80 FR 65183 - Endangered and Threatened Wildlife; 12-Month Finding on a Petition To Identify and Delist a Saint John River Distinct Population Segment of Shortnose Sturgeon Under the Endangered Species Act

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration

Federal Register Volume 80, Issue 206 (October 26, 2015)

Page Range		65183-65194
FR Document		2015-27148

We, NMFS, announce a 12-month finding on a petition to identify and ``delist'' shortnose sturgeon (Acipenser brevirostrum) within the Saint John River in New Brunswick, Canada under the Endangered Species Act (ESA). The shortnose sturgeon is currently listed as an endangered species, at the species level, under the ESA. Based on our review of the best scientific and commercial data available, we have determined that the population of shortnose sturgeon from the Saint John River does not qualify as a distinct population segment. Therefore, we did not consider the petition further, and we do not propose to delist this population.

Federal Register, Volume 80 Issue 206 (Monday, October 26, 2015)

[Federal Register Volume 80, Number 206 (Monday, October 26, 2015)]
[Proposed Rules]
[Pages 65183-65194]
From the Federal Register Online [www.thefederalregister.org]
[FR Doc No: 2015-27148]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 224

[Docket No. 150209121-5941-02]
RIN 0648-XD760

Endangered and Threatened Wildlife; 12-Month Finding on a
Petition To Identify and Delist a Saint John River Distinct Population
Segment of Shortnose Sturgeon Under the Endangered Species Act

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Department of Commerce.

[[Page 65184]]

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, NMFS, announce a 12-month finding on a petition to
identify and ``delist'' shortnose sturgeon (Acipenser brevirostrum)
within the Saint John River in New Brunswick, Canada under the
Endangered Species Act (ESA). The shortnose sturgeon is currently
listed as an endangered species, at the species level, under the ESA.
Based on our review of the best scientific and commercial data
available, we have determined that the population of shortnose sturgeon
from the Saint John River does not qualify as a distinct population
segment. Therefore, we did not consider the petition further, and we do
not propose to delist this population.

DATES: This finding was made on October 26, 2015.

ADDRESSES: Information used to make this finding is available for
public inspection by appointment during normal business hours at NMFS,
Office of Protected Resources, 1315 East-West Highway, Silver Spring,
MD 20910. The petition and the list of the references used in making
this finding are also available on the NMFS Web site at:
www.nmfs.noaa.gov/pr/species/fish/shortnose-sturgeon.html.

FOR FURTHER INFORMATION CONTACT: Lisa Manning, Office of Protected
Resources, 301-427-8466; Stephania Bolden, Southeast Regional Office,
727-824-5312; Julie Crocker, Greater Atlantic Regional Office, 978-282-
8480.

SUPPLEMENTARY INFORMATION:

Background

On September 24, 2014, we received a petition from Dr. Michael J.
Dadswell, Dr. Matthew K. Litvak, and Mr. Jonathan Barry regarding the
population of shortnose sturgeon (Acipenser brevirostrum) native to the
Saint John River in New Brunswick, Canada. The petition requests that
we identify the Saint John River population of shortnose sturgeon as a
distinct population segment (DPS) and contemporaneously ``delist'' this
DPS by removing it from the species-wide listing under the Endangered
Species Act. On April 6, 2015, we published a positive finding
indicating that the petitioned action may be warranted and that we were
initiating a status review to consider the petition further (80 FR
18347).
The shortnose sturgeon was originally listed as an endangered
species throughout its range by the U.S. Fish and Wildlife Service
(USFWS) on March 11, 1967, under the Endangered Species Preservation
Act (ESPA, 32 FR 4001). Shortnose sturgeon remained on the endangered
species list when the U.S. Congress replaced the ESPA by enacting the
Endangered Species Conservation Act of 1969, which was in turn replaced
by the Endangered Species Act of 1973 (ESA, 16 U.S.C. 1531 et seq.). We
subsequently assumed jurisdiction for shortnose sturgeon under a 1974
government reorganization plan (39 FR 41370, November 27, 1974). In
Canada, the shortnose sturgeon falls under the jurisdiction of the
Department of Fisheries and Oceans (DFO) and was first assessed by the
Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as
``Special Concern'' in 1980. This status was reconfirmed in 2005, and
the species was listed as Special Concern under the Canadian federal
Species at Risk Act (SARA) in 2009. The Special Concern status was
reconfirmed again in 2015 (COSEWIC, In Press). Shortnose sturgeon is
also listed under Appendix I of the Convention on International Trade
in Endangered Species of Wild Fauna (CITES).

Statutory, Regulatory and Policy Provisions

We are responsible for determining whether species are threatened
or endangered under the ESA (16 U.S.C. 1531 et seq.). To make this
determination, we first consider whether a group of organisms
constitutes a ``species'' under section 3 of the ESA, and then we
consider whether the status of the species qualifies it for listing as
either threatened or endangered. Section 3 of the ESA defines a
``species'' to include ``any subspecies of fish or wildlife or plants,
and any distinct population segment of any species of vertebrate fish
or wildlife which interbreeds when mature'' (16 U.S.C. 1532(16)). A
joint policy issued by NMFS and the U.S. Fish and Wildlife Service
(USFWS; collectively referred to as ``the Services'') clarifies the
interpretation of the phrase ``distinct population segment'' (DPS) for
the purposes of listing, delisting, and reclassifying a species under
the ESA (``DPS Policy,'' 61 FR 4722, February 7, 1996). The DPS Policy
identifies two criteria for determining whether a population is a DPS:
(1) The population must be ``discrete'' in relation to the remainder of
the taxon (species or subspecies) to which it belongs; and (2) the
population must be ``significant'' to the remainder of the taxon to
which it belongs.
Congress has instructed the Secretary to exercise the authority to
recognize DPS's ``sparingly and only when the biological evidence
indicates that such action is warranted'' (S. Rep. 96-151 (1979)). The
law is not settled as to the extent of the Services' discretion to
modify a species-level listing to recognize a DPS having a status that
differs from the original listing. In a recent decision, the United
States District Court for the District of Columbia held that the ESA
does not permit identification of a DPS solely for purposes of
delisting. Humane Soc'y v. Jewell, 76 F. Supp. 3d 69 (D.D.C. Dec. 19,
2014), appeal docketed, No. 15-5041 (D.C. Cir. Feb. 19, 2015) (Western
Great Lakes gray wolves) (consolidated with Nos. 15-5043, 15-5060, and
15-5061).
A species, subspecies, or DPS is ``endangered'' if it is in danger
of extinction throughout all or a significant portion of its range, and
``threatened'' if it is likely to become endangered within the
foreseeable future throughout all or a significant portion of its range
(ESA sections 3(6) and 3(20), respectively, 16 U.S.C. 1532(6) and
(20)). We interpret an ``endangered species'' to be one that is
presently in danger of extinction. A ``threatened species,'' on the
other hand, is not presently in danger of extinction, but is likely to
become so in the foreseeable future. In other words, the primary
statutory difference between a threatened and endangered species is the
timing of when a species may be in danger of extinction, either
presently (endangered) or in the foreseeable future (threatened). In
addition, we interpret ``foreseeable future'' as the horizon over which
predictions about the conservation status of the species can be
reasonably relied upon.
Pursuant to the ESA and our implementing regulations, the
determination of whether a species is threatened or endangered shall be
based on any one or a combination of the following five section 4(a)(1)
factors: The present or threatened destruction, modification, or
curtailment of habitat or range; overutilization for commercial,
recreational, scientific, or educational purposes; disease or
predation; inadequacy of existing regulatory mechanisms; and any other
natural or manmade factors affecting the species' existence. 16 U.S.C.
1533(a)(1); 50 CFR 424.11(c). Listing determinations must be based
solely on the best scientific and commercial data available, after
conducting a review of the species' status and after taking into
account any efforts being made by any state or foreign nation (or any
political subdivision of such state or foreign nation) to protect the
species. 16 U.S.C. 1532(b)(1)(A).

[[Page 65185]]

Under section 4(a)(1) of the ESA and the implementing regulations
at 50 CFR 424.11(d), a species shall be removed from the list if the
Secretary of Commerce determines, based on the best scientific and
commercial data available after conducting a review of the species'
status, that the species is no longer threatened or endangered because
of one or a combination of the section 4(a)(1) factors. The regulations
provide that a species listed under the ESA may be delisted only if
such data substantiate that it is neither endangered nor threatened for
one or more of the following reasons:

(1) Extinction. Unless all individuals of the listed species had
been previously identified and located, and were later found to be
extirpated from their previous range, a sufficient period of time
must be allowed before delisting to indicate clearly that the
species is extinct.
(2) Recovery. The principal goal of the USFWS and NMFS is to
return listed species to a point at which protection under the ESA
is no longer required. A species may be delisted on the basis of
recovery only if the best scientific and commercial data available
indicate that it is no longer endangered or threatened.
(3) Original data for classification in error. Subsequent
investigations may show that the best scientific or commercial data
available when the species was listed, or the interpretation of such
data, were in error.

50 CFR 424.11(d).

To complete the required finding in response to the current
delisting petition, we first evaluated whether the petitioned entity
meets the criteria of the DPS Policy. As we noted in our initial
petition finding, a determination whether to revise a species-level
listing to recognize one or more DPSs in place of a species-level
listing involves, first, determining whether particular DPS(s) exist(s)
(based on meeting the criteria of the DPS Policy) and, if that finding
is affirmative, complex evaluation as to the most appropriate approach
for managing the species in light of the purposes and authorities under
the ESA.

