,968 0 Coastal. California, 23,436 1 112,410 4 Oregon, and Washington Offshore. Hawaiian Pelagic 1,242 0 6,013 0 Kauai & Niihau.. 491 0 2,161 0 Oahu............ 475 0 2,294 0 4-Island........ 207 0 778 0 Hawaii.......... 38 0 186 0 False killer whale [dagger]... Hawaii Pelagic.. 340 0 1,622 0 Main Hawaiian 184 0 892 0 Islands Insular [dagger]. Northwestern 125 0 594 0 Hawaiian Islands. Fraser's dolphin.............. Hawaiian........ 12,664 1 60,345 5 Killer whale.................. Eastern North 34 0 166 0 Pacific Offshore. Eastern North 64 0 309 0 Pacific Transient/West Coast Transient. Hawaiian........ 40 0 198 0 Long-beaked common dolphin.... California...... 118,278 6 568,020 24 Melon-headed whale............ Hawaiian Islands 1,157 0 5,423 0 Kohala Resident. 168 0 795 0 Northern right whale dolphin.. California, 41,279 3 198,917 15 Oregon, and Washington. Pacific white-sided dolphin... California, 31,424 2 151,000 8 Oregon, and Washington. Pantropical spotted dolphin... Hawaii Island... 1,409 0 6,791 0 Hawaii Pelagic.. 3,640 0 17,615 0 Oahu............ 202 0 957 0 4-Island........ 458 0 1,734 0 Pygmy killer whale............ Hawaiian........ 2,708 0 13,008 0 Tropical........ 289 0 1,351 0 Risso's dolphin............... California, 49,985 3 240,646 15 Oregon, and Washington. Hawaiian........ 2,808 0 13,495 0 Rough-toothed dolphin......... Hawaiian........ 2,193 0 10,532 0 NSD \1\......... 0 0 0 0 Short-beaked common dolphin... California, 560,120 45 2,673,431 222 Oregon, and Washington. Short-finned pilot whale...... California, 923 0 4,440 0 Oregon, and Washington. Hawaiian........ 4,338 0 20,757 0 Spinner dolphin............... Hawaii Island... 202 0 993 0 Hawaii Pelagic.. 1,396 0 6,770 0 Kauai & Niihau.. 1,436 0 6,530 0 Oahu & 4-Island. 331 0 1,389 0 Striped dolphin............... California, 56,035 2 262,973 10 Oregon, and Washington. Hawaiian........ 2,396 0 11,546 0 ---------------------------------------------------------------------------------------------------------------- Family Phocoenidae (porpoises) ---------------------------------------------------------------------------------------------------------------- Dall's porpoise............... California, 17,091 72 81,611 338 Oregon, and Washington. ---------------------------------------------------------------------------------------------------------------- Suborder Pinnipedia ---------------------------------------------------------------------------------------------------------------- Family Otariidae (eared seals) ---------------------------------------------------------------------------------------------------------------- California sea lion........... U.S............. 48,665 6 237,870 23 Guadalupe fur seal *.......... Mexico.......... 939 0 4,357 0 Northern fur seal............. California...... 5,505 1 26,168 4 ---------------------------------------------------------------------------------------------------------------- Family Phocidae (true seals) ---------------------------------------------------------------------------------------------------------------- Harbor seal................... California...... 2,325 1 11,258 5 Hawaiian monk seal *.......... Hawaiian........ 66 0 254 0 Northern elephant seal........ California...... 22,702 27 107,343 131 ---------------------------------------------------------------------------------------------------------------- * ESA-listed species (all stocks) within the HSTT Study Area. ** 5-year total impacts may be less than sum total of each year. Not all activities occur every year; some activities occur multiple times within a year; and some activities only occur a few times over course of a 5- year period. [dagger] Only designated stocks are ESA-listed. \1\ NSD: No stock designation. [[Page 29962]] Take From Vessel Strikes and Explosives by Serious Injury or Mortality Vessel Strike A detailed analysis for vessel strike is contained in Chapters 5 and 6 the Navy's rulemaking/LOA application. Vessel strike to marine mammals is not associated with any specific training or testing activity but rather is a limited, sporadic, and incidental result of Navy vessel movement within the HSTT Study Area. To support the prediction of strikes that could occur in the five years covered by the rule, the Navy calculated probabilities derived from a Poisson distribution using ship strike data between 2009-2016 in the HSTT Study Area, as well as historical at-sea days in HSTT from 2009-2016 and estimated potential at-sea days for the period from 2019 to 2023 to determine the probabilities of a specific number of strikes (n=0, 1, 2, etc.) over the period from 2019 to 2023. The Navy struck two whales in 2009 (both fin whales) in the HSTT Study Area, and there have been no strikes since that time from activities in the HSTT study area that would be covered by these regulations. The Navy used those two fin whale strikes in their calculations and evaluated data beginning in 2009 as that was the start of the Navy's Marine Species Awareness Training and adoption of additional mitigation measures to address ship strike. However, there have been no incidents of vessel strikes between June 2009 and April 2018 from HSTT Study Area activities. Based on the resulting probabilities presented in the Navy's analysis, there is a 10 percent chance of three strikes over the period from 2019 to 2023. Therefore, the Navy estimates, and NMFS agrees, that there is some probability that it could strike, and take by serious injury or mortality, up to three large whales incidental to training and testing activities within the HSTT Study Area over the course of the five years. The Navy then refined its take request based on the species/stocks most likely to be present in the HSTT Study Area based on documented abundance and where overlap is between a species' common occurrence and core Navy training and testing areas within the HSTT Study Area. To determine which species may be struck, a weight of evidence approach was used to qualitatively rank range complex specific species using historic and current stranding data from NMFS, relative abundance as derived by NMFS for the HSTT Phase II Biological Opinion, and the Navy funded monitoring within each range complex. Results of this approach are presented in Table 5-4 of the Navy's rulemaking/LOA application. The Navy anticipates, and NMFS preliminarily concurs, based on the Navy's ship strike analysis presented in the Navy's rulemaking/LOA application, that three vessel strikes could occur over the course of five years, and that no more than two would involve (and therefore the Navy is requesting no more than two lethal takes from) the following species and stocks: Gray whale (Eastern North Pacific stock); Fin whale (California, Oregon, Washington stock); Humpback whale (California, Oregon, California stock or Mexico DPS); Humpback whale (Central Pacific stock or Hawaii DPS); and Sperm whale (Hawaiian stock). Of the possibility for three vessel strikes over the five years, no more than one would involve the species below; therefore, the Navy is requesting no more than one lethal take from) the following species and stocks: Blue whale (Eastern North Pacific stock); Bryde's whale (Eastern Tropical Pacific stock); Bryde's whale (Hawaiian stock); Humpback whale (California, Oregon, California stock or Central America DPS); Minke whale (California, Oregon, Washington stock); Minke whale (Hawaiian stock); Sperm whale (California, Oregon, Washington stock); Sei whale (Hawaiian stock); and Sei whale (Eastern North Pacific stock). Vessel strikes to the stocks below are very unlikely to occur due to their relatively low occurrence in the Study Area, particularly in core HSTT training and testing subareas, and therefore the Navy is not requesting lethal take authorization for the following species and stocks: Blue whale (Central North Pacific stock); Fin whale (Hawaiian stock); and Gray whale (Western North Pacific stock). Explosives The Navy's model and quantitative analysis process used for the HSTT DEIS/OEIS and in the Navy's rulemaking/LOA application to estimate potential exposures of marine mammals to explosive stressors is detailed in the technical report titled Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing report (U.S. Department of the Navy, 2017b). Specifically, over the course of a year, the Navy's model and quantitative analysis process estimates mortality of two short-beaked common dolphin and one California sea lion as a result of exposure to explosive training and testing activities (please refer to section 6 of the Navy's rule making/LOA application). Over the 5[hyphen]year period of the regulations being requested, mortality of 10 marine mammals in total (6 short-beaked common dolphins and 4 California sea lions) is estimated as a result of exposure to explosive training and testing activities. NMFS coordinated with the Navy in the development of their take estimates and concurs with the Navy's proposed approach for estimating the number of animals from each species that could be affected by mortality takes from explosives. Proposed Mitigation Measures Under section 101(a)(5)(A) of the MMPA, NMFS must set forth the ``permissible methods of taking pursuant to such activity, and other means of effecting the least practicable adverse impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such species or stock for subsistence uses'' (``least practicable adverse impact''). NMFS does not have a regulatory definition for least practicable adverse impact. The NDAA for FY 2004 amended the MMPA as it relates to military readiness activities and the incidental take authorization process such that a determination of ``least practicable adverse impact'' shall include consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the ``military readiness activity.'' In Conservation Council for Hawaii v. National Marine Fisheries Service, 97 F. Supp.3d 1210, 1229 (D. Haw. 2015), the Court stated that NMFS ``appear[s] to think [it] satisf[ies] the statutory `least practicable adverse impact' requirement with a `negligible impact' finding.'' More recently, expressing similar concerns in a challenge to a U.S. Navy Operations of Surveillance Towed Array Sensor System Low Frequency Active Sonar (SURTASS LFA) incidental take rule (77 FR 50290), the Ninth Circuit Court of Appeals in Natural Resources Defense Council (NRDC) v. Pritzker, 828 F.3d 1125, 1134 (9th Cir. 2016), stated, ``[c]ompliance with the `negligible impact' requirement does not mean there [is] compliance with the `least [[Page 29963]] practicable adverse impact' standard.'' As the Ninth Circuit noted in its opinion, however, the Court was interpreting the statute without the benefit of NMFS's formal interpretation. We state here explicitly that NMFS is in full agreement that the ``negligible impact'' and ``least practicable adverse impact'' requirements are distinct, even though both statutory standards refer to species and stocks. With that in mind, we provide further explanation of our interpretation of least practicable adverse impact, and explain what distinguishes it from the negligible impact standard. This discussion is consistent with, and expands upon, previous rules we have issued (such as the Navy Gulf of Alaska rule (82 FR 19530; April 27, 2017)). Before NMFS can issue incidental take regulations under section 101(a)(5)(A) of the MMPA, it must make a finding that the total taking will have a ``negligible impact'' on the affected ``species or stocks'' of marine mammals. NMFS's and U.S. Fish and Wildlife Service's implementing regulations for section 101(a)(5) both define ``negligible impact'' as ``an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival'' (50 CFR 216.103 and 50 CFR 18.27(c)). Recruitment (i.e., reproduction) and survival rates are used to determine population growth rates \2\ and, therefore are considered in evaluating population level impacts. --------------------------------------------------------------------------- \2\ A growth rate can be positive, negative, or flat. --------------------------------------------------------------------------- As we stated in the preamble to the final rule for the incidental take implementing regulations, not every population-level impact violates the negligible impact requirement. The negligible impact standard does not require a finding that the anticipated take will have ``no effect'' on population numbers or growth rates: ``The statutory standard does not require that the same recovery rate be maintained, rather that no significant effect on annual rates of recruitment or survival occurs. [T]he key factor is the significance of the level of impact on rates of recruitment or survival.'' (54 FR 40338, 40341-42; September 29, 1989). While some level of impact on population numbers or growth rates of a species or stock may occur and still satisfy the negligible impact requirement--even without consideration of mitigation--the least practicable adverse impact provision separately requires NMFS to prescribe means of ``effecting the least practicable adverse impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance'' 50 CFR 216.102(b), which are typically identified as mitigation measures.