83 FR 29872 - 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
DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration
Federal Register Volume 83, Issue 123 (June 26, 2018)
Page Range
29872-30029
FR Document
2018-13115
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).
Federal Register, Volume 83 Issue 123 (Tuesday, June 26, 2018)
[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
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National Oceanic and Atmospheric Administration
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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]]
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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.
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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.
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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.
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Table 6 summarizes the proposed testing activities for the Naval
Sea Systems Command analyzed within the HSTT Study Area.
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Office of Naval Research
Table 7 summarizes the proposed testing activities for the Office
of Naval Research analyzed within the HSTT Study Area.
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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.
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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.
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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 (PN2) 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.
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\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\
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\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.
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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\
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\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).
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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.
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\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
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Procedural mitigation description
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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