Species Description

Below, we summarize basic life history information for shortnose
sturgeon. A more thorough discussion of all life stages, reproductive
biology, habitat use, abundance estimates and threats are provided in
the Shortnose Sturgeon Biological Assessment completed by the Shortnose
Sturgeon Status Review Team in 2010 (SSRT 2010; http://www.fisheries.noaa.gov/pr/species/fish/shortnose-sturgeon.html).
There are 25 species and four recognized genera of sturgeons
(family Acipenseridae), which comprise an ancient and distinctive
assemblage with fossils dating to at least the Upper Cretaceous period,
more than 66 million years ago (Findeis 1997). The shortnose sturgeon,
Acipenser brevirostrum, is the smallest of the three extant sturgeon
species in eastern North America. Many primitive physical
characteristics that reflect the shortnose sturgeon's ancient lineage
have been retained, including a protective armor of bony plates called
``scutes''; a subterminal, protractile tube-like mouth; and
chemosensory barbels. The general body shape is cylindrical, tapering
at the head and caudal peduncle, and the upper lobe of the tail is
longer than the lower lobe. Shortnose sturgeon vary in color but are
generally dark brown to olive or black on the dorsal surface, lighter
along the row of lateral scutes, and nearly white on the ventral
surface. Adults have no teeth but possess bony plates in the esophagus
that are used to crush hard prey items (Vladykov and Greeley 1963;
Gilbert 1989). The skeleton is almost entirely cartilaginous with the
exception of some bones in the skull, jaw and pectoral girdle.
Shortnose sturgeon occur along the East Coast of North America in
rivers, estuaries, and marine waters. Historically, they were present
in most major rivers systems along the Atlantic coast (Kynard 1997).
Their current riverine distribution extends from the Saint John River,
New Brunswick, Canada, to possibly as far south as the St. Johns River,
Florida (Figure 1; Kynard 1997; Gorham and McAllister 1974). Recently
available information indicates that their marine range extends farther
northward than previously thought and includes the Minas Basin, Nova
Scotia (Dadswell et al. 2013). The distribution of shortnose sturgeon
across their range, however, is disjunct, with no known reproducing
populations occurring within the roughly 400 km of coast between the
Chesapeake Bay and the southern boundary of North Carolina. Shortnose
sturgeon live in close proximity with Atlantic sturgeon (Acipenser
oxyrinchus oxyrinchus) throughout much of their range. However,
Atlantic sturgeon spend more of their life cycle in the open ocean
compared to shortnose sturgeon. Within rivers, shortnose sturgeon and
Atlantic sturgeon may share foraging habitat and resources, but
shortnose sturgeon generally spawn farther upriver and earlier than
Atlantic sturgeon (Kynard 1997, Bain 1997).
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BILLING CODE 3510-22-C
Shortnose sturgeon typically migrate seasonally between upstream
freshwater spawning habitats and downstream foraging mesohaline (i.e.,
salinities of 5 to 18 parts per thousand) habitat based on water
temperature, flow, and salinity cues. Based on their varied and complex
use of freshwater, estuarine, and marine waters, shortnose sturgeon
have been characterized in the literature as ``anadromous'' or
``amphidromous'' (Bain 1977; Kieffer and Kynard 1993). An anadromous
species is defined as one that spawns in freshwater and spends much of
its life cycle in marine waters, whereas a freshwater amphidromous
species is one that spawns and remains in freshwater for most of its
life cycle but spends some time in saline water. Because shortnose
sturgeon had historically rarely been detected far from their natal
estuary, they were once considered to be largely confined to their
natal rivers and estuaries (NMFS 1998). However, more recent research
has demonstrated that shortnose sturgeon leave their natal estuaries,
undergo coastal migrations, and use other river systems to a greater
extent than previously thought (Kynard 1997; Savoy 2004; Fernandes
2010; Zydlewski et al. 2011; Dionne et al. 2013). The reasons for
inter-riverine movements are not yet clear, and the degree to which
this behavior occurs appears to vary among river systems.
Shortnose sturgeon are benthic feeders, and their diet typically
consists of small insects, crustaceans, mollusks, polychaetes, and
small benthic fishes (McCleave et al. 1977; Dadswell 1979;

[[Page 65187]]

Marchette and Smiley 1982; Dadswell et al. 1984; Moser and Ross 1995;
Kynard et al. 2000; Collins et al. 2002). Both juvenile and adult
shortnose sturgeon primarily forage over sandy-mud bottoms, which
support benthic invertebrates (Carlson and Simpson 1987, Kynard 1997).
Shortnose sturgeon have also been observed feeding off plant surfaces
(Dadswell et al. 1984). Sturgeon likely use electroreception,
olfaction, and tactile chemosensory cues to forage, while vision is
thought to play a minor role (Miller 2004).
Foraging in the colder rivers in the northern part of their range
appears to greatly decline or cease during winter months when shortnose
sturgeon generally become inactive. In mid-Atlantic areas, including
the Chesapeake Bay, and the Delaware River, foraging is believed to
occur year-round, though shortnose sturgeon are believed to feed less
in the winter (J. O'Herron, Amitrone O'Herron, Inc., pers. comm. 2008
as cited in SSRT 2010). In the southern part of their range, shortnose
sturgeon are known to forage widely throughout the estuary during the
winter, fall, and spring (Collins and Smith 1993, Weber et al. 1999).
During the hotter months of summer, foraging may taper off or cease as
shortnose sturgeon take refuge from high water temperatures.
Shortnose sturgeon are relatively small compared to most extant
sturgeon species and reach a maximum length of about 120 cm total
length (TL) and weight of about 24 kg (Dadswell 1979; Waldman et al.
2002); however, both maximum size and growth rate display a pattern of
gradual variation across the range, with the fastest growth rates and
smallest maximum sizes occurring in the more southern populations
(Dadswell et al. 1984). The northernmost populations exhibit the
slowest growth and largest adult sizes. The largest shortnose sturgeon
reported in the published literature to date was collected from the
Saint John River, Canada, and measured 143cm TL (122 cm fork length
(FL)) and weighed 23.6 kg (Dadswell 1979). In contrast, in their
review, Dadswell et al. (1984) indicated that the largest adult
reported from the St. Johns River, Florida, was a 73.5 cm (TL) female.
Dadswell et al. (1984) compared reported growth parameters across the
range and showed that the von Bertalanffy growth parameter K and
estimated asymptotic length ranged from 0.042 and 130.0 cm (FL),
respectively, for Saint John River fish to 0.149 and 97.0 cm (FL) for
Altamaha River, Georgia fish. However, the land-locked shortnose
sturgeon population located upstream of Holyoke Dam at river km 140 of
the Connecticut River has the slowest adult growth rate of any
surveyed, which may at least in part reflect food limitations (Taubert
1980a).
Shortnose sturgeon are relatively long-lived and slow to mature.
The oldest shortnose sturgeon reported was a 67 year-old female from
the Saint John River, and the oldest male reported was a 32 year-old
fish, also captured in the Saint John River (Dadswell 1979). In
general, fish in the northern portion of the species' range live longer
than individuals in the southern portion of the species' range (Gilbert
1989). Males and females mature at about the same length, around 45-55
cm FL, throughout their range (Dadswell et al. 1984). However, age at
maturity varies by sex and with latitude, with males in the southern
rivers displaying the youngest ages at maturity (see review in Dadswell
et al. 1984). For example, age at first maturation in males occurs at
about 2-3 years of age in Georgia and at about 10-11 years in the Saint
John River. Females mature by 6 years of age in Georgia and at about 13
years in the Saint John River (Dadswell et al. 1984).
Sturgeon are iteroparous, meaning they reproduce more than once
during their lifetime. In general, male shortnose sturgeon are thought
to spawn every other year, but they may spawn annually in some rivers
(Dovel et al. 1992; Kieffer and Kynard 1996). Females appear to spawn
less frequently--approximately every 3 to 5 years (Dadswell 1979).
Spawning typically occurs during late winter/early spring (southern
rivers) and mid-to-late spring (northern rivers) (Dadswell 1979,
Taubert 1980a and b, Kynard 1997). The onset of spawning may be cued by
decreasing river discharge following the peak spring freshet, when
water temperatures range from 8 to 15 [deg]C and bottom water
velocities range between 25-130 cm/s, although photoperiod (or day-
length) appears to control spawning readiness (Dadswell et al. 1984;
Kynard et al. 2012). Spawning appears to occur in the sturgeons' natal
river, often just below the fall line at the farthest accessible
upstream reach of the river (Dovel 1981; Buckley and Kynard 1985;
Kieffer and Kynard 1993; O`Herron et al. 1993; Kieffer and Kynard
1996). Following spawning, adult shortnose sturgeon disperse quickly
down river and typically remain downstream of their spawning areas
throughout the rest of the year (Buckley and Kynard 1985, Dadswell et
al. 1984; Buckley and Kynard 1985; O'Herron et al. 1993).
In a review by Gilbert (1989), fecundity of shortnose sturgeon was
reported to range between approximately 30,000-200,000 eggs per female.
Shortnose sturgeon collected from the Saint John River had a range of
27,000-208,000 eggs and a mean of 11,568 eggs/kg body weight (Dadswell
1979). Development of the eggs and transition through the subsequent
larval, juvenile and sub-adult life stages are discussed in more detail
in SSRT 2010.
A total abundance estimate for shortnose sturgeon is not available.
However, population estimates, using a variety of techniques, have been
generated for many individual river systems. In general, northern
shortnose sturgeon population abundances are greater than southern
populations (Kynard 1997). The Hudson River shortnose sturgeon
population is currently considered to be the largest extant population
(61,000 adults, 95 percent CI: 52,898-72,191; Bain et al. 2007;
however, see discussion of this estimate in SSRT 2010). Available data
suggest that some populations in northern rivers have increased over
the past several decades (e.g., Hudson, Kennebec; Bain et al. 2000;
Squiers 2003) and that others may be stable (e.g., Delaware; Brundage
and O'Herron 2006). South of Chesapeake Bay, populations are relatively
small compared to the northern populations. The largest population of
shortnose sturgeon in the southern part of the range is from the
Altamaha River, which was most recently estimated at 6,320 fish (95%
CI: 4387-9249; Devries 2006). Occasional observations of shortnose
sturgeon have been made in some rivers where shortnose sturgeon are
considered extirpated (e.g., St. Johns, St. Mary's, Potomac,
Housatonic, and Neuse rivers); the few fish that have been observed in
these rivers are generally presumed to be immigrants from neighboring
basins.
The most recent total population estimate for the Saint John River
dates to the 1970's. Using tag recapture data from 1973-1977, Dadswell
(1979) calculated a Jolly-Seber population estimate of 18,000 (30% SE; 95 percent CI: 7,200-28,880, COSEWIC, In Press) adults (>
50 cm) below the Mactaquac Dam. Several partial population estimates
are also available for the Kennebecasis River, a tributary in the lower
reaches of the Saint John River. Litvak (unpublished data) calculated a
Jolly-Seber estimate of 2,068 fish (95% CI: 801-11,277) in the
Kennebecasis using mark-recapture data from 1998 to 2004 (COSEWIC, In
Press). Based on videotaping of overwintering aggregations of shortnose
sturgeon on the Kennebecasis River at the confluence of the Hammond
River (rkm 35), Li et al. (2007) used ordinary Kriging to estimate that
4,836 (95% CI:

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4,701-4,971) adult shortnose sturgeon were overwintering in that area.
Usvyatsov et al. (2012) repeated this sampling in 2009 and 2011 and,
using three different modeling techniques, estimated a total of 3,852-
5,222 shortnose sturgeon in the study area, which suggests fairly
stable abundance and habitat use at this site.
Threats that contributed to the species' decline and led to the
listing of shortnose sturgeon under the ESA included pollution,
overfishing, and bycatch in the shad fishery (USDOI 1973). Shortnose
sturgeon were also thought to be extirpated, or nearly so, from most of
the rivers in their historical range (USDOI 1973). In the late
nineteenth and early twentieth centuries, shortnose sturgeon were
commonly harvested incidental to Atlantic sturgeon, the larger and more
commercially valuable of these two sympatric sturgeon species (NMFS
1998). Although there is currently no legal directed fishing for
shortnose sturgeon in the United States, poaching is suspected, and
bycatch still occurs in some areas. In particular, shortnose sturgeon
are caught incidentally by bass anglers and in the alewife/gaspereau,
American shad, American eel, and Atlantic sturgeon fisheries in the
Saint John River; and shad fisheries in the Altamaha River, Santee
River, Savannah River, and elsewhere (COSEWIC, In Press; SSRT 2010;
Bahn et al. 2009; COSEWIC 2005). The construction of dams has also
resulted in substantial loss of historical shortnose sturgeon habitat
in some areas along the Atlantic seaboard. The construction and
operation of dams can impede upstream movement to sturgeon spawning
habitat (e.g., Connecticut River, Santee River). Remediation measures,
such as dam removal or modification to allow for fish passage have
improved access in some rivers, and additional similar restoration
efforts are being considered in other areas (e.g., possible removal of
the Mactaquac dam in the Saint John River). Other possible and ongoing
threats include operation of power generating stations, water diversion
projects, dredging, and other in-water activities that impact habitat.

Distinct Population Segment Analysis

The following sections provide our analysis of whether the
petitioned entity--the Saint John River population of shortnose
sturgeon--qualifies as a DPS of shortnose sturgeon (whether it is both
``discrete'' and ``significant''). To complete this analysis we relied
on the best scientific and commercial data available and considered all
relevant literature and public comments submitted in response to our
90-day finding (80 FR 18347, April 6, 2015).
For purposes of this analysis, we defined the Saint John River
population segment of shortnose sturgeon to consist of shortnose
sturgeon spawned in the Saint John River downstream of the Mactaquac
Dam. Prior to construction of Mactaquac Dam in 1968/1969, sturgeon
occurred upstream of the dam; however, it is unclear whether these were
shortnose and/or Atlantic sturgeon and whether any sturgeon are still
present upstream of the dam (COSEWIC, In Press). Lacking this
information, we cannot consider fish that may be present upstream of
the dam in our distinct population segment analysis. Throughout our
discussion below we also use the term ``population'' to refer
collectively to all shortnose sturgeon that are presumed to be natal to
a particular river rather than using this term to refer strictly to a
completely closed reproductive unit.

Discreteness Criterion

The Services' joint DPS Policy states that a population segment of
a vertebrate species may be considered discrete if it satisfies either
one of the following conditions:
(1) It is markedly separated from other populations of the same
taxon as a consequence of physical, physiological, ecological, or
behavioral factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation.
(2) It is delimited by international governmental boundaries within
which differences in control of exploitation, management of habitat,
conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the ESA (61 FR 4722,
February 7, 1996).
There are no physical barriers preventing the movement of Saint
John River shortnose sturgeon outside of the Saint John River estuary
or along the coast. The Mactaquac Dam, located about 140 km upstream
and at the head of tide (Canadian Rivers Institute 2011), is the first
upstream physical barrier on the Saint John River. This and other dams
on the Saint John River block shortnose sturgeon from accessing
upstream habitats, but there are no dams or other physical barriers
separating Saint John River sturgeon from other shortnose sturgeon
populations.
As mentioned previously, shortnose sturgeon have been documented to
leave their natal river/estuary and move to other rivers to varying
extents across their range. For example, telemetry data generated by
Zydlewski et al. (2011) during 2008-2010 indicate that inter-riverine
movements of adult shortnose sturgeon occur fairly frequently among
rivers in Maine. Seventy percent of tagged adults (25 of 41 fish) moved
between the Penobscot and Kennebec rivers (about 150 km away), and up
to 52% of the coastal migrants (13 of 25 fish) also used other, smaller
river systems (i.e., Damariscotta, Medomak, St. George) between the
Penobscot and Kennebec rivers (Zydlewski et al. 2011). Shortnose
sturgeon are also known to move between rivers in Maine and (e.g.,
Kennebec, Saco) and the Merrimack River estuary in Massachusetts,
traveling distances of up to about 250 km (as measured by a
conservative, direct path distance; Little et al. 2013; Wippelhauser et
al. 2015). At the other end of the range, in the Southeast United
States, inter-riverine movements appear fairly common and include
movements between the Savannah River and Winyah Bay and between the
Altamaha and Ogeechee rivers (Peterson and Farrae 2011; Post et al.
2014).
Many inter-riverine movements have been observed elsewhere within
the species' range, but patterns are not yet well resolved. For
example, some shortnose sturgeon captured and/or tagged in the
Connecticut River have been recaptured, detected, or were previously
tagged in the Housatonic River (T. Savoy, CT DEP, pers. comm. 2015),
the Hudson River (Savoy 2004), and the Merrimack River (M. Kieffer,
USGS, pers. comm. 2015). At this time, the available tagging and
tracking information is too limited to determine if Hudson River and
Connecticut River shortnose sturgeon are making regular movements
outside of their natal rivers and whether movement as far as the
Merrimack River is a normal behavior. Movement data from the Chesapeake
Bay is also relatively limited, but existing data indicate that
shortnose sturgeon do move from the Chesapeake Bay through the
Chesapeake and Delaware Canal into the Delaware River (Welsh et al.
2002).
The distances of the reported marine migrations vary widely from
very short distances--such as between the Santee River and Winyah Bay,
which are only about 15 km apart--to fairly long--as in the case of
movements between the Merrimack and the Penobscot rivers, which are
about 339 km apart at their mouths.\1\ In general, the available data

[[Page 65189]]

suggest that movements between geographically proximate rivers are more
common, while movements between more distant rivers do not, or only
rarely, occur. A detailed discussion of the physical movements of
shortnose sturgeon is provided in SSRT 2010.
---------------------------------------------------------------------------

\1\ Distances between rivers mouths reported here were measured
in GIS using the NOAA Medium Resolution Vector Shoreline, 20m
bathymetry contour, and a fixed scale of 1:250,000. Estimated
distances reported are the average of three, independently drawn and
measured paths for each river pair. The assumed travel path between
river mouths was the shortest possible distance that followed the
general outline of the coast and was constrained by the 20m
bathymetry contour, except where the shortest travel path across a
deep, narrow inlet or bay crossed the 20m bathymetry contour.
---------------------------------------------------------------------------

The extent of coastal movements of shortnose sturgeon from the
Saint John River is currently unknown (COSEWIC, In Press); however,
some limited data are available and provide some insight into whether
these fish may be geographically isolated from other populations. Any
movement between Saint John River sturgeon and the nearest population
in the Penobscot River would require a marine migration of about 362
km, a similar travel distance as between the Merrimack and the
Penobscot rivers (340 km) and between the Connecticut and Merrimack
rivers (348 km).\2\ Dadswell (1979) reported that of 121 marked Saint
John River shortnose sturgeon recaptured by commercial fisherman, 13
fish (11 percent) were recaptured in the Bay of Fundy, indicating that
a portion of the population migrated into the marine environment. In
addition, a confirmed shortnose sturgeon was caught in a fishing weir
in the Minas Basin, off the coast of Nova Scotia about 165 km north of
the mouth of the Saint John River (Dadswell et al. 2013). Fishermen in
the Minas Basin also claim to catch about one to two shortnose sturgeon
per year in their weirs (Dadswell et al. 2013). While it is plausible
that the shortnose sturgeon captured in the Minas Bay originated from
the Saint John River, data to confirm this are not available. In
contrast, limited telemetry data suggest that movements outside of the
Saint John River are not common. Of 64 shortnose sturgeon tagged in the
Saint John River over the course of about 16 years from 1999 to 2015,
none have been detected moving past the farthest downriver acoustic
receiver located near the Saint John Harbor Bridge (M. Litvak, pers.
comm. July 31, 2015).
---------------------------------------------------------------------------

\2\ Distances reported here were measured following the same
methods described in the previous footnote. The distance reported
between the Connecticut and Merrimack River assumes a travel path
via the Cape Cod Canal. A travel path around Cape Cod would instead
result in a marine migration of about 560 km.
---------------------------------------------------------------------------