\3\ --------------------------------------------------------------------------- \3\ For purposes of this discussion we omit reference to the language in the standard for least practicable adverse impact that says we also must mitigate for subsistence impacts because they are not at issue in this rule. --------------------------------------------------------------------------- The negligible impact and least practicable adverse impact standards in the MMPA both call for evaluation at the level of the ``species or stock.'' The MMPA does not define the term ``species.'' However, Merriam-Webster Dictionary defines ``species'' to include ``related organisms or populations potentially capable of interbreeding.'' See www.merriam-webster.com/dictionary/species (emphasis added). The MMPA defines ``stock'' as ``a group of marine mammals of the same species or smaller taxa in a common spatial arrangement that interbreed when mature.'' 16 U.S.C. 1362(11). The definition of ``population'' is ``a group of interbreeding organisms that represents the level of organization at which speciation begins.'' www.merriam-webster.com/dictionary/population. The definition of ``population'' is strikingly similar to the MMPA's definition of ``stock,'' with both involving groups of individuals that belong to the same species and located in a manner that allows for interbreeding. In fact, the term ``stock'' in the MMPA is interchangeable with the statutory term ``population stock.'' 16 U.S.C. 1362(11). Thus, the MMPA terms ``species'' and ``stock'' both relate to populations, and it is therefore appropriate to view both the negligible impact standard and the least practicable adverse impact standard, both of which call for evaluation at the level of the species or stock, as having a population-level focus. This interpretation is consistent with Congress's statutory findings for enacting the MMPA, nearly all of which are most applicable at the species or stock (i.e., population) level. See 16 U.S.C. 1361 (finding that it is species and population stocks that are or may be in danger of extinction or depletion; that it is species and population stocks that should not diminish beyond being significant functioning elements of their ecosystems; and that it is species and population stocks that should not be permitted to diminish below their optimum sustainable population level). Annual rates of recruitment (i.e., reproduction) and survival are the key biological metrics used in the evaluation of population-level impacts, and accordingly these same metrics are also used in the evaluation of population level impacts for the least practicable adverse impact standard. Recognizing this common focus of the least practicable adverse impact and negligible impact provisions on the ``species or stock'' does not mean we conflate the two standards; despite some common statutory language, we recognize the two provisions are different and have different functions. First, a negligible impact finding is required before NMFS can issue an incidental take authorization. Although it is acceptable to use the mitigation measures to reach a negligible impact finding (see 50 CFR 216.104(c)), no amount of mitigation can enable NMFS to issue an incidental take authorization for an activity that still would not meet the negligible impact standard. Moreover, even where NMFS can reach a negligible impact finding--which we emphasize does allow for the possibility of some ``negligible'' population-level impact--the agency must still prescribe measures that will affect the least practicable amount of adverse impact upon the affected species or stock. Section 101(a)(5)(A)(i)(II) requires NMFS to issue, in conjunction with its authorization, binding--and enforceable--restrictions (in the form of regulations) setting forth how the activity must be conducted, thus ensuring the activity has the ``least practicable adverse impact'' on the affected species or stocks. In situations where mitigation is specifically needed to reach a negligible impact determination, section 101(a)(5)(A)(i)(II) also provides a mechanism for ensuring compliance with the ``negligible impact'' requirement. Finally, we reiterate that the least practicable adverse impact standard also requires consideration of measures for marine mammal habitat, with particular attention to rookeries, mating grounds, and other areas of similar significance, and for subsistence impacts; whereas the negligible impact standard is concerned solely with conclusions about the impact of an activity on annual rates of recruitment and survival.\4\ --------------------------------------------------------------------------- \4\ Outside of the military readiness context, mitigation may also be appropriate to ensure compliance with the ``small numbers'' language in MMPA sections 101(a)(5)(A) and (D). --------------------------------------------------------------------------- In NRDC v. Pritzker, the Court stated, ``[t]he statute is properly read to mean that even if population levels are not threatened significantly, still the agency must adopt mitigation measures aimed at protecting marine mammals to the greatest extent practicable in light of [[Page 29964]] military readiness needs.'' Id. at 1134 (emphases added). This statement is consistent with our understanding stated above that even when the effects of an action satisfy the negligible impact standard (i.e., in the Court's words, ``population levels are not threatened significantly''), still the agency must prescribe mitigation under the least practicable adverse impact standard. However, as the statute indicates, the focus of both standards is ultimately the impact on the affected ``species or stock,'' and not solely focused on or directed at the impact on individual marine mammals. We have carefully reviewed and considered the Ninth Circuit's opinion in NRDC v. Pritzker in its entirety. While the Court's reference to ``marine mammals'' rather than ``marine mammal species or stocks'' in the italicized language above might be construed as a holding that the least practicable adverse impact standard applies at the individual ``marine mammal'' level, i.e., that NMFS must require mitigation to minimize impacts to each individual marine mammal unless impracticable, we believe such an interpretation reflects an incomplete appreciation of the Court's holding. In our view, the opinion as a whole turned on the Court's determination that NMFS had not given separate and independent meaning to the least practicable adverse impact standard apart from the negligible impact standard, and further, that the Court's use of the term ``marine mammals'' was not addressing the question of whether the standard applies to individual animals as opposed to the species or stock as a whole. We recognize that while consideration of mitigation can play a role in a negligible impact determination, consideration of mitigation measures extends beyond that analysis. In evaluating what mitigation measures are appropriate, NMFS considers the potential impacts of the Specified Activities, the availability of measures to minimize those potential impacts, and the practicability of implementing those measures, as we describe below. Implementation of Least Practicable Adverse Impact Standard Given the NRDC v. Pritzker decision, we discuss here how we determine whether a measure or set of measures meets the ``least practicable adverse impact'' standard. Our separate analysis of whether the take anticipated to result from Navy's activities meets the ``negligible impact'' standard appears in the section ``Preliminary Negligible Impact Analysis and Determination'' below. Our evaluation of potential mitigation measures includes consideration of two primary factors: (1) The manner in which, and the degree to which, implementation of the potential measure(s) is expected to reduce adverse impacts to marine mammal species or stocks, their habitat, and their availability for subsistence uses (where relevant). This analysis considers such things as the nature of the potential adverse impact (such as likelihood, scope, and range), the likelihood that the measure will be effective if implemented, and the likelihood of successful implementation; and (2) The practicability of the measures for applicant implementation. Practicability of implementation may consider such things as cost, impact on operations, and, in the case of a military readiness activity, specifically considers personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. 16 U.S.C. 1371(a)(5)(A)(ii). While the language of the least practicable adverse impact standard calls for minimizing impacts to affected species or stocks, we recognize that the reduction of impacts to those species or stocks accrues through the application of mitigation measures that limit impacts to individual animals. Accordingly, NMFS's analysis focuses on measures designed to avoid or minimize impacts on marine mammals from activities that are likely to increase the probability or severity of population-level effects. While complete information on impacts to species or stocks from a specified activity is not available for every activity type, and additional information would help NMFS and the Navy better understand how specific disturbance events affect the fitness of individuals of certain species, there have been significant improvements in understanding the process by which disturbance effects are translated to the population. With recent scientific advancements (both marine mammal energetic research and the development of energetic frameworks), the relative likelihood or degree of impacts on species or stocks may typically be predicted given a detailed understanding of the activity, the environment, and the affected species or stocks. This same information is used in the development of mitigation measures and helps us understand how mitigation measures contribute to lessening effects to species or stocks. We also acknowledge that there is always the potential that new information, or a new recommendation that we had not previously considered, becomes available and necessitates reevaluation of mitigation measures (which may be addressed through adaptive management) to see if further reductions of population impacts are possible and practicable. In the evaluation of specific measures, the details of the specified activity will necessarily inform each of the two primary factors discussed above (expected reduction of impacts and practicability), and are carefully considered to determine the types of mitigation that are appropriate under the least practicable adverse impact standard. Analysis of how a potential mitigation measure may reduce adverse impacts on a marine mammal stock or species, consideration of personnel safety, practicality of implementation, and consideration of the impact on effectiveness of military readiness activities are not issues that can be meaningfully evaluated through a yes/no lens. The manner in which, and the degree to which, implementation of a measure is expected to reduce impacts, as well as its practicability in terms of these considerations, can vary widely. For example, a time/area restriction could be of very high value for decreasing population-level impacts (e.g., avoiding disturbance of feeding females in an area of established biological importance) or it could be of lower value (e.g., decreased disturbance in an area of high productivity but of less firmly established biological importance). Regarding practicability, a measure might involve restrictions in an area or time that impede the Navy's ability to certify a strike group (higher impact on mission effectiveness), or it could mean delaying a small in-port training event by 30 minutes to avoid exposure of a marine mammal to injurious levels of sound (lower impact). A responsible evaluation of ``least practicable adverse impact'' will consider the factors along these realistic scales. Accordingly, the greater the likelihood that a measure will contribute to reducing the probability or severity of adverse impacts to the species or stock or their habitat, the greater the weight that measure is given when considered in combination with practicability to determine the appropriateness of the mitigation measure, and vice versa. In the evaluation of specific measures, the details of the specified activity will necessarily inform each of the two primary factors discussed above (expected reduction of impacts and [[Page 29965]] practicability), and will be carefully considered to determine the types of mitigation that are appropriate under the least practicable adverse impact standard. We discuss consideration of these factors in greater detail below. 