Overall, while there is unambiguous evidence that shortnose
sturgeon from the Saint John River leave the estuary--at least
occasionally--and use the marine environment, and that shortnose
sturgeon are capable of making long distance movements between river
systems, there are no available data on coastal migrations of Saint
John River shortnose sturgeon. To date, there are also no reported
observations or detections of shortnose sturgeon from the Gulf of Maine
rivers moving into the Saint John River. Thus, while it is possible
that the Saint John River shortnose sturgeon come in contact with
shortnose sturgeon from elsewhere, it is also likely that some degree
of geographical isolation by distance is occurring.
Although acoustic telemetry studies have revealed that shortnose
sturgeon leave their natal river systems to a much greater extent than
previously thought, such movements do not necessarily constitute
permanent emigration or indicate interbreeding of populations. Tagging
and telemetry studies within several river systems have provided
evidence that shortnose sturgeon in those particular systems tend to
spawn in their natal river (e.g., Dovel 1981; Buckley and Kynard 1985;
Kieffer and Kynard 1993; O`Herron et al. 1993; Kieffer and Kynard
1996). Tag return data for shortnose sturgeon in the Saint John River
over the course of a 4-year study completed by Dadswell (1979) suggests
there is little emigration from this system as well, and that spawning
takes place in the freshwater sections of the upper estuary. The high
site fidelity to natal rivers suggested by this and other studies
indicates a there is a possible behavioral mechanism for the marked
separation of the Saint John River population of shortnose sturgeon
from other populations of the species.
A substantial amount of genetic data has become available since the
``Final Recovery Plan for Shortnose Sturgeon'' was developed in 1998.
Below, we summarize the best available genetic data and information,
which informed our evaluation of the ``discreteness'' of the Saint John
River population segment. A more in-depth presentation of genetic data,
including discussions of types of analyses and assumptions, is
available in the Biological Assessment (SSRT 2010).
Much of the published information on population structure for
shortnose sturgeon has been based on the genetic analysis of the
maternally inherited mitochondrial DNA (mtDNA) due in part to the
difficulties of analyzing data from the polyploid nuclear genome
(Waldman et al. 2008). The analyses have focused on a moderately
polymorphic 440 base pair portion of the mtDNA control region--a
relatively rapidly evolving region of mtDNA and thus a good indicator
of population-level differentiation. Haplotype frequencies and sequence
divergence data have consistently indicated an overall isolation-by-
distance pattern of genetic population structure across the species'
range, meaning that populations of shortnose sturgeon inhabiting rivers
and embayments that are geographically more distant tend to be less
related than those that are geographically closer (e.g., Walsh et al.
2001, Grunwald et al. 2002, Waldman et al. 2002, and Wirgin et al.
2005; Wirgin et al. 2009). The haplotypes observed are typically shared
across two to four or more adjacent sampled rivers but with little
sharing of haplotypes between northern and southern populations
(Waldman et al. 2002; Wirgin et al. 2009). Results for the Saint John
River are compatible with these general patterns. For example, in the
largest study to date, Wirgin et al. (2009) observed eight haplotypes
within the Saint John River sample (n=42); and of the eight observed
haplotypes, one was exclusive (or ``private'') to the Saint John River
(and observed in 1 of 42 fish), and the remaining haplotypes were
shared with two to six other rivers. None of the shared haplotypes were
observed in samples south of the Chesapeake Bay. A previously
unreported haplotype was recently observed in 2 of 15 shortnose caught
from the Kennebecasis River, a tributary of the Saint John (Kerr, 2015;
P. Wilson, public comment, May 2015). This new haplotype could indicate
an even greater degree of differentiation of the Saint John River fish;
however, no other rivers were sampled or analyzed as part of this
study.
Despite the localized sharing of haplotypes, frequencies of the
observed haplotypes are significantly different in most pairwise
comparisons of the rivers sampled (i.e., comparisons of haplotype
frequencies from samples from two rivers), including many adjacent
rivers (Wirgin et al. 2009). Such pairwise comparisons for the Saint
John River in particular have indicated that this population is
genetically distinct from the geographically closest sampled
populations, including the Penobscot, Kennebec, and Androscoggin rivers
(Grunwald et al. 2002; Waldman et al. 2002; Wirgin et al. 2005; Wirgin
et al. 2009). For example, Wirgin et al. (2009) reported significant
differences (p<0.0005) in haplotype frequencies between Saint John
River shortnose sturgeon (n=42) and Penobscot (n=44, Chi-square=37.22),
Kennebec (n=54, Chi-square=54.85), and Androscoggin (n=48, Chi-
square=37.91) river samples. The level of genetic differentiation
between the Saint John River population and the Penobscot, Kennebec,
and

[[Page 65190]]

Androscoggin rivers also appears substantial, with Phi ST
values ranging from 0.213 to 0.291 (where Phi ST ranges from
0 to 1, with 1 indicating complete isolation; Wirgin et al. 2009).
Estimates of female-mediated gene flow between the Saint John River
and the Gulf of Maine rivers are fairly low. Wirgin et al. (2009)
estimated female-mediated gene flow between the Saint John River and
other Gulf of Maine rivers as 1.90-2.85 female migrants per generation
based on Phi ST values, and as 1.5-1.9 females per
generation in a separate, coalescent-based analysis. This result
suggests that (if model assumptions are true) no more than three female
shortnose sturgeon from the Saint John River are likely to spawn in the
other Gulf of Maine rivers (or vice versa) per generation. These
results provide additional evidence that the degree of female-based
reproductive exchange between the Saint John River population and other
nearby shortnose river populations has been relatively limited over
many generations.
More recently, King et al. (2014) completed a series of analyses
using nuclear DNA (nDNA) samples from 17 extant shortnose sturgeon
populations across the species range. In contrast to the maternally
inherited mtDNA, nDNA reflects the genetic inheritance from both the
male and female parents. King et al. (2014) surveyed the samples at 11
polysomic microsatellite DNA loci and then evaluated the 181 observed
alleles as presence/absence data using a variety of analytical
techniques. The population structuring revealed by these analyses is
consistent with the previous mtDNA analyses in that they also indicate
a regional scale isolation-by-distance pattern of genetic
differentiation. Analysis of genetic distances among individual fish
(using principle coordinate analysis, PCO) revealed that the sampled
fish grouped into one of three major geographic units: (1) Northeast,
which included samples from the Saint John, Penobscot, Kennebec,
Androscoggin, and Merrimack rivers; (2) Mid-Atlantic, which included
samples from the Connecticut, Hudson, and Delaware rivers, as well as
the Chesapeake Bay proper; and (3) Southeast, which included samples
from the Cape Fear River, Winyah Bay, the Santee-Cooper, Edisto,
Savannah, Ogeechee, and Altamaha rivers, and Lake Marion (King et al.
2014).
Subsequent analyses revealed that each of the three regions has a
different pattern of sub-structuring. Within the Northeast group, two
separate analyses (PCO and STRUCTURE) indicated a high degree of
relatedness and possible panmixia (i.e., random mating of individuals)
among the Penobscot, Kennebec, and Androscoggin rivers; whereas, the
Saint John and Merrimack rivers appeared more differentiated from each
other as well as from the other Gulf of Maine rivers (King et al.
2014). Pairwise comparisons at the population level showed that, within
the Northeast region, estimates of genetic differentiation were
greatest between the Saint John and Merrimack rivers (Phi PT
= 0.100, p <0.0004), the two most distant rivers within this region.
Pairwise comparisons of the Saint John River to the remaining rivers
within the Northeast region revealed lower but still statistically
significant levels of genetic differentiation (Phi PT =
0.068-0.077; King et al. 2014). Relatively low levels of
differentiation were observed in pairwise comparisons for all other
rivers within the Northeast region (Phi PT = 0.013-0.087),
half of which were not statistically significant (King et al. 2014). In
comparison, within the Mid-Atlantic group, pairwise comparisons among
rivers showed moderate levels of genetic differentiation among most
river populations (average Phi PT = 0.077, range = 0.018-
0.118); whereas, estimates of population level genetic differentiation
were very low among samples populations in the Southeast group (average
Phi PT = 0.047, range = 0.005 to 0.095; King et al. 2014),
suggesting a more genetically similar set of populations.
Theoretical estimates of gene flow (derived from Phi PT
values) between the Saint John River and the other Northeast rivers
ranged from 2.25 to 3.43 migrants per generation (King et al. 2014).
Gene flow estimates for the Merrimack River were similarly low, ranging
from 2.25 to 4.06 (King et al. 2014). In contrast, the effective number
of migrants per generation estimated to occur between the remaining
rivers within the Northeast region was much higher and ranged from
16.42 to 83.08 (King et al. 2014).
Overall, the analyses completed by King et al. (2014) indicate that
differentiation among Northeast populations is less than that observed
among the Mid-Atlantic populations and greater than that observed among
Southeast populations. However, within the Northeast region, both the
Saint John and Merrimack River sample populations are genetically
distinct from the other sample populations. Although the estimates of
gene flow suggest some connectivity between the Saint John and other
rivers within the Northeast, the significantly different allele and
haplotype frequencies shown consistently in the nDNA and mtDNA studies
provide indirect evidence that the Saint John River population is
relatively reproductively isolated.
As highlighted in the DPS Policy, quantitative measures of
morphological discontinuity or differentiation can serve as evidence of
marked separation of populations. We examined whether the morphological
data for shortnose sturgeon across its range provide evidence of marked
separation of the Saint John River population. As noted previously,
maximum adult size (length and weight) varies across the range, with
the largest maximum sizes occurring in the Saint John River at the
northernmost end of the range, and the smallest sizes occurring in
rivers at the southern end of the range (Dadswell et al. 1984). The
largest individual reported in the literature (122 cm FL, 23.6 kg) was
captured in the Saint John River, although there is also a report of a
specimen measuring 124.6 cm FL (M. Litvak, unpublished data, as cited
in COSEWIC, In Press). Lengths of shortnose sturgeon captured in
surveys of the Saint John River in 1974-1975 ranged from 60 to 120 cm
FL (n=1,621). The majority of these fish, however, were smaller than
100 cm FL (1,476 fish), and only six fish were longer than 111 cm FL
(Dadswell 1979). To the south, in the Kennebec River, Maine shortnose
sturgeon captured during 1980 and 1981 had lengths ranging from 58.5 to
103.0 cm FL, and averaging 80.8 cm FL (n=24; Walsh et al. 2001).
Smaller size ranges are reported for rivers in the southernmost portion
of the range with some occasional captures of larger specimens. For
example, adult shortnose sturgeon captured in the Altamaha River,
Georgia, in 2010-2013 ranged from 57.4-83.0 cm FL and averaged 70.1 cm
long (FL, n=40; Peterson 2014), but a shortnose sturgeon measuring
104.5 cm FL and weighing 8.94 kg was captured in the Altamaha River in
summer, 2004 (D. Peterson, UGA, unpubl. data). Overall, the attribute
of size appears to display clinal variation, meaning there is a gradual
change with geographic location (Huxley 1938). The fact that the Saint
John River population segment, which lies at the northernmost end of
the range, exhibits the largest sizes does not in itself constitute a
morphological discontinuity. Given the apparent gradual nature of the
variation in size with latitude, we find that there is no marked
separation of the Saint John River population segment on the basis of a
quantitative discontinuity in size.
In addition to body size, other attributes such as snout length,
head length, and mouth width can provide evidence of a morphological

[[Page 65191]]

discontinuity and were also considered. Walsh et al. (2001) examined
six morphological and five meristic attributes for shortnose sturgeon
in the Androscoggin, Kennebec, and Hudson rivers. All morphological
features measured (i.e., body length, snout length, head length, mouth
width, and interorbital width) were largest for the Kennebec River fish
and smallest for fish from the southern-most river in the study, the
Hudson River (Walsh et al. 2001). Meristic features (e.g., scute
counts) were similar for the three rivers and were not related to fish
size (Walsh et al. 2001). Overall, the degree of phenotypic
differentiation of fish from the two rivers in Maine (Androscoggin and
Kennebec), which share an estuary mouth, was very low, while a much
greater degree of differentiation was observed for the fish from the
Hudson River (Walsh et al. 2001). This result was congruent with
results of corresponding mtDNA analyses, which indicated that the
Hudson River had a much greater degree of genetic differentiation from,
and much lower rate of gene flow with, the two rivers in Maine (Walsh
et al. 2001). The results of this particular study suggest there could
be clinal variation in these other phenotypic characteristics, similar
to the pattern observed for body size. As far as we are aware, however,
similar studies have not yet been conducted to examine the variation in
additional sets of morphological attributes across the range of
shortnose sturgeon and relative to the Saint John River population in
particular. Therefore, there is no basis to conclude marked separation
of the Saint John River population segment on the basis of
morphological discontinuity.
In conclusion, although the currently available data do not show
that the Saint John River shortnose sturgeon constitute a completely
isolated or closed population, we find that available genetic data,
evidence of site fidelity, and the likelihood of some degree of
geographical isolation together constitute sufficient information to
indicate that the Saint John River shortnose sturgeon are markedly
separated from other populations of shortnose sturgeon. Thus, after
considering the best available data and all public comments submitted
in response to our initial petition finding, we conclude that the Saint
John River population segment of shortnose sturgeon is ``discrete.'' We
therefore proceeded to evaluate the best available data with respect to
the second criterion of the DPS Policy, ``significance.''