1. Reduction of adverse impacts to marine mammal species or stocks and their habitat.\5\ The emphasis given to a measure's ability to reduce the impacts on a species or stock considers the degree, likelihood, and context of the anticipated reduction of impacts to individuals (and how many individuals) as well as the status of the species or stock. --------------------------------------------------------------------------- \5\ We recognize the least practicable adverse impact standard requires consideration of measures that will address minimizing impacts on the availability of the species or stocks for subsistence uses where relevant. Because subsistence uses are not implicated for this action we do not discuss them. However, a similar framework would apply for evaluating those measures, taking into account the MMPA's directive that we make a finding of no unmitigable adverse impact on the availability of the species or stocks for taking for subsistence, and the relevant implementing regulations. --------------------------------------------------------------------------- The ultimate impact on any individual from a disturbance event (which informs the likelihood of adverse species- or stock-level effects) is dependent on the circumstances and associated contextual factors, such as duration of exposure to stressors. Though any proposed mitigation needs to be evaluated in the context of the specific activity and the species or stocks affected, measures with the following types of effects have greater value in reducing the likelihood or severity of adverse species- or stock-level impacts: Avoiding or minimizing injury or mortality; limiting interruption of known feeding, breeding, mother/young, or resting behaviors; minimizing the abandonment of important habitat (temporally and spatially); minimizing the number of individuals subjected to these types of disruptions; and limiting degradation of habitat. Mitigating these types of effects is intended to reduce the likelihood that the activity will result in energetic or other types of impacts that are more likely to result in reduced reproductive success or survivorship. It is also important to consider the degree of impacts that are expected in the absence of mitigation in order to assess the added value of any potential measures. Finally, because the least practicable adverse impact standard gives NMFS discretion to weigh a variety of factors when determining what should be included as appropriate mitigation measures and because the focus is on reducing impacts at the species or stock level, it does not compel mitigation for every kind of take, or every individual taken, even when practicable for implementation by the applicant. The status of the species or stock is also relevant in evaluating the appropriateness of potential mitigation measures in the context of least practicable adverse impact. The following are examples of factors that may (either alone, or in combination) result in greater emphasis on the importance of a mitigation measure in reducing impacts on a species or stock: The stock is known to be decreasing or status is unknown, but believed to be declining; the known annual mortality (from any source) is approaching or exceeding the Potential Biological Removal (PBR) level (as defined in 16 U.S.C. 1362(20)); the affected species or stock is a small, resident population; or the stock is involved in a UME or has other known vulnerabilities, such as recovering from an oil spill. Habitat mitigation, particularly as it relates to rookeries, mating grounds, and areas of similar significance, is also relevant to achieving the standard and can include measures such as reducing impacts of the activity on known prey utilized in the activity area or reducing impacts on physical habitat. As with species- or stock-related mitigation, the emphasis given to a measure's ability to reduce impacts on a species or stock's habitat considers the degree, likelihood, and context of the anticipated reduction of impacts to habitat. Because habitat value is informed by marine mammal presence and use, in some cases there may be overlap in measures for the species or stock and for use of habitat. We consider available information indicating the likelihood of any measure to accomplish its objective. If evidence shows that a measure has not typically been effective nor successful, then either that measure should be modified or the potential value of the measure to reduce effects should be lowered. 2. Practicability. Factors considered may include cost, impact on operations, and, in the case of a military readiness activity, personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity (16 U.S.C. 1371(a)(5)(A)(ii)). NMFS reviewed the Specified Activities and the proposed mitigation measures as described in the Navy's rulemaking/LOA application and the HSTT DEIS/OEIS to determine if they would result in the least practicable adverse effect on marine mammals. NMFS worked with the Navy in the development of the Navy's initially proposed measures, which are informed by years of implementation and monitoring. A complete discussion of the evaluation process used to develop, assess, and select mitigation measures, which was informed by input from NMFS, can be found in Chapter 5 (Mitigation) and Appendix K (Geographic Mitigation Assessment) of the HSTT DEIS/OEIS and is summarized below. We agree that the process described in Chapter 5 and Appendix K of the HSTT DEIS/OEIS is an accurate and appropriate process for evaluating whether the mitigation measures proposed in this rule meet the least practicable adverse impact standard for the testing and training activities in this proposed rule. The Navy proposes to implement these mitigation measures to avoid potential impacts from acoustic, explosive, and physical disturbance and strike stressors. In summary (and described in more detail below), the Navy proposes procedural mitigation measures that we find will reduce the probability and/or severity of impacts expected to result from acute exposure to acoustic sources or explosives, ship strike, and impacts to marine mammal habitat. Specifically, the Navy would use a combination of delayed starts, powerdowns, and shutdowns to minimize or avoid serious injury or mortality, minimize the likelihood or severity of PTS or other injury, and reduce instances of TTS or more severe behavioral disruption caused by acoustic sources or explosives. The Navy also proposes to implement multiple time/area restrictions (several of which have been added since the Phase II rule) that would reduce take of marine mammals in areas or at times where they are known to engage in important behaviors, such as feeding or calving, where the disruption of those behaviors would have a higher probability of resulting in impacts on reproduction or survival of individuals that could lead to population-level impacts. The Navy assessed the practicability of the measures it proposed in the context of personnel safety, practicality of implementation, and their impacts on the Navy's ability to meet their Title 10 requirements and found that the measures were supportable. As summarized in this paragraph and described in more detail below, NMFS has evaluated the measures the Navy has proposed in the manner described earlier in this section (i.e., in consideration of their ability to reduce adverse impacts on marine mammal species or stocks and their habitat and their practicability for implementation) and has determined that the measures will both significantly and adequately reduce impacts on the affected marine [[Page 29966]] mammal species or stocks and their habitat and be practicable for Navy implementation. Therefore, the mitigation measures assure that Navy's activities will have the least practicable adverse impact on the species and stocks and their habitat. The Navy also evaluated numerous measures in the Navy's HSTT DEIS/ OEIS that are not included in the Navy's rulemaking/LOA application for the Specified Activities, and NMFS preliminarily concurs with Navy's analysis that their inclusion was not appropriate under the least practicable adverse impact standard based on our assessment. The Navy considers these additional potential mitigation measures in two groups. Chapter 5 of the HSTT DEIS/OEIS, in the ``Measures Considered but Eliminated'' section, includes an analysis of an array of different types of mitigation that have been recommended over the years by NGOs or the public, through scoping or public comment on environmental compliance documents. Appendix K of the HSTT DEIS/OEIS includes an in- depth analysis of time/area restrictions that have been recommended over time or previously implemented as a result of litigation. As described in Chapter 5 of the DEIS/OEIS, commenters sometimes recommend that the Navy reduce their overall amount of training, reduce explosive use, modify their sound sources, completely replace live training with computer simulation, or include time of day restrictions. All of these proposed measures could potentially reduce the number of marine mammals taken, via direct reduction of the activities or amount of sound energy put in the water. However, as the Navy has described in Chapter 5 of the HSTT DEIS/OEIS, they need to train and test in the conditions in which they fight--and these types of modifications fundamentally change the activity in a manner that would not support the purpose and need for the training and testing (i.e., are entirely impracticable) and therefore are not considered further. NMFS finds the Navy's explanation for why adoption of these recommendations would unacceptably undermine the purpose of the testing and training persuasive. In addition, NMFS must rely on Navy's judgment to a great extent on issues such as its personnel's safety, practicability of Navy's implementation, and extent to which a potential measure would undermine the effectiveness of Navy's testing and training. For these reasons, NMFS finds that these measures do not meet the least practicable adverse impact standard because they are not practicable. Second in Chapter 5 of the DEIS/OEIS, the Navy evaluated additional potential procedural mitigation measures, including increased mitigation zones, ramp-up measures, additional passive acoustic and visual monitoring, and decreased vessel speeds. Some of these measures have the potential to incrementally reduce take to some degree in certain circumstances, though the degree to which this would occur is typically low or uncertain. However, as described in the Navy's analysis, the impracticability of implementation outweighed the potential reduction of impacts to marine mammal species or stocks (see Chapter 5 of HSTT DEIS/OEIS). NMFS reviewed the Navy's evaluation and concurred with this assessment that this additional mitigation was not warranted. Appendix K describes a comprehensive method for analyzing potential geographic mitigation that includes consideration of both a biological assessment of how the potential time/area limitation would benefit the species or stock and its habitat (e.g., is a key area of biological importance or would result in avoidance or reduction of impacts) in the context of the stressors of concern in the specific area and an operational assessment of the practicability of implementation (e.g., including an assessment of the specific importance of that area for training--considering proximity to training ranges and emergency landing fields and other issues). The analysis analyzes an extensive list of areas including Biologically Important Areas, areas agreed to under the HSTT settlement agreement, areas identified by the California Coastal Commission, and areas suggested during scoping. For the areas that were agreed to under the settlement agreement, the Navy notes two important facts that NMFS generally concurs with: (1) The measures were derived pursuant to negotiations with plaintiffs and were specifically not evaluated or selected based on the examination of the best available science that NMFS typically applies to a mitigation assessment and; (2) the Navy's adoption of restrictions on its activities as part of a relatively short-term settlement does not mean that those restrictions are practicable to implement over the longer term. Navy