Significance Criterion

Under the DPS Policy, if a population segment is found to be
discrete, then we proceed to the next step of evaluating its biological
and ecological significance to the taxon to which it belongs. As we
explained above, a population must be both ``discrete'' (the first
prong of the DPS Policy) and ``significant'' (the second prong of the
DPS Policy) to qualify for recognition as a DPS.
Consideration of significance may include, but is not limited to:
(1) Persistence of the discrete population segment in an ecological
setting unusual or unique for the taxon; (2) evidence that the loss of
the discrete population segment would result in a significant gap in
the range of a taxon; (3) evidence that the discrete population segment
represents the only surviving natural occurrence of a taxon that may be
more abundant elsewhere as an introduced population outside its
historical range; and (4) evidence that the discrete population segment
differs markedly from other populations of the species in its genetic
characteristics (61 FR 4722, February 7, 1996). These four factors are
non-exclusive; other relevant factors may be considered in the
``significance'' analysis. Further, significance of the discrete
population segment is not necessarily determined by existence of one of
these classes of information standing alone. Rather, information
analyzed under these and any other applicable considerations is
evaluated relative to the biological and ecological importance of the
discrete population to the taxon as a whole. Accordingly, all relevant
and available biological and ecological information is analyzed to
determine whether, because of its particular characteristics, the
population is significant to the conservation of the taxon as a whole.

Persistence in an Ecological Setting Unusual or Unique for the Taxon

Shortnose sturgeon once occupied most major rivers systems along
the Atlantic coast of North America (Kynard 1997). Although extirpated
from some areas due mainly to overharvest, bycatch, pollution, and
habitat degradation, shortnose sturgeon still occur in at least 25
rivers systems within their historical range (NMFS 1998). Throughout
their current range, shortnose sturgeon occur in riverine, estuarine,
and marine habitats; and, as adults, generally move seasonally between
freshwater spawning habitat and downstream mesohaline and sometimes
coastal marine areas in response to cues such as water temperature,
flow, and salinity. Like other species of sturgeon (e.g. A.
transmontanus in the Columbia River, Oregon), shortnose sturgeon are
also capable of adopting a fully freshwater existence, as is the case
for the population of shortnose sturgeon above the Holyoke Dam in the
Connecticut River and in Lake Marion, South Carolina. While each river
system within the shortnose sturgeon's range is similar in terms of its
most basic features and functions, each river system differs to varying
degrees in terms of its specific, physical and biological attributes,
such as hydrologic regime, benthic substrates, water quality, and prey
communities. A few examples are discussed briefly below.
The Saint John River begins in northern Maine, United States,
travels through New Brunswick, Canada, and empties into the Bay of
Fundy within the northeast Gulf of Maine. The river is approximately
673 km long, fed by numerous tributaries, and has a large tidal estuary
and a basin area of over 55,000 km\2\ (Kidd et al. 2011). According to
the Nature Conservancy's (TNC) ecoregion classification system, the
Saint John River watershed lies within the New England-Acadian
(terrestrial), Northeast United States and Southeast Canada Atlantic
Drainages (freshwater), and the Gulf of Maine/Bay of Fundy (marine)
ecoregions. The mean annual discharge is approximately 1,100 m\3\/s,
dissolved oxygen levels average 8.5 to 11 mg/l, and benthic substrates
downstream of the Mataquac Dam consist largely of shifting sands (Kidd
et al. 2011). Due to the low slope of the lower reaches and the extreme
tidal range of the Bay of Fundy, the head of the tide can extend about
140 km upstream from the river mouth (Kidd et al. 2011). During the
shortnose sturgeon spring/summer spawning season, water temperatures
range from about 10 to 15 [deg]C; and within overwintering areas, water
temperature range between 0 and 13 C (Dadswell 1979; Dadswell et al.
1984). Shortnose sturgeon in the Saint John River appear to move to
deeper waters when surface water temperatures exceed 21 [deg]C
(Dadswell et al. 1984). Further to the south, but still within the same
terrestrial, freshwater, and marine TNC ecoregions as the Saint John
River, is the smaller Penobscot River system in Maine. This river is
175 km long (not including the West and South Branches), has a drainage
basin of 22,265 km\2\, and an annual average discharge of about 342
m\3\/s (Lake et al. 2012; USGS 2015). Benthic substrates, consisting of
bedrock, boulders, cobble and sand deposits are undergoing changes in
response to the removal of

[[Page 65192]]

two dams--Great Works Dam at rkm 60 and Veazie Dam at rkm 48--within
the past three years (FERC 2010; Cox et al. 2014). The Veazie Dam was
located close to the head of the tide, and although conditions have
since changed, Haefner (1967, as cited in Fernandes et al. 2010) stated
that, during peak springtime flows, freshwater extends to rkm 17, and
that the salt wedge intrudes as far as about rkm 42 when river
discharges decrease in summer. Water temperatures in shortnose sturgeon
overwintering areas in the Penobscot River range from about 0 [deg]C to
13.3 [deg]C, and the fish appear to move out of overwintering areas
when water temperatures reach about 2.4 [deg]C (Fernandes et al. 2010).
Towards the southern end of the range and occurring within a very
different set of ecoregions is the Altamaha River, which is formed by
the confluence of the Ocmulgee and Oconee rivers in Georgia. One of the
longest free-flowing systems on the Atlantic Coast, the Atlamaha River
is just over 220 km long, has a watershed area of about 37,300 km\2\,
and flows mainly eastward before emptying into the Atlantic Ocean (TNC
2005). Tidal influence extends up to about rkm 40 (DeVries 2006). The
average annual discharge is 381 m\3\/s, and benthic substrates consist
mostly of sands with very few rocky outcrops (Heidt and Gilbert 1979;
DeVries 2006). Water temperatures during the winter/spring spawning
period have averaged about 10.5 [deg]C (Heidt and Gilbert 1979), which
is consistent with DeVries' (2006) observation that spawning runs
appeared to commence when water temperatures reach 10.2 [deg]C. When
water temperatures exceed 27 [deg]C, shortnose sturgeon typically move
above the salt-fresh water interface and aggregate in deeper areas of
the river (DeVries 2006); however, shortnose sturgeon have also been
observed to use lower portions of the river throughout the summer, even
when water temperatures averaged 34 [deg]C (Heidt and Gilbert 1979;
DeVries 2006).
Overall, the variation in habitat characteristics across the range
of shortnose sturgeon indicates that there is no single type or typical
river system. Despite a suite of existing threats, shortnose sturgeon
continue to occupy many river systems across their historical range.
The fact that the Saint John River lies at one end of the species'
range, and among other attributes, experiences different temperature
and flow regimes, does not mean that this particular river is unusual
or unique given the variability in habitat conditions observed across
the range. Therefore, we conclude that the Saint John River is not an
unusual or unique ecological setting when viewed against the range of
the taxon as a whole. Furthermore, though not relied up on for our
finding, we note that COSEWIC (In Press) recently concluded that
shortnose sturgeon from other river systems would probably be able to
survive in Canada.

Significant Gap in the Range of the Taxon

The second consideration under the DPS Policy in determining
whether a population may be ``significant'' to its taxon is whether the
``loss of the discrete population segment would result in a significant
gap in the range of a taxon'' (61 FR 4722, February 7, 1996). Shortnose
sturgeon are distributed along the Atlantic coast of North America from
the Minas Basin, Nova Scotia to the St. Johns River, Florida,
representing a coastal range of roughly 3,700 km. The Saint John River,
located at the northern end of the range, represents a small portion of
the species' currently occupied geographic range. In addition, although
the Saint John River is presumed to contain a relatively large
population of shortnose sturgeon, that populaiton is not considered the
largest, and it represents one of at least 10 spawning populations
(SSRT 2010). Furthermore, relatively recent field data indicate
shortnose sturgeon make coastal migrations to a greater extent than
previously thought (e.g., Dionne et al. 2013) and are capable of making
marine migrations of over 300 km (e.g., between Penobscot and Merrimack
rivers; M. Kieffer, USGS, pers. comm. 2010). Such data suggest the
potential for recolonization of the Saint John River by shortnose
sturgeon migrating from populations to the south. Further indirect
evidence in support of this possibility comes from the existing genetic
data, which indicate some level of gene flow among rivers in the
Northeast, including the Saint John River (Wirgin et al. 2005; Wirgin
et al. 2009; King et al. 2014). Thus, in light of the potential for
recolonization and the fact that the Saint John River population of
shortnose sturgeon does not constitute a substantial proportion of the
species' range, we conclude that the loss of the Saint John River would
not constitute a significant gap in the range of the species.

Only Natural Occurrence of the Taxon

Under the DPS Policy, a discrete population segment that represents
the ``only surviving natural occurrence of a taxon that may be more
abundant elsewhere as an introduced population outside its historical
range'' may be significant to the taxon as whole (61 FR 4722, February
7, 1996). This consideration is not relevant in this particular case,
because shortnose sturgeon are present in many river systems throughout
their historical range (SSRT 2010).