has proposed several time/area mitigations that were not included in the Phase II HSTT regulations. For the areas that are not included in the proposed regulations, though, the Navy found that on balance, the mitigation was not warranted because the anticipated reduction of adverse impacts on marine mammal species or stock and their habitat was not sufficient to offset the impracticability of implementation (in some cases potential benefits to marine mammals were limited to non-existent, in others the consequences on mission effectiveness were too great). NMFS has reviewed the Navy's analysis (Chapter 5 and Appendix K referenced above), which considers the same factors that NMFS would consider to satisfy the least practical adverse impact standard, and has preliminarily concurred with the conclusions, and is not proposing to include any of the measures that the Navy ruled out in the proposed regulations. Below are the mitigation measures that NMFS determined will ensure the least practicable adverse impact on all affected species and stocks and their habitat, including the specific considerations for military readiness activities. The following sections summarize the mitigation measures that will be implemented in association with the training and testing activities analyzed in this document. The mitigation measures are organized into two categories: Procedural mitigation and mitigation areas. Procedural Mitigation Procedural mitigation is mitigation that the Navy will implement whenever and wherever an applicable training or testing activity takes place within the HSTT Study Area. The Navy customizes procedural mitigation for each applicable activity category or stressor. Procedural mitigation generally involves: (1) The use of one or more trained Lookouts to diligently observe for specific biological resources (including marine mammals) within a mitigation zone, (2) requirements for Lookouts to immediately communicate sightings of specific biological resources to the appropriate watch station for information dissemination, and (3) requirements for the watch station to implement mitigation (e.g., halt an activity) until certain recommencement conditions have been met. The first procedural mitigation (Table 42) is designed to aid Lookouts and other applicable personnel with their observation, environmental compliance, and reporting responsibilities. The remainder of the procedural mitigations (Tables 43 through Tables 62) are organized by stressor type and activity category and includes acoustic stressors (i.e., active sonar, air guns, pile driving, weapons firing noise), explosive stressors (i.e., sonobuoys, torpedoes, medium-caliber and large-caliber [[Page 29967]] projectiles, missiles and rockets, bombs, sinking exercises, mines, underwater demolition multiple charge mat weave and obstacles loading, anti-swimmer grenades), and physical disturbance and strike stressors (i.e., vessel movement, towed in-water devices, small-, medium-, and large-caliber non-explosive practice munitions, non-explosive missiles and rockets, non-explosive bombs and mine shapes). Table 43--Procedural Mitigation for Environmental Awareness and Education ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: All training and testing activities, as applicable. Mitigation Zone Size and Mitigation Requirements: Appropriate personnel involved in mitigation and training or testing activity reporting under the Specified Activities will complete one or more modules of the U.S. Navy Afloat Environmental Compliance Training Series, as identified in their career path training plan. Modules include: Introduction to the U.S. Navy Afloat Environmental Compliance Training Series. The introductory module provides information on environmental laws (e.g., ESA, MMPA) and the corresponding responsibilities relevant to Navy training and testing. The material explains why environmental compliance is important in supporting the Navy's commitment to environmental stewardship. Marine Species Awareness Training. All bridge watch personnel, Commanding Officers, Executive Officers, maritime patrol aircraft aircrews, anti[hyphen]submarine warfare and mine warfare rotary-wing aircrews, Lookouts, and equivalent civilian personnel must successfully complete the Marine Species Awareness Training prior to standing watch or serving as a Lookout. The Marine Species Awareness Training provides information on sighting cues, visual observation tools and techniques, and sighting notification procedures. Navy biologists developed Marine Species Awareness Training to improve the effectiveness of visual observations for biological resources, focusing on marine mammals and sea turtles, and including floating vegetation, jellyfish aggregations, and flocks of seabirds. U.S. Navy Sonar Positional Reporting System and Marine Mammal Incident Reporting. This module provides instruction on the procedures and activity reporting requirements for the Sonar Positional Reporting System and marine mammal incident reporting. U.S. Navy Protective Measures Assessment Protocol. This module provides the necessary instruction for accessing mitigation requirements during the event planning phase using the Protective Measures Assessment Protocol software tool. Also related are annual marine mammal awareness messages promulgated annually to Fleet units: For Hawaii: Humpback Whale Awareness Notification Message Area (November 15-April 15): --The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including humpback whales. --To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species (including humpback whales), that when concentrated seasonally, may become vulnerable to vessel strikes. --Lookouts will use the information from the awareness notification message to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. For Southern California: Blue Whale Awareness Notification Message Area (June 1-October 31): --The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including blue whales. --To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species (including blue whales), that when concentrated seasonally, may become vulnerable to vessel strikes. --Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. Gray Whale Awareness Notification Message Area (November 1-March 31): --The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including gray whales. --To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species (including gray whales), that when concentrated seasonally, may become vulnerable to vessel strikes. --Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. Fin Whale Awareness Notification Message Area (November 1-May 31): --The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including fin whales. --To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species (including fin whales), that when concentrated seasonally, may become vulnerable to vessel strikes. --Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in implementation of procedural mitigation. ------------------------------------------------------------------------ Procedural Mitigation for Acoustic Stressors Mitigation measures for acoustic stressors are provided in Tables 44 through 47. Procedural Mitigation for Active Sonar Procedural mitigation for active sonar is described in Table 44 below. [[Page 29968]] Table 44--Procedural Mitigation for Active Sonar ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Low-frequency active sonar, mid-frequency active sonar, high-frequency active sonar. For vessel-based active sonar activities, mitigation applies only to sources that are positively controlled and deployed from manned surface vessels (e.g., sonar sources towed from manned surface platforms). For aircraft-based active sonar activities, mitigation applies only to sources that are positively controlled and deployed from manned aircraft that do not operate at high altitudes (e.g., rotary-wing aircraft). Mitigation does not apply to active sonar sources deployed from unmanned aircraft or aircraft operating at high altitudes (e.g., maritime patrol aircraft). Number of Lookouts and Observation Platform: Hull-mounted sources: Platforms without space or manning restrictions while underway: 2 Lookouts at the forward part of the ship. Platforms with space or manning restrictions while underway: 1 Lookout at the forward part of a small boat or ship Platforms using active sonar while moored or at anchor (including pierside): 1 Lookout Sources that are not hull-mounted: 1 Lookout on the ship or aircraft conducting the activity. Mitigation Zone Size and Mitigation Requirements: Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence use of active sonar. Low-frequency active sonar at 200 dB or more, and hull- mounted mid-frequency active sonar will implement the following mitigation zones: During the activity, observe for marine mammals; power down active sonar transmission by 6 dB if resource is observed within 1,000 yd of the sonar source; power down by an additional 4 dB (10 dB total) if resource is observed within 500 yd of the sonar source; and cease transmission if resource is observed within 200 yd of the sonar source. Low-frequency active sonar below 200 dB, mid-frequency active sonar sources that are not hull-mounted, and high-frequency active sonar will implement the following mitigation zone: During the activity, observe for marine mammals; cease active sonar transmission if resource is observed within 200 yd of the sonar source. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence active sonar transmission until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the sonar source; (3) the mitigation zone has been clear from any additional sightings for 10 min for aircraft-deployed sonar sources or 30 min for vessel- deployed sonar sources; (4) for mobile activities, the active sonar source has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting; or (5) for activities using hull-mounted sonar, the Lookout concludes that dolphins are deliberately closing in on the ship to ride the ship's bow wave, and are therefore out of the main transmission axis of the sonar (and there are no other marine mammal sightings within the mitigation zone). ------------------------------------------------------------------------ Procedural Mitigation for Air Guns Procedural mitigation for air guns is described in Table 45 below. Table 45--Procedural Mitigation for Air Guns ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Air guns. Number of Lookouts and Observation Platform: 1 Lookout positioned on a ship or pierside. Mitigation Zone Size and Mitigation Requirements: 150 yd around the air gun: Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence use of air guns. During the activity, observe for marine mammals; if resource is observed, cease use of air guns. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence the use of air guns until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the air gun; (3) the mitigation zone has been clear from any additional sightings for 30 min; or (4) for mobile activities, the air gun has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ Procedural Mitigation for Pile Driving Procedural mitigation for pile driving is described in Table 46 below. [[Page 29969]] Table 46--Procedural Mitigation for Pile Driving ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Pile driving and pile extraction sound during Elevated Causeway System Training. Number of Lookouts and Observation Platform: 1 Lookout positioned on the shore, the elevated causeway, or a small boat. Mitigation Zone Size and Mitigation Requirements: 100 yd around the pile driver: 30 min prior to the start of the activity, observe for floating vegetation and marine mammals; if resource is observed, do not commence impact pile driving or vibratory pile extraction. During the activity, observe for marine mammals; if resource is observed, cease impact pile driving or vibratory pile extraction. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence pile driving until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the pile driving location; or (3) the mitigation zone has been clear from any additional sightings for 30 min. ------------------------------------------------------------------------ Procedural Mitigation for Weapons Firing Noise Procedural mitigation for weapons firing noise is described in Table 47 below. Table 47--Procedural Mitigation for Weapons Firing Noise ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Weapons firing noise associated with large-caliber gunnery activities. Number of Lookouts and Observation Platform: 1 Lookout positioned on the ship conducting the firing. Depending on the activity, the Lookout could be the same as the one described in Table 50 (Procedural Mitigation for Explosive Medium-Caliber and Large-Caliber Projectiles) or Table 60 (Procedural Mitigation for Small-, Medium-, and Large-Caliber Non- Explosive Practice Munitions) Mitigation Zone Size and Mitigation Requirements: 30 degrees on either side of the firing line out to 70 yd from the muzzle of the weapon being fired: Prior to the start of the activity, observe for floating vegetation and marine mammals; if resource is observed, do not commence weapons firing. During the activity, observe for marine mammals; if resource is observed, cease weapons firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence weapons firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the firing ship; (3) the mitigation zone has been clear from any additional sightings for 30 min; or (4) for mobile activities, the firing ship has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ Procedural Mitigation for Explosive Stressors Mitigation measures for explosive stressors are provided in Tables 48 through 52. Procedural Mitigation for Explosive Sonobuoys Procedural mitigation for explosive sonobuoys is described in Table 48 below. Table 48--Procedural Mitigation for Explosive Sonobuoys ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Explosive sonobuoys. Number of Lookouts and Observation Platform: 1 Lookout positioned in an aircraft or on small boat. Mitigation Zone Size and Mitigation Requirements: 600 yd around an explosive sonobuoy: Prior to the start of the activity (e.g., during deployment of a sonobuoy field, which typically lasts 20-30 min), conduct passive acoustic monitoring for marine mammals, and observe for floating vegetation and marine mammals; if resource is visually observed, do not commence sonobuoy or source/receiver pair detonations. During the activity, observe for marine mammals; if resource is observed, cease sonobuoy or source/receiver pair detonations. [[Page 29970]] To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence the use of explosive sonobuoys until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the sonobuoy; or (3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. ------------------------------------------------------------------------ Procedural Mitigation for Explosive Torpedoes Procedural mitigation for explosive torpedoes is described in Table 49 below. Table 49--Procedural Mitigation for Explosive Torpedoes ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Explosive torpedoes. Number of Lookouts and Observation Platform: 1 Lookout positioned in an aircraft. Mitigation Zone Size and Mitigation Requirements: 2,100 yd around the intended impact location: Prior to the start of the activity (e.g., during deployment of the target), conduct passive acoustic monitoring for marine mammals, and observe for floating vegetation, jellyfish aggregations and marine mammals; if resource is visually observed, do not commence firing. During the activity, observe for marine mammals and jellyfish aggregations; if resource is observed, cease firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; or (3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. After completion of the activity, observe for marine mammals; if any injured or dead resources are observed, follow established incident reporting procedures. ------------------------------------------------------------------------ Procedural Mitigation for Medium- and Large-Caliber Projectiles Procedural mitigation for medium- and large-caliber projectiles is described in Table 50 below. Table 50--Procedural Mitigation for Explosive Medium-Caliber and Large- Caliber Projectiles ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Gunnery activities using explosive medium-caliber and large- caliber projectiles. Mitigation applies to activities using a surface target. Number of Lookouts and Observation Platform: 1 Lookout on the vessel or aircraft conducting the activity. Mitigation Zone Size and Mitigation Requirements: 200 yd around the intended impact location for air-to- surface activities using explosive medium-caliber projectiles, or 600 yd around the intended impact location for surface-to- surface activities using explosive medium-caliber projectiles, or 1,000 yd around the intended impact location for surface-to- surface activities using explosive large-caliber projectiles: Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence firing. During the activity, observe for marine mammals; if resource is observed, cease firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; (3) the mitigation zone has been clear from any additional sightings for 10 min for aircraft- based firing or 30 min for vessel-based firing; or (4) for activities using mobile targets, the intended impact location has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ [[Page 29971]] Procedural Mitigation for Explosive Missiles and Rockets Procedural mitigation for explosive missiles and rockets is described in Table 51 below. Table 51--Procedural Mitigation for Explosive Missiles and Rockets ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Aircraft-deployed explosive missiles and rockets. Mitigation applies to activities using a surface target. Number of Lookouts and Observation Platform: 1 Lookout positioned in an aircraft. Mitigation Zone Size and Mitigation Requirements: 900 yd around the intended impact location during activities for missiles or rockets with 0.6-20 lb net explosive weight, or 2,000 yd around the intended impact location for missiles with 21-500 lb net explosive weight: Prior to the start of the activity (e.g., during a fly- over of the mitigation zone), observe for floating vegetation and marine mammals; if resource is observed, do not commence firing. During the activity, observe for marine mammals; if resource is observed, cease firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; or (3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. ------------------------------------------------------------------------ Procedural Mitigation for Explosive Bombs Procedural mitigation for explosive bombs is described in Table 52 below. Table 52--Procedural Mitigation for Explosive Bombs ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Explosive bombs. Number of Lookouts and Observation Platform: 1 Lookout positioned in the aircraft conducting the activity. Mitigation Zone Size and Mitigation Requirements: 2,500 yd around the intended target: Prior to the start of the activity (e.g., when arriving on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence bomb deployment. During target approach, observe for marine mammals; if resource is observed, cease bomb deployment. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence bomb deployment until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended target; (3) the mitigation zone has been clear from any additional sightings for 10 min; or (4) for activities using mobile targets, the intended target has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ Procedural Mitigation for Sinking Exercises Procedural mitigation for sinking exercises is described in Table 53 below. Table 53--Procedural Mitigation for Sinking Exercises ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Sinking exercises. Number of Lookouts and Observation Platform: 2 Lookouts (one positioned in an aircraft and one on a vessel). Mitigation Zone Size and Mitigation Requirements: 2.5 nmi around the target ship hulk: 90 min prior to the first firing, conduct aerial observations for floating vegetation, jellyfish aggregations and marine mammals; if resource is observed, do not commence firing. [[Page 29972]] During the activity, conduct passive acoustic monitoring and visually observe for marine mammals from the vessel; if resource is visually observed, cease firing. Immediately after any planned or unplanned breaks in weapons firing of longer than 2 hours, observe for marine mammals from the aircraft and vessel; if resource is observed, do not commence firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the target ship hulk; or (3) the mitigation zone has been clear from any additional sightings for 30 min. For 2 hours after sinking the vessel (or until sunset, whichever comes first), observe for marine mammals; if any injured or dead resources are observed, follow established incident reporting procedures. ------------------------------------------------------------------------ Procedural Mitigation for Explosive Mine Countermeasure and Neutralization Activities Procedural mitigation for explosive mine countermeasure and neutralization activities is described in Table 54 below. Table 54--Procedural Mitigation for Explosive Mine Countermeasure and Neutralization Activities ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Explosive mine countermeasure and neutralization activities. Number of Lookouts and Observation Platform: 1 Lookout positioned on a vessel or in an aircraft when implementing the smaller mitigation zone. 2 Lookouts (one positioned in an aircraft and one on a small boat) when implementing the larger mitigation zone. Mitigaton Zone Size and Mitigation Requirements: 600 yd around the detonation site for activities using 0.1- 5-lb net explosive weight, or 2,100 yd around the detonation site for 6-650 lb net explosive weight (including high explosive target mines): Prior to the start of the activity (e.g., when maneuvering on station; typically, 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained), observe for floating vegetation and marine mammals; if resource is observed, do not commence detonations. During the activity, observe for marine mammals; if resource is observed, cease detonations. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to detonation site; or (3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft with fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. After completion of the activity, observe for marine mammals (typically 10 min when the activity involves aircraft that have fuel constraints or 30 min when the activity involves aircraft that are not typically fuel constrained); if any injured or dead resources are observed, follow established incident reporting procedures. ------------------------------------------------------------------------ Procedural Mitigation for Explosive Mine Neutralization Activities Involving Navy Divers Procedural mitigation for explosive mine neutralization activities involving Navy divers is described in Table 55 below. Table 55--Procedural Mitigation for Explosive Mine Neutralization Activities Involving Navy Divers ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Explosive mine neutralization activities involving Navy divers. Number of Lookouts and Observation Platform: 2 Lookouts (two small boats with one Lookout each, or one Lookout on a small boat and one in a rotary-wing aircraft) when implementing the smaller mitigation zone. 4 Lookouts (two small boats with two Lookouts each), and a pilot or member of an aircrew will serve as an additional Lookout if aircraft are used during the activity, when implementing the larger mitigation zone. Mitigation Zone Size and Mitigation Requirements: The Navy will not set time-delay firing devices (0.1-29 lb net explosive weight) to exceed 10 min. 500 yd around the detonation site during activities under positive control using 0.1-20 lb net explosive weight, or 1,000 yd around the detonation site during all activities using time-delay fuses (0.1-29 lb net explosive weight) and during activities under positive control using 21-60 lb net explosive weight: [[Page 29973]] Prior to the start of the activity (e.g., when maneuvering on station for activities under positive control; 30 min for activities using time-delay firing devices), observe for floating vegetation and marine mammals; if resource is observed, do not commence detonations or fuse initiation. During the activity, observe for marine mammals; if resource is observed, cease detonations or fuse initiation. All divers placing the charges on mines will support the Lookouts while performing their regular duties and will report all sightings to their supporting small boat or Range Safety Officer. To the maximum extent practicable depending on mission requirements, safety, and environmental conditions, boats will position themselves near the mid-point of the mitigation zone radius (but outside of the detonation plume and human safety zone), will position themselves on opposite sides of the detonation location (when two boats are used), and will travel in a circular pattern around the detonation location with one Lookout observing inward toward the detonation site and the other observing outward toward the perimeter of the mitigation zone. If used, aircraft will travel in a circular pattern around the detonation location to the maximum extent practicable. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations or fuse initiation until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the detonation site; (3) the mitigation zone has been clear from any additional sightings for 10 min during activities under positive control with aircraft that have fuel constraints, or 30 min during activities under positive control with aircraft that are not typically fuel constrained and during activities using time-delay firing devices. After completion of an activity using time-delay firing devices, observe for marine mammals for 30 min; if any injured or dead resources are observed, follow established incident reporting procedures. ------------------------------------------------------------------------ Procedural Mitigation for Underwater Demolition Multiple Charge--Mat Weave and Obstacle Loading Procedural mitigation for underwater demolition multiple charge-- mat weave and obstacle Loading is described in Table 56 below. Table 56--Procedural Mitigation for Underwater Demolition Multiple Charge--Mat Weave and Obstacle Loading ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Underwater Demolition Multiple Charge--Mat Weave and Obstacle Loading exercises. Number of Lookouts and Observation Platform: 2 Lookouts (one on a small boat and one on shore from an elevated platform). Mitigation Zone Size and Mitigation Requirements: 700 yd around the detonation site: For 30 min prior to the first detonation, the Lookout positioned on a small boat will observe for floating vegetation and marine mammals; if resource is observed, do not commence the initial detonation. For 10 min prior to the first detonation, the Lookout positioned on shore will use binoculars to observe for marine mammals; if resource is observed, do not commence the initial detonation until the mitigation zone has been clear of any additional sightings for a minimum of 10 min. During the activity, observe for marine mammals; if resource is observed, cease detonations. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the detonation site; or (3) the mitigation zone has been clear from any additional sightings for 10 min (as determined by the shore observer). After completion of the activity, the Lookout positioned on a small boat will observe for marine mammals for 30 min; if any injured or dead resources are observed, follow established incident reporting procedures. ------------------------------------------------------------------------ Procedural Mitigation for Maritime Security Operations--Anti-Swimmer Grenades Procedural mitigation for maritime security operations--anti- swimmer grenades is described in Table 57 below. Table 57--Procedural Mitigation for Maritime Security Operations--Anti- Swimmer Grenades ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Maritime Security Operations--Anti-Swimmer Grenades. [[Page 29974]] Number of Lookouts and Observation Platform: 1 Lookout positioned on the small boat conducting the activity. Mitigation Zone Size and Mitigation Requirements: 200 yd around the intended detonation location: Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence detonations. During the activity, observe for marine mammals; if resource is observed, cease detonations. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence detonations until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended detonation location; (3) the mitigation zone has been clear from any additional sightings for 30 min; or (4) the intended detonation location has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ Procedural Mitigation for Physical Disturbance and Strike Stressors Mitigation measures for physical disturbance and strike stressors are provided in Table 58 through Table 62. Procedural Mitigation for Vessel Movement Procedural mitigation for vessel movement is described in Table 58 below. Table 58--Procedural Mitigation for Vessel Movement ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Vessel movement. The mitigation will not be applied if (1) the vessel's safety is threatened, (2) the vessel is restricted in its ability to maneuver (e.g., during launching and recovery of aircraft or landing craft, during towing activities, when mooring, etc.), (3) the vessel is operated autonomously, or (4) when impracticable based on mission requirements (e.g., during Amphibious Assault-- Battalion Landing exercises). Number of Lookouts and Observation Platform: 1 Lookout on the vessel that is underway. Mitigation Zone Size and Mitigation Requirements: 500 yd around whales: When underway, observe for marine mammals; if a whale is observed, maneuver to maintain distance. 200 yd around all other marine mammals (except bow-riding dolphins and pinnipeds hauled out on man-made navigational structures, port structures, and vessels): When underway, observe for marine mammals; if a marine mammal other than a whale, bow-riding dolphin, or hauled-out pinniped is observed, maneuver to maintain distance. ------------------------------------------------------------------------ Procedural Mitigation for Towed In-Water Devices Procedural mitigation for towed in-water devices is described in Table 59 below. Table 59--Procedural Mitigation for Towed In-Water Devices ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Towed in-water devices. Mitigation applies to devices that are towed from a manned surface platform or manned aircraft. The mitigation will not be applied if the safety of the towing platform or in-water device is threatened. Number of Lookouts and Observation Platform: 1 Lookout positioned on the manned towing platform. Mitigation Zone Size and Mitigation Requirements: 250 yd around marine mammals: During the activity, observe for marine mammals; if resource is observed, maneuver to maintain distance. ------------------------------------------------------------------------ Procedural Mitigation for Small-, Medium-, and Large-Caliber Non- Explosive Practice Munitions Procedural mitigation for small-, medium-, and large-caliber non- explosive practice munitions is described in Table 60 below. [[Page 29975]] Table 60--Procedural Mitigation for Small-, Medium-, and Large-Caliber Non-Explosive Practice Munitions ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Gunnery activities using small-, medium-, and large-caliber non-explosive practice munitions. Mitigation applies to activities using a surface target. Number of Lookouts and Observation Platform: 1 Lookout positioned on the platform conducting the activity. Depending on the activity, the Lookout could be the same as the one described in Table 47 (Procedural Mitigation for Weapons Firing Noise). Mitigation Zone Size and Mitigation Requirements: 200 yd around the intended impact location: Prior to the start of the activity (e.g., when maneuvering on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence firing. During the activity, observe for marine mammals; if resource is observed, cease firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; (3) the mitigation zone has been clear from any additional sightings for 10 min for aircraft- based firing or 30 min for vessel-based firing; or (4) for activities using a mobile target, the intended impact location has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ Procedural Mitigation for Non-Explosive Missiles and Rockets Procedural mitigation for non-explosive missiles and rockets is described in Table 61 below. Table 61--Procedural Mitigation for Non-Explosive Missiles and Rockets ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Aircraft-deployed non-explosive missiles and rockets. Mitigation applies to activities using a surface target. Number of Lookouts and Observation Platform: 1 Lookout positioned in an aircraft. Mitigation Zone Size and Mitigation Requirements: 900 yd around the intended impact location: Prior to the start of the activity (e.g., during a fly- over of the mitigation zone), observe for floating vegetation and marine mammals; if resource is observed, do not commence firing. During the activity, observe for marine mammals; if resource is observed, cease firing. To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence firing until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended impact location; or (3) the mitigation zone has been clear from any additional sightings for 10 min when the activity involves aircraft that have fuel constraints, or 30 min when the activity involves aircraft that are not typically fuel constrained. ------------------------------------------------------------------------ Procedural Mitigation for Non-Explosive Bombs and Mine Shapes Procedural mitigation for non-explosive bombs and mine shapes is described in Table 62 below. Table 62--Procedural Mitigation for Non-Explosive Bombs and Mine Shapes ------------------------------------------------------------------------ Procedural mitigation description ------------------------------------------------------------------------- Stressor or Activity: Non-explosive bombs. Non-explosive mine shapes during mine laying activities. Number of Lookouts and Observation Platform: 1 Lookout positioned in an aircraft. Mitigation Zone Size and Mitigation Requirements: 1,000 yd around the intended target: Prior to the start of the activity (e.g., when arriving on station), observe for floating vegetation and marine mammals; if resource is observed, do not commence bomb deployment or mine laying. During approach of the target or intended minefield location, observe for marine mammals; if resource is observed, cease bomb deployment or mine laying. [[Page 29976]] To allow an observed marine mammal to leave the mitigation zone, the Navy will not recommence bomb deployment or mine laying until one of the recommencement conditions has been met: (1) The animal is observed exiting the mitigation zone; (2) the animal is thought to have exited the mitigation zone based on a determination of its course, speed, and movement relative to the intended target or minefield location; (3) the mitigation zone has been clear from any additional sightings for 10 min; or (4) for activities using mobile targets, the intended target has transited a distance equal to double that of the mitigation zone size beyond the location of the last sighting. ------------------------------------------------------------------------ Mitigation Areas In addition to procedural mitigation, the Navy will implement mitigation measures within mitigation areas to avoid or minimize potential impacts on marine mammals (see the revised Figures provided in the Navy's addendum to the application). A full technical analysis (for which the methods were summarized above) of the mitigation areas that the Navy considered for marine mammals is provided in Appendix K (Geographic Mitigation Assessment) of the HSTT DEIS/OEIS. The Navy has taken into account public comments received from the HSTT DEIS/OEIS, best available science, and the practicability of implementing additional mitigations and has enhanced their mitigation areas and mitigation measures to further reduce impacts to marine mammals, and therefore, the Navy revised their mitigation areas since their application. These revisions are discussed below and can be found as an addendum to the Navy's application at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. The Navy will continue to work with NMFS to finalize its mitigation areas through the development of the rule. Information on the mitigation measures that the Navy will implement within mitigation areas is provided in Tables 63 and 64. The mitigation applies year-round unless specified otherwise in the tables. Mitigation Areas for the HRC Mitigation areas for the HRC are described in Table 63 below. The location of each mitigation area is in the Navy's addendum to the application on Mitigation Areas. Table 63--Mitigation Areas for Marine Mammals in the Hawaii Range Complex ------------------------------------------------------------------------ Mitigation area description ------------------------------------------------------------------------- Stressor or Activity: Sonar. Explosives.\1\ Vessel strikes. Resource Protection Focus: Marine mammals Mitigation Area Requirements: Hawaii Island Mitigation Area (year-round): The Navy will minimize the use of mid-frequency active anti-submarine warfare sensor bins MF1 and MF4 to the maximum extent practicable. The Navy will not conduct more than 300 hrs of MF1 and 20 hrs of MF4 per year. Should national security present a requirement to conduct more than 300 hrs of MF1 or 20 hrs of MF4 per year, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., hours of sonar usage) in its annual activity reports. The Navy will not use explosives \1\ during training and testing. Should national security present a requirement for the use of explosives in the area, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., explosives usage) in its annual activity reports. 