Genetic Characteristics

As stated in the DPS Policy, in assessing the ``significance'' of a
``discrete'' population, we consider whether the discrete population
segment differs markedly from other populations of the species in its
genetic characteristics (61 FR 4722, February 7, 1996). Therefore, we
examined the available data to determine whether the Saint John River
shortnose sturgeon differ markedly in their genetic characteristics
when compared to other populations. In conducting this evaluation under
the second criterion of the DPS policy, we looked beyond whether the
genetic data allow for discrimination of the Saint John population
segment from other populations (a topic of evaluation in connection
with the first criterion of ``discreteness''), and instead focused on
whether the data indicate marked genetic differences that appear to be
significant to the taxon as a whole. In this sense, we give independent
meaning to the ``genetic discontinuity'' of the discreteness criterion
of the DPS Policy and the ``markedly differing genetic
characteristics'' of the significance criterion.
Genetic analyses indicate fairly moderate to high levels of genetic
diversity of shortnose sturgeon in most river systems across the
geographic range (Grunwald et al. 2002, Quattro et al. 2002; Wirgin et
al. 2009). Based on the 11 nDNA loci examined in samples from 17
locations, King et al. (2014) reported that the number of observed
alleles (i.e., versions of a gene at a particular locus; here with
overall frequencies >1%) ranged from a low of 55 in the Cape Fear River
(n= 3 fish) to a high of 152 in the Hudson River (n= 45 fish); 118
alleles were observed in the Saint John River sample (n=25 fish).
Estimated heterozygosity was not reported by river sample, but King et
al. (2014) noted that it was lowest for the southern rivers relative to
the mid-Atlantic and northern river samples. Wirgin et al. (2009)
reported that haplotypic diversity ranged from 0.500 (Santee River,
n=4) to 0.862 (Altamaha River, n= 69) across 15 sample populations,
with the Saint John River population having a haplotype diversity index
of 0.696 (n=42). The number of individual haplotypes observed in any

[[Page 65193]]

one river sample ranged from two (Santee River, n=4) to 13 (Winyah Bay,
n=46), with eight haplotypes observed in the Saint John River sample
(n=42, Wirgin et al. 2009). The level of genetic diversity based on the
mtDNA was not correlated with population size, and there was also no
evidence of population bottlenecks, which may be due to historical
recency of most population declines (over past ~100 years, Grunwald et
al. 2002; Wirgin et al. 2009). Overall, the level of genetic diversity
observed for the Saint John River population segment is not unusual
relative to that observed in the taxon as a whole. However, Grunwald et
al. (2002) noted that the lack of reduced haplotypic diversity within
the northern sample rivers contrasts with findings for other anadromous
fishes from previously glaciated rivers. Grunwald et al. (2002)
hypothesized the high degree of haplotypic diversity and large number
of unique haplotypes in the previously glaciated northern region (i.e.,
Hudson River and northward) may be the result of a northern population
having survived in one or more northern refugia.
As discussed previously, at a regional scale, most of the mtDNA
haplotypes observed are shared across multiple, adjacent rivers
sampled; however, very little sharing of haplotypes has been documented
between the northern and southern portions of the range (Quattro et al.
2002; Grunwald et al. 2002; Wirgin et al. 2009). In the analysis
conducted by Wirgin et al. (2009), the Saint John River sample had one
private haplotype (in 1 of 42 fish) and shared the remaining 7
haplotypes with multiple rivers. Of the seven shared haplotypes, two
were each shared with two other river systems, including the Hudson and
Connecticut rivers, and the remaining five haplotypes were shared
across three to six other rivers within the northeast and mid-Atlantic
portions of the range (Wirgin et al. 2009). In an earlier study by
Quattro et al. (2002) in which control region mtDNA was sequenced for
211 shortnose sturgeon collected from five southeastern U.S. rivers and
the Saint John River, one haplotype was observed in all river samples.
This shared haplotype occurred in 1 of 13 fish (7.7%) sampled from the
Saint John River and 1 of 5 fish (20%) sampled from Winyah Bay; the
remaining river samples contained this haplotype at higher frequencies
(36%-79%, Quattro et al. 2002).
While the shortnose sturgeon from the Saint John River have a
fairly high degree of genetic diversity and shared haplotypes with
other rivers, they can be statistically differentiated from other river
samples based on haplotype frequencies and nDNA distance metrics
(Wirgin et al. 2009; King et al. 2014). However, the same is also true
for the majority of rivers across the range of the species. For
example, using genetic distances (Phi PT), King et al.
(2014) detected significant differences in all pairwise comparisons
except for three rivers in the northeast (Penobscot, Androscoggin, and
Kennebec rivers) and three rivers in the southeast (Edisto, Savannah,
and Ogeechee rivers). Similarly, significant differences in haplotype
frequencies have been reported for most river populations sampled. In
Chi-squared analyses, Grunwald et al. (2002) reported significant
differences for all but 4 of 82 pairwise comparisons of mtDNA
nucleotide substitution haplotype frequencies across 10 sample sets
(two of which were from different sections of the Connecticut River),
and Wirgin et al. (2009) reported significant differences for all but 9
of 91 pairwise comparisons of mtDNA haplotype frequencies across 13
river populations.
The magnitude of these genetic differences between individual river
systems varies across the range of the species and indicates a
hierarchical pattern of differentiation. For example, the mtDNA data
reveal a deep divergence between rivers in the northern portion of the
range from rivers in the southern portion of the range. Of the 29
haplotypes observed by Grunwald et al. (2002), 11 (37.9%) were
restricted to northern systems, 13 (44.8%) were restricted to the more
southern systems, and only 5 (17.2%) slightly overlapped the two
regions. In the later and larger study by Wirgin et al. (2009), the
observed haplotypes again clustered into regional groupings: 10 of 38
observed haplotypes (26.3%) only occurred in systems north of the
Hudson River, 16 of 38 (42.1%) only occurred in systems south of the
Chesapeake Bay, and just 5 of 38 (13.2%) haplotypes overlapped in the
mid-Atlantic region. The limited sharing of haplotypes between the
north and south regions is consistent with strong female homing
fidelity and limited gene flow between these regions. The break in
shared haplotypes corresponds with the historical division of the
species due to Pleistocene glaciation, which Grunwald et al. (2002)
stated was probably the most significant event affecting population
structure and patterns of mtDNA diversity in shortnose sturgeon.
The recent nDNA analyses of King et al. (2014) also indicate an
unambiguous differentiation of sample populations into one of three
major geographic groupings--Northeast, Mid-Atlantic, or Southeast. When
all 17 sample populations were pooled by these three geographic
regions, correct assignment to each region was 99.1% for the Northeast
and 100% (i.e., zero mi-assigned fish) for the remaining two regions
(King et al. 2014). Of the 133 fish included for the Northeast group,
one was mis-assigned to the Mid-Atlantic. The estimates of effective
migrants per generation (based on Phi PT) are consistent
with the regional zones of genetic discontinuity among Northeast, Mid-
Atlantic, and Southeast river systems. The average migrants per
generation between regions ranged from less than one migrant (i.e.,
0.89) between Northeast and Southeast to nearly two migrants (i.e.,
1.89) between Northeast and Mid-Atlantic. In contrast, the range of
estimated migrants per generation within regions was 2.25-83.08 for the
Northeast, 1.87-13.64 for the Mid-Atlantic, and 2.38-49.75 for the
Southeast (King et al. 2014). The estimated migrants per generation
between the Saint John River in particular and all other rivers within
the Northeast ranged from 2.25-3.43 (King et al. 2014). Taken together,
these data indicate that the degree of genetic differentiation between
the Saint John River and the rivers within the Gulf of Maine is
relatively small or ``shallow'', especially relative to the deeper
divergence observed among the regional groupings of river populations.
A possible explanation for the relatively low level of differentiation
within the Northeast is that the those populations are relatively young
in a geologic sense due to recent glaciations compared to populations
in the more southern part of the range (SSRT 2010).
In conclusion, given the patterns of genetic diversity, shared
haplotypes, and relative magnitudes of genetic divergence at the river
drainage versus regional scale, we find there is insufficient evidence
that the Saint John River population of shortnose sturgeon differs
markedly in its genetic characteristics relative to the taxon as a
whole so as to meet the test for ``significance'' on this basis. While
the Saint John River population segment can be genetically
distinguished from other river populations, available genetic evidence
places it into a larger evolutionarily meaningful unit, along with
several other river populations sampled. The degree of differentiation
among the three larger regional groups is more marked than the
differences observed among populations from the Saint John and other
nearest rivers, suggesting that the Saint John River

[[Page 65194]]

population's differentiation is not ``significant'' in the context of
the whole species. Gene flow estimates are also consistent with the
observed deeper zones of divergence detected at the regional scale.
Thus, we conclude that these data do not support delineation of the
Saint John River population segment as ``significant.'' In so
interpreting the available genetic data, we are mindful of the
Congressional guidance to use the DPS designation sparingly.

DPS Conclusion and Petition Finding

We conclude that the Saint John River population of shortnose
sturgeon is ``discrete'' based on evidence that it is a relatively
closed and somewhat geographically isolated population segment. It thus
satisfies the first prong of the DPS policy. However, we also find that
the Saint John River population segment is not ``significant'' to the
taxon as a whole. It thus fails to satisfy the second prong of the DPS
Policy. As such, based on the best available data, we conclude that the
Saint John River population of shortnose sturgeon does not constitute a
DPS and, thus, does not qualify as a ``species'' under the ESA.
Therefore, we deny the petition to consider this DPS for delisting. Our
denial of the petition on this ground does not imply any finding as to
how we should proceed if the situation were otherwise, i.e., where a
population is found instead to meet the criteria to be a DPS. Even if
the population had met both criteria of the DPS Policy, and even if the
population were also found to have a status that differed from the
listed entity, it would not necessarily be appropriate to propose
modifications to the current listing, in light of the unsettled legal
issues surrounding such revisions. Nor do we resolve here what steps
would need to be followed to propose revisions to the species' listing
if the facts had been otherwise; such an inquiry would be hypothetical
in this case. It is clear that because the petition at issue here
sought identification of a DPS, and because the population at issue is
not a DPS, this particular petition must be denied. As this is a final
action, we do not solicit comments on it.

References Cited

A complete list of references is available upon request to the
Office of Protected Resources (see ADDRESSES).

Authority

The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).

Dated: October 20, 2015.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine
Fisheries Service.
[FR Doc. 2015-27148 Filed 10-23-15; 8:45 am]
BILLING CODE 3510-22-P

Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules 65183

persistence and that should be further Summary of ESA Section 4(a)(1) provisions regarding the designation of
evaluated in a status review. Factors critical habitat.
The petitioners claim that hypoxia We conclude that the petition Information Solicited
(oxygen deficiency) has increased in presents substantial scientific or To ensure that the status review is
frequency, duration, and severity in commercial information indicating that based on the best available scientific
coastal waters and that this decreases a combination of three of the section and commercial data, we are soliciting
the abundance and diversity of benthic 4(a)(1) factors (overutilization for information on the thorny skate.
macrofauna (citing CSIS 2011). They commercial, recreational, scientific, or Specifically, we solicit information in
also claim that the combination of educational purposes; inadequate the following areas: (1) Historical and
hypoxia and increased water existing regulatory mechanisms; and current distribution and abundance of
temperature would reduce the quality other natural or manmade factors) may this species in the Northwest Atlantic;
and size of suitable habitat for aerobic be causing or contributing to an (2) historical and current population
organisms whose suitable habitat is increased risk of extinction for thorny status and trends; (3) any current or
restricted by water temperature and skate which needs to be further planned activities that may adversely
claim that thorny skate is such a evaluated in a review of the status of the impact the species, especially as related
species. While acknowledging that any species. to the five factors specified in section
prediction of the effects of hypoxic 4(a)(1) of the ESA and listed above; (4)
zones on thorny skates is speculative, Petition Finding
ongoing efforts to protect and restore the
the petitioners state that any adverse species and its habitat; and (5) genetic
impact on the species or on the After reviewing the information
contained in the petition, as well as data or other information related to
abundance/distribution of its predators possible population structure of thorny
or prey will severely hinder the species’ information readily available in our
files, and based on the above analysis, skate. We request that all information be
ability to recover. However, neither the accompanied by: (1) Supporting
petitioners nor the information in our we conclude the petition presents
substantial scientific information documentation such as maps,
files indicate that thorny skate are bibliographic references, or reprints of
impacted by hypoxia or that hypoxia indicating the petitioned action of
listing a Northwest Atlantic or United pertinent publications; and (2) the
may be contributing significantly to submitter’s name, address, and any
population declines in thorny skates to States DPS of thorny skate as threatened
or endangered may be warranted. association, institution, or business that
the point where the species may be at the person represents.
a risk of extinction. As such, we Therefore, in accordance with section
conclude that the information presented 4(b)(3)(B) of the ESA and NMFS’ References Cited
in the petition on the threat of hypoxia implementing regulations (50 CFR
424.14(b)(2)), we will commence a A complete list of references is
does not provide substantial available upon request (see ADDRESSES).
information indicating that hypoxia may review of the status of the species.
During our status review, we will first Authority
be impacting thorny skate to a degree
determine whether one of the
that the petitioned action may be The authority for this action is the
populations identified by the petitioners
warranted. Endangered Species Act of 1973, as
meets the DPS policy criteria, and if so,
The petitioners state that the life amended (16 U.S.C. 1531 et seq.).
whether it is threatened or endangered
history characteristics of thorny skate throughout all or a significant portion of Dated: October 16, 2015.
place the species at risk of adverse its range. We now initiate this review, Samuel D. Rauch, III.
effects resulting from natural stochastic and thus, the Northwest Atlantic Deputy Assistant Administrator for
events. However, neither the petitioners population of the thorny skate is Regulatory Programs, National Marine
nor the information in our files indicate considered to be a candidate species Fisheries Service.
that natural stochastic events are (see 69 FR 19975; April 15, 2004). To [FR Doc. 2015–27147 Filed 10–23–15; 8:45 am]
causing detrimental effects to the the maximum extent practicable, within BILLING CODE 3510–22–P
species or may be contributing 12 months of the receipt of the petition
significantly to population declines in (May 28, 2016), we will make a finding
thorny skates to the point where the as to whether listing either of the DEPARTMENT OF COMMERCE
species may be at a risk of extinction. populations identified by the petitioner
As such, we conclude that the as DPSs as endangered or threatened is National Oceanic and Atmospheric
information presented in the petition on warranted as required by section Administration
the threat of natural stochastic events 4(b)(3)(B) of the ESA. If listing a DPS is
does not provide substantial found to be warranted, we will publish 50 CFR Part 224
information indicating that such events a proposed rule and solicit public [Docket No. 150209121–5941–02]
may be impacting or may, in the comments before developing and
foreseeable future, impact thorny skate publishing a final rule. The petitioners RIN 0648–XD760
to a degree that the petitioned action request that we designate critical habitat Endangered and Threatened Wildlife;
may be warranted. However, given all of for thorny skates. ESA Section 4(a)(3)(A)
asabaliauskas on DSK5VPTVN1PROD with PROPOSALS

12-Month Finding on a Petition To
the information presented above on and its implementing regulations state Identify and Delist a Saint John River
other natural and manmade factors, that, to the maximum extent prudent Distinct Population Segment of
particularly the warming of oceans, the and determinable, the Secretary shall, Shortnose Sturgeon Under the
information in the petition and in our concurrently with listing a species as Endangered Species Act
files does lead a reasonable person to endangered or threatened, designate any
conclude that the petitioned action may critical habitat for that species. If a AGENCY: National Marine Fisheries
be warranted, and it is necessary to thorny skate population were to be Service (NMFS), National Oceanic and
consider the impacts from other natural listed as a DPS, we would follow the Atmospheric Administration (NOAA),
and manmade factors in a status review. relevant statutory and regulatory Department of Commerce.

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65184 Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules

ACTION: Notice of 12-month petition Preservation Act (ESPA, 32 FR 4001). biological evidence indicates that such
finding. Shortnose sturgeon remained on the action is warranted’’ (S. Rep. 96–151
endangered species list when the U.S. (1979)). The law is not settled as to the
SUMMARY: We, NMFS, announce a 12- Congress replaced the ESPA by enacting extent of the Services’ discretion to
month finding on a petition to identify the Endangered Species Conservation modify a species-level listing to
and ‘‘delist’’ shortnose sturgeon Act of 1969, which was in turn replaced recognize a DPS having a status that
(Acipenser brevirostrum) within the by the Endangered Species Act of 1973 differs from the original listing. In a
Saint John River in New Brunswick, (ESA, 16 U.S.C. 1531 et seq.). We recent decision, the United States
Canada under the Endangered Species subsequently assumed jurisdiction for District Court for the District of
Act (ESA). The shortnose sturgeon is shortnose sturgeon under a 1974 Columbia held that the ESA does not
currently listed as an endangered government reorganization plan (39 FR permit identification of a DPS solely for
species, at the species level, under the 41370, November 27, 1974). In Canada, purposes of delisting. Humane Soc’y v.
ESA. Based on our review of the best the shortnose sturgeon falls under the Jewell, 76 F. Supp. 3d 69 (D.D.C. Dec.
scientific and commercial data jurisdiction of the Department of 19, 2014), appeal docketed, No. 15–
available, we have determined that the Fisheries and Oceans (DFO) and was 5041 (D.C. Cir. Feb. 19, 2015) (Western
population of shortnose sturgeon from first assessed by the Committee on the Great Lakes gray wolves) (consolidated
the Saint John River does not qualify as Status of Endangered Wildlife in Canada with Nos. 15–5043, 15–5060, and 15–
a distinct population segment. (COSEWIC) as ‘‘Special Concern’’ in 5061).
Therefore, we did not consider the 1980. This status was reconfirmed in A species, subspecies, or DPS is
petition further, and we do not propose 2005, and the species was listed as ‘‘endangered’’ if it is in danger of
to delist this population. Special Concern under the Canadian extinction throughout all or a significant
DATES: This finding was made on federal Species at Risk Act (SARA) in portion of its range, and ‘‘threatened’’ if
October 26, 2015. 2009. The Special Concern status was it is likely to become endangered within
ADDRESSES: Information used to make reconfirmed again in 2015 (COSEWIC, the foreseeable future throughout all or
this finding is available for public In Press). Shortnose sturgeon is also a significant portion of its range (ESA
inspection by appointment during listed under Appendix I of the sections 3(6) and 3(20), respectively, 16
normal business hours at NMFS, Office Convention on International Trade in U.S.C. 1532(6) and (20)). We interpret
of Protected Resources, 1315 East-West Endangered Species of Wild Fauna an ‘‘endangered species’’ to be one that
Highway, Silver Spring, MD 20910. The (CITES). is presently in danger of extinction. A
petition and the list of the references Statutory, Regulatory and Policy ‘‘threatened species,’’ on the other hand,
used in making this finding are also Provisions is not presently in danger of extinction,
available on the NMFS Web site at: but is likely to become so in the
We are responsible for determining
www.nmfs.noaa.gov/pr/species/fish/ foreseeable future. In other words, the
whether species are threatened or
shortnose-sturgeon.html. primary statutory difference between a
endangered under the ESA (16 U.S.C.
FOR FURTHER INFORMATION CONTACT: Lisa 1531 et seq.). To make this threatened and endangered species is
Manning, Office of Protected Resources, determination, we first consider the timing of when a species may be in
301–427–8466; Stephania Bolden, whether a group of organisms danger of extinction, either presently
Southeast Regional Office, 727–824– constitutes a ‘‘species’’ under section 3 (endangered) or in the foreseeable future
5312; Julie Crocker, Greater Atlantic of the ESA, and then we consider (threatened). In addition, we interpret
Regional Office, 978–282–8480. whether the status of the species ‘‘foreseeable future’’ as the horizon over
SUPPLEMENTARY INFORMATION: qualifies it for listing as either which predictions about the
threatened or endangered. Section 3 of conservation status of the species can be
Background reasonably relied upon.
the ESA defines a ‘‘species’’ to include
On September 24, 2014, we received ‘‘any subspecies of fish or wildlife or Pursuant to the ESA and our
a petition from Dr. Michael J. Dadswell, plants, and any distinct population implementing regulations, the
Dr. Matthew K. Litvak, and Mr. Jonathan segment of any species of vertebrate fish determination of whether a species is
Barry regarding the population of or wildlife which interbreeds when threatened or endangered shall be based
shortnose sturgeon (Acipenser mature’’ (16 U.S.C. 1532(16)). A joint on any one or a combination of the
brevirostrum) native to the Saint John policy issued by NMFS and the U.S. following five section 4(a)(1) factors:
River in New Brunswick, Canada. The Fish and Wildlife Service (USFWS; The present or threatened destruction,
petition requests that we identify the collectively referred to as ‘‘the modification, or curtailment of habitat
Saint John River population of Services’’) clarifies the interpretation of or range; overutilization for commercial,
shortnose sturgeon as a distinct the phrase ‘‘distinct population recreational, scientific, or educational
population segment (DPS) and segment’’ (DPS) for the purposes of purposes; disease or predation;
contemporaneously ‘‘delist’’ this DPS by listing, delisting, and reclassifying a inadequacy of existing regulatory
removing it from the species-wide species under the ESA (‘‘DPS Policy,’’ mechanisms; and any other natural or
listing under the Endangered Species 61 FR 4722, February 7, 1996). The DPS manmade factors affecting the species’
Act. On April 6, 2015, we published a Policy identifies two criteria for existence. 16 U.S.C. 1533(a)(1); 50 CFR
positive finding indicating that the determining whether a population is a 424.11(c). Listing determinations must
asabaliauskas on DSK5VPTVN1PROD with PROPOSALS