4-Islands Region Mitigation Area (November 15-April 15): The Navy will not use mid-frequency active anti- submarine warfare sensor MF1 from November 15-April 15. Should national security present a requirement for the use of MF1 in the area from November 15-April 15, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., hours of sonar usage) in its annual activity reports. Humpback Whale Special Reporting Areas (December 15-April 15): The Navy will report the hours of MF1 used in the special reporting areas in its annual activity reports. Humpback Whale Awareness Notification Message Area (November 1-April 30): The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including humpback whales. To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species (including humpback whales), that when concentrated seasonally, may become vulnerable to vessel strikes. Lookouts will use the information from the awareness notification message to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. ------------------------------------------------------------------------ Notes: \1\ Explosive restrictions for the Hawaii Island Mitigation Area apply only to those activities for which the Navy seeks MMPA authorization (e.g., surface-to-surface or air-to-surface missile and gunnery events, BOMBEX, and mine neutralization). [[Page 29977]] Mitigation Areas for the SOCAL Portion of the Study Area Mitigation areas for the SOCAL portion of the Study Area are described in Table 64 below. The location of each mitigation area is shown in the Navy's addendum to the application on Mitigation Areas. Table 64--Mitigation Areas for Marine Mammals in the Southern California Portion of the Study Area ------------------------------------------------------------------------ Mitigation area description ------------------------------------------------------------------------- Stressor or Activity: Sonar. Explosives. Vessel strikes. Resource Protection Focus: Marine mammals. Mitigation Area Requirements: San Diego Arc Mitigation Area (June 1-October 31): The Navy will minimize the use of mid-frequency active anti-submarine warfare sensor bin MF1 to the maximum extent practicable. The Navy will not conduct more than 200 hrs of MF1 (with the exception of active sonar maintenance and systems checks) per year from June 1-October 31. Should national security present a requirement to conduct more than 200 hrs of MF1 (with the exception of active sonar maintenance and systems checks) per year from June 1-October 31, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., hours of sonar usage) in its annual activity reports. The Navy will not use explosives during large-caliber gunnery, torpedo, bombing, and missile (including 2.75 in rockets) activities during training and testing. Should national security present a requirement to conduct large-caliber gunnery, torpedo, bombing, and missile (including 2.75 in rockets) activities using explosives, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information (e.g., explosives usage) in its annual activity reports. Santa Barbara Island Mitigation Area (year-round): The Navy will not use mid-frequency active anti- submarine warfare sensor MF1 and explosives in small-, medium-, and large-caliber gunnery; torpedo; bombing; and missile (including 2.75 in rockets) activities during unit-level training and major training exercises. Should national security present a requirement for the use of mid-frequency active anti-submarine warfare sensor MF1 or explosives in small-, medium-, and large-caliber gunnery; torpedo; bombing; and missile (including 2.75 in rockets) activities during unit-level training or major training exercises for national security, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in its annual activity reports. Blue Whale (June 1-October 31), Gray Whale (November 1-March 31), and Fin Whale (November 1-May 31) Awareness Notification Message Areas: The Navy will issue a seasonal awareness notification message to alert ships and aircraft operating in the area to the possible presence of concentrations of large whales, including blue, gray, or fin whales. To maintain safety of navigation and to avoid interactions with large whales during transits, the Navy will instruct vessels to remain vigilant to the presence of large whale species, that when concentrated seasonally, may become vulnerable to vessel strikes. Lookouts will use the information from the awareness notification messages to assist their visual observation of applicable mitigation zones during training and testing activities and to aid in the implementation of procedural mitigation. ------------------------------------------------------------------------ NMFS conducted an independent analysis of the mitigation areas that the Navy proposed, which are described below. NMFS concurs with the Navy's analysis, which indicates that the measures in these mitigation areas are both practicable (which is the Navy's purview to determine) and will reduce the likelihood or severity of adverse impacts to marine mammal species or stocks or their habitat in the manner described in the Navy's analysis. Specifically, the mitigation areas will provide the following benefits to the affected stocks: 4-Islands Region Mitigation Area (Seasonal Nov 15-Apr 15): The Maui/Molokai area (4-Islands Region) is an important reproductive and calving area for humpback whales. Recent scientific research indicates peak humpback whale season has expanded, with higher densities of whales occurring earlier than prior studies had indicated. In addition, a portion of this area has also been identified as biologically important for the ESA-listed small and resident population, main Hawaiian Island insular false killer whales. While the season for this area used to be from December 15 to April 15, the Navy has proposed to extend it from November 15 to April 15. Extending the season and size of the 4-Islands Region Mitigation Area will provide some added protection for that species during half of the year. Minimizing impacts in this area and time is expected to reduce the likelihood of more serious impacts from sonar that could interfere with important cow/calf communication or have unforeseen impacts on more sensitive calves. This area also overlaps with identified biologically important areas for other marine mammal species such as dolphin species including Common bottlenose dolphin, pantropical spotted dolphin, and spinner dolphin (small and resident populations). Hawaii Island Mitigation Area (Year-round): The endangered main Hawaiian Island insular false killer whale, which is a small and resident populations, and two species of beaked whales (Cuvier and Blainville's) have been documented using this area year-round to support multiple biological functions. Main Hawaiian Island insular false killer whales are an endangered species and beaked whales are scientifically shown to be highly sensitive to exposure to sonar. This area also overlaps with other identified biologically important areas for other marine mammal species such as humpback whale (important reproductive/calving area), dwarf sperm whale (small and resident populations), pygmy killer whale (small and resident [[Page 29978]] population), melon-headed whale (small and resident population), short- finned pilot whale (small and resident population) and dolphin species including Common bottlenose dolphin, pantropical spotted dolphin, spinner dolphin, and rough-toothed dolphin (small and resident populations) for which the Hawaii Island Mitigation Area would provide additional protection. Potential benefits to humpback whales are noted in the section above. For beaked whales, which have been shown to be more sensitive to loud sounds, a reduction of impacts in general where the stock is known to live or concentrate is expected to reduce the likelihood that more severe responses that could affect individual fitness would occur. For small resident populations, one goal is to ensure that the entirety of any small population is not being extensively impacted, in order to reduce the probability that repeated behavioral exposures to small numbers of individuals will result in energetic impacts, or other impacts with the potential to reduce survival or reproductive success on individuals that will more readily accrue to population level impacts in smaller stocks. Santa Barbara Island Mitigation Area (Year-round): Numerous marine mammal species use the Channel Islands NMS and it provides valuable, and protected, marine mammal habitat. Particularly, this mitigation area will overlap with identified biologically important feeding area for blue whales and migration areas for gray whales. Generally, a reduction of impacts in the Santa Barbara Island Mitigation Area (inclusive of a portion of the Channel Islands NMS) is expected to reduce stressors in an area that likely contains high value habitat that is more typically free of other anthropogenic stressors. San Diego Arc Mitigation Area (Seasonal Jun 1-Oct 31): Endangered blue whales have been documented foraging in this area seasonally. Reducing harassing exposures of marine mammals to sonar and explosives in feeding areas, even when the animals have demonstrated some tolerance for disturbance when in a feeding state, is expected to reduce the likelihood that feeding would be interrupted to a degree that energetic reserves might be affected in a manner that could reduce survivorship or reproductive success. This mitigation area will also partially overlap with an important migration area for gray whales. Summary of Mitigation The Navy's proposed mitigation measures are summarized in Tables 65 and 66. Summary of Procedural Mitigation A summary of procedural mitigation is described in Table 65 below. Table 65--Summary of Procedural Mitigation ------------------------------------------------------------------------ Summary of mitigation Stressor or activity requirements ------------------------------------------------------------------------ Environmental Awareness and Education.. Afloat Environmental Compliance Training program for applicable personnel. Active Sonar (depending on system)..... Depending on sonar source: 1,000 yd power down, 500 yd power down, and 200 yd shut down or 200 yd shut down. Air Guns............................... 150 yd. Pile Driving........................... 100 yd. Weapons Firing Noise................... 30 degrees on either side of the firing line out to 70 yd. Explosive Sonobuoys.................... 600 yd. Explosive Torpedoes.................... 2,100 yd. Explosive Medium-Caliber and Large- 1,000 yd (large-caliber Caliber Projectiles. projectiles); 600 yd (medium- caliber projectiles during surface-to-surface activities) or 200 yd (medium-caliber projectiles during air-to- surface activities). Explosive Missiles and Rockets......... 900 yd (0.6-20 lb net explosive weight) or 2,000 yd (21-500 lb net explosive weight). Explosive Bombs........................ 2,500 yd. Sinking Exercises...................... 2.5 nmi. Explosive Mine Countermeasure and 600 yd (0.1-5 lb net explosive Neutralization Activities. weight) or 2,100 yd (6-650 lb net explosive weight). Explosive Mine Neutralization 500 yd (0.1-20 lb net explosive Activities Involving Navy Divers. weight for positive control charges), or 1,000 yd (21-60 lb net explosive weight for positive control charges and all charges using time-delay fuses). Underwater Demolition Multiple Charge-- 700 yd. Mat Weave and Obstacle Loading. Maritime Security Operations--Anti- 200 yd. Swimmer Grenades. Vessel Movement........................ 500 yd (whales) or 200 yd (other marine mammals). Towed In-Water Devices................. 250 yd. Small-, Medium-, and Large-Caliber Non- 200 yd. Explosive Practice Munitions. Non-Explosive Missiles and Rockets..... 900 yd. Non-Explosive Bombs and Mine Shapes.... 1,000 yd. ------------------------------------------------------------------------ Summary of Mitigation Areas A summary of mitigation areas for marine mammals is described in Table 66 below. [[Page 29979]] Table 66--Summary of Mitigation Areas for Marine Mammals ------------------------------------------------------------------------ Mitigation area Summary of mitigation requirements ------------------------------------------------------------------------ Mitigation Areas for Marine Mammals ------------------------------------------------------------------------ Hawaii Island Mitigation Area The Navy would not exceed (Year-round). 300 hrs of mid-frequency active anti-submarine warfare sensor MF1 and 20 hrs of mid-frequency active anti-submarine warfare sensor MF4 per season annually. Should national security present a requirement to conduct additional training and testing using MF1 or MF4 in the mitigation area for national security, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated reports. The Navy will not use explosives \1\ during training or testing activities. Should national security present a requirement to use explosives, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. 4-Islands Region Mitigation Area The Navy will not use mid- (November 15-April 15). frequency active anti-submarine warfare sensor MF1 during training or testing activities. Should national security present a requirement to use MF1 during training or testing, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. San Diego Arc Mitigation Area The Navy would not exceed (June 1-October 31). 200 hrs of mid-frequency active anti-submarine warfare sensor MF1 (with the exception of active sonar maintenance and systems checks) annually within the area. Should national security present a requirement to conduct additional training and testing using MF1, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. The Navy will not use explosives during large-caliber gunnery, torpedo, bombing, and missile (including 2.75 in rockets) activities during training or testing activities. Should national security present a requirement to use these explosives during training or testing activities, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. Santa Barbara Island Mitigation The Navy will not use mid- Area (Year-round). frequency active anti-submarine warfare sensor MF1 and explosives in small-, medium-, and large- caliber gunnery; torpedo; bombing; and missile (including 2.75 in rockets) activities during unit- level training or major training exercises. Should national security present a requirement to use MF1 or these explosives during training or testing activities, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with advance notification and include the information in associated annual reports. ------------------------------------------------------------------------ Notes: \1\ Explosive restrictions within the Hawaii Island Mitigation Area apply only to those activities for which the Navy seeks MMPA authorization (e.g., surface-to-surface or air-to-surface missile and gunnery events, BOMBEX, and mine neutralization). Mitigation Conclusions NMFS has carefully evaluated the Navy's proposed mitigation measures--many of which were developed with NMFS's input during the previous phases of Navy training and testing authorizations--and considered a broad range of other measures (i.e., the measures considered but eliminated in the Navy's DEIS/OEIS, which reflect many of the comments that have arisen via NMFS or public input in past years) in the context of ensuring that NMFS prescribes the means of effecting the least practicable adverse impact on the affected marine mammal species and stocks and their habitat. Our evaluation of potential measures included consideration of the following factors in relation to one another: The manner in which, and the degree to which, the successful implementation of the mitigation measures is expected to reduce the likelihood and/or magnitude of adverse impacts to marine mammal species and stocks and their habitat; the proven or likely efficacy of the measures; and the practicability of the measures for applicant implementation, including consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. Based on our evaluation of the Navy's proposed measures, as well as other measures considered by the Navy and NMFS, NMFS has preliminarily determined that the Navy's proposed mitigation measures are adequate means of effecting the least practicable adverse impacts on marine mammals species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, while also considering personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. Additionally, the adaptive management component helps further ensure that mitigation is regularly assessed and opportunities are available to improve the mitigation, based on the factors above, through modification as appropriate. The proposed rule comment period provides the public an opportunity to submit recommendations, views, and/or concerns regarding the proposed mitigation measures. While NMFS has preliminarily determined that the Navy's proposed mitigation measures would effect the least practicable adverse impact on the affected species or stocks and their habitat, NMFS will consider all public comments to help inform our final decision. Consequently, the proposed mitigation measures may be refined, modified, removed, or added to prior to the issuance of any final rule based on public comments received, and where appropriate, further analysis of any additional mitigation measures. [[Page 29980]] Proposed Monitoring Section 101(a)(5)(A) of the MMPA states that in order to issue an ITA for an activity, NMFS must set forth ``requirements pertaining to the monitoring and reporting of such taking.'' The MMPA implementing regulations at 50 CFR 216.104(a)(13) indicate that requests for LOAs must include the suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species and of the level of taking or impacts on populations of marine mammals that are expected to be present. Although the Navy has been conducting research and monitoring in the HSTT Study Area for over 20 years, they developed a formal marine species monitoring program in support of the MMPA and ESA authorizations for the Hawaii and Southern California range complexes in 2009. This robust program has resulted in hundreds of technical reports and publications on marine mammals that have informed Navy and NMFS analysis in environmental planning documents, Rules and Biological Opinions. The reports are made available to the public on the Navy's marine species monitoring website (www.navymarinespeciesmonitoring.us) and the data on the Ocean Biogeographic Information System Spatial Ecological Analysis of Megavertebrate Populations (OBIS-SEAMAP) (www.seamap.env.duke.edu). The Navy would continue collecting monitoring data to inform our understanding of: The occurrence of marine mammals in the action area; the likely exposure of marine mammals to stressors of concern in the area; the response of marine mammals to exposures to stressors; the consequences of a particular marine mammal response to their individual fitness and, ultimately, populations; and, the effectiveness of implemented mitigation measures. Taken together, mitigation and monitoring comprise the Navy's integrated approach for reducing environmental impacts from the specified activities. The Navy's overall monitoring approach will seek to leverage and build on existing research efforts whenever possible. Consistent with the cooperating agency agreement between the Navy and NMFS, monitoring measures presented here, as well as the mitigation measures described above, focus on the protection and management of potentially affected marine mammals. A well-designed monitoring program can provide important feedback for validating assumptions made in analyses and allow for adaptive management of marine resources. Monitoring is required under the MMPA, and details of the monitoring program for the specified activities have been developed through coordination between NMFS and the Navy through the regulatory process for previous Navy at-sea training and testing actions. Input received during the public comment period and discussions with other agencies or NMFS offices during the rulemaking process could result in changes to the monitoring as described in this document. Integrated Comprehensive Monitoring Program (ICMP) The Navy's ICMP is intended to coordinate marine species monitoring efforts across all regions and to allocate the most appropriate level and type of effort for each range complex based on a set of standardized objectives, and in acknowledgement of regional expertise and resource availability. The ICMP is designed to be flexible, scalable, and adaptable through the adaptive management and strategic planning processes to periodically assess progress and reevaluate objectives. This process includes conducting an annual adaptive management review meeting, at which the Navy and NMFS jointly consider the prior-year goals, monitoring results, and related scientific advances to determine if monitoring plan modifications are warranted to more effectively address program goals. Although the ICMP does not specify actual monitoring field work or individual projects, it does establish a matrix of goals and objectives that have been developed in coordination with NMFS. As the ICMP is implemented through the Strategic Planning Process, detailed and specific studies will be developed which support the Navy's and NMFS top-level monitoring goals. In essence, the ICMP directs that monitoring activities relating to the effects of Navy training and testing activities on marine species should be designed to contribute towards one or more of the following top-level goals: An increase in understanding of the likely occurrence of marine mammals and/or ESA-listed marine species in the vicinity of the action (i.e., presence, abundance, distribution, and/or density of species); An increase in understanding of the nature, scope, or context of the likely exposure of marine mammals and/or ESA-listed species to any of the potential stressor(s) associated with the action (e.g., sound, explosive detonation, or military expended materials), through better understanding of one or more of the following: (1) The action and the environment in which it occurs (e.g., sound source characterization, propagation, and ambient noise levels); (2) the affected species (e.g., life history or dive patterns); (3) the likely co-occurrence of marine mammals and/or ESA-listed marine species with the action (in whole or part), and/or; (4) the likely biological or behavioral context of exposure to the stressor for the marine mammal and/or ESA-listed marine species (e.g., age class of exposed animals or known pupping, calving or feeding areas); An increase in understanding of how individual marine mammals or ESA-listed marine species respond (behaviorally or physiologically) to the specific stressors associated with the action (in specific contexts, where possible, e.g., at what distance or received level); An increase in understanding of how anticipated individual responses, to individual stressors or anticipated combinations of stressors, may impact either: (1) The long-term fitness and survival of an individual; or (2) the population, species, or stock (e.g., through effects on annual rates of recruitment or survival); An increase in understanding of the effectiveness of mitigation and monitoring measures; A better understanding and record of the manner in which the authorized entity complies with the ITA and Incidental Take Statement; An increase in the probability of detecting marine mammals (through improved technology or methods), both specifically within the mitigation zone (thus allowing for more effective implementation of the mitigation) and in general, to better achieve the above goals; and A reduction in the adverse impact of activities to the least practicable level, as defined in the MMPA. Strategic Planning Process for Marine Species Monitoring The Navy also developed the Strategic Planning Process for Marine Species Monitoring, which establishes the guidelines and processes necessary to develop, evaluate, and fund individual projects based on objective scientific study questions. The process uses an underlying framework designed around the ICMP's top-level goals, and a conceptual framework incorporating a progression of knowledge, spanning occurrence, exposure, response, and consequences. The Strategic Planning Process for Marine Species Monitoring is used to set overarching intermediate [[Page 29981]] scientific objectives, develop individual monitoring project concepts, identify potential species of interest at a regional scale, evaluate, prioritize and select specific monitoring projects to fund or continue supporting for a given fiscal year, execute and manage selected monitoring projects, and report and evaluate progress and results. This process addresses relative investments to different range complexes based on goals across all range complexes, and monitoring leverages multiple techniques for data acquisition and analysis whenever possible. The Strategic Planning Process for Marine Species Monitoring is also available online (