petitioned action may be warranted and DPS: (1) The population must be be based solely on the best scientific
that we were initiating a status review ‘‘discrete’’ in relation to the remainder and commercial data available, after
to consider the petition further (80 FR of the taxon (species or subspecies) to conducting a review of the species’
18347). which it belongs; and (2) the population status and after taking into account any
The shortnose sturgeon was originally must be ‘‘significant’’ to the remainder efforts being made by any state or
listed as an endangered species of the taxon to which it belongs. foreign nation (or any political
throughout its range by the U.S. Fish Congress has instructed the Secretary subdivision of such state or foreign
and Wildlife Service (USFWS) on March to exercise the authority to recognize nation) to protect the species. 16 U.S.C.
11, 1967, under the Endangered Species DPS’s ‘‘sparingly and only when the 1532(b)(1)(A).

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$Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules 65185 Under section 4(a)(1) of the ESA and determining whether particular DPS(s) on the ventral surface. Adults have no the implementing regulations at 50 CFR exist(s) (based on meeting the criteria of teeth but possess bony plates in the 424.11(d), a species shall be removed the DPS Policy) and, if that finding is esophagus that are used to crush hard from the list if the Secretary of affirmative, complex evaluation as to prey items (Vladykov and Greeley 1963; Commerce determines, based on the the most appropriate approach for Gilbert 1989). The skeleton is almost best scientific and commercial data managing the species in light of the entirely cartilaginous with the exception available after conducting a review of purposes and authorities under the ESA. of some bones in the skull, jaw and the species’ status, that the species is no pectoral girdle. longer threatened or endangered Species Description Shortnose sturgeon occur along the because of one or a combination of the Below, we summarize basic life East Coast of North America in rivers, section 4(a)(1) factors. The regulations history information for shortnose estuaries, and marine waters. provide that a species listed under the sturgeon. A more thorough discussion of Historically, they were present in most ESA may be delisted only if such data all life stages, reproductive biology, major rivers systems along the Atlantic substantiate that it is neither habitat use, abundance estimates and coast (Kynard 1997). Their current endangered nor threatened for one or threats are provided in the Shortnose riverine distribution extends from the more of the following reasons: Sturgeon Biological Assessment Saint John River, New Brunswick, (1) Extinction. Unless all individuals of the completed by the Shortnose Sturgeon Canada, to possibly as far south as the listed species had been previously identified Status Review Team in 2010 (SSRT St. Johns River, Florida (Figure 1; and located, and were later found to be 2010; http://www.fisheries.noaa.gov/pr/ Kynard 1997; Gorham and McAllister extirpated from their previous range, a species/fish/shortnose-sturgeon.html). sufficient period of time must be allowed 1974). Recently available information before delisting to indicate clearly that the There are 25 species and four indicates that their marine range species is extinct. recognized genera of sturgeons (family extends farther northward than (2) Recovery. The principal goal of the Acipenseridae), which comprise an previously thought and includes the USFWS and NMFS is to return listed species ancient and distinctive assemblage with Minas Basin, Nova Scotia (Dadswell et to a point at which protection under the ESA fossils dating to at least the Upper al. 2013). The distribution of shortnose is no longer required. A species may be Cretaceous period, more than 66 million sturgeon across their range, however, is delisted on the basis of recovery only if the best scientific and commercial data available years ago (Findeis 1997). The shortnose disjunct, with no known reproducing indicate that it is no longer endangered or sturgeon, Acipenser brevirostrum, is the populations occurring within the threatened. smallest of the three extant sturgeon roughly 400 km of coast between the (3) Original data for classification in error. species in eastern North America. Many Chesapeake Bay and the southern Subsequent investigations may show that the primitive physical characteristics that boundary of North Carolina. Shortnose best scientific or commercial data available reflect the shortnose sturgeon’s ancient sturgeon live in close proximity with when the species was listed, or the lineage have been retained, including a Atlantic sturgeon (Acipenser oxyrinchus interpretation of such data, were in error. protective armor of bony plates called oxyrinchus) throughout much of their 50 CFR 424.11(d). ‘‘scutes’’; a subterminal, protractile range. However, Atlantic sturgeon To complete the required finding in tube-like mouth; and chemosensory spend more of their life cycle in the response to the current delisting barbels. The general body shape is open ocean compared to shortnose petition, we first evaluated whether the cylindrical, tapering at the head and sturgeon. Within rivers, shortnose petitioned entity meets the criteria of caudal peduncle, and the upper lobe of sturgeon and Atlantic sturgeon may the DPS Policy. As we noted in our the tail is longer than the lower lobe. share foraging habitat and resources, but initial petition finding, a determination Shortnose sturgeon vary in color but are shortnose sturgeon generally spawn whether to revise a species-level listing generally dark brown to olive or black farther upriver and earlier than Atlantic to recognize one or more DPSs in place on the dorsal surface, lighter along the sturgeon (Kynard 1997, Bain 1997). of a species-level listing involves, first, row of lateral scutes, and nearly white BILLING CODE 3510–22–P asabaliauskas on DSK5VPTVN1PROD with PROPOSALS VerDate Sep<11>2014 18:00 Oct 23, 2015 Jkt 238001 PO 00000 Frm 00017 Fmt 4702 Sfmt 4702 E:\FR\FM\26OCP1.SGM 26OCP1$

65188 Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules

4,701–4,971) adult shortnose sturgeon submitted in response to our 90-day riverine movements of adult shortnose
were overwintering in that area. finding (80 FR 18347, April 6, 2015). sturgeon occur fairly frequently among
Usvyatsov et al. (2012) repeated this For purposes of this analysis, we rivers in Maine. Seventy percent of
sampling in 2009 and 2011 and, using defined the Saint John River population tagged adults (25 of 41 fish) moved
three different modeling techniques, segment of shortnose sturgeon to consist between the Penobscot and Kennebec
estimated a total of 3,852–5,222 of shortnose sturgeon spawned in the rivers (about 150 km away), and up to
shortnose sturgeon in the study area, Saint John River downstream of the 52% of the coastal migrants (13 of 25
which suggests fairly stable abundance Mactaquac Dam. Prior to construction of fish) also used other, smaller river
and habitat use at this site. Mactaquac Dam in 1968/1969, sturgeon systems (i.e., Damariscotta, Medomak,
Threats that contributed to the occurred upstream of the dam; however, St. George) between the Penobscot and
species’ decline and led to the listing of it is unclear whether these were Kennebec rivers (Zydlewski et al. 2011).
shortnose sturgeon under the ESA shortnose and/or Atlantic sturgeon and Shortnose sturgeon are also known to
included pollution, overfishing, and whether any sturgeon are still present move between rivers in Maine and (e.g.,
bycatch in the shad fishery (USDOI upstream of the dam (COSEWIC, In Kennebec, Saco) and the Merrimack
1973). Shortnose sturgeon were also Press). Lacking this information, we River estuary in Massachusetts,
thought to be extirpated, or nearly so, cannot consider fish that may be present traveling distances of up to about 250
from most of the rivers in their upstream of the dam in our distinct km (as measured by a conservative,
historical range (USDOI 1973). In the population segment analysis. direct path distance; Little et al. 2013;
late nineteenth and early twentieth Throughout our discussion below we Wippelhauser et al. 2015). At the other
centuries, shortnose sturgeon were also use the term ‘‘population’’ to refer end of the range, in the Southeast
commonly harvested incidental to collectively to all shortnose sturgeon United States, inter-riverine movements
Atlantic sturgeon, the larger and more that are presumed to be natal to a appear fairly common and include
commercially valuable of these two particular river rather than using this movements between the Savannah River
sympatric sturgeon species (NMFS term to refer strictly to a completely and Winyah Bay and between the
1998). Although there is currently no closed reproductive unit. Altamaha and Ogeechee rivers (Peterson
legal directed fishing for shortnose and Farrae 2011; Post et al. 2014).
Discreteness Criterion
sturgeon in the United States, poaching Many inter-riverine movements have
is suspected, and bycatch still occurs in The Services’ joint DPS Policy states been observed elsewhere within the
some areas. In particular, shortnose that a population segment of a species’ range, but patterns are not yet
sturgeon are caught incidentally by bass vertebrate species may be considered well resolved. For example, some
anglers and in the alewife/gaspereau, discrete if it satisfies either one of the shortnose sturgeon captured and/or
American shad, American eel, and following conditions: tagged in the Connecticut River have
Atlantic sturgeon fisheries in the Saint (1) It is markedly separated from other been recaptured, detected, or were
John River; and shad fisheries in the populations of the same taxon as a previously tagged in the Housatonic
Altamaha River, Santee River, Savannah consequence of physical, physiological, River (T. Savoy, CT DEP, pers. comm.
River, and elsewhere (COSEWIC, In ecological, or behavioral factors. 2015), the Hudson River (Savoy 2004),
Press; SSRT 2010; Bahn et al. 2009; Quantitative measures of genetic or and the Merrimack River (M. Kieffer,
COSEWIC 2005). The construction of morphological discontinuity may USGS, pers. comm. 2015). At this time,
dams has also resulted in substantial provide evidence of this separation. the available tagging and tracking
loss of historical shortnose sturgeon (2) It is delimited by international information is too limited to determine
habitat in some areas along the Atlantic governmental boundaries within which if Hudson River and Connecticut River
seaboard. The construction and differences in control of exploitation, shortnose sturgeon are making regular
operation of dams can impede upstream management of habitat, conservation movements outside of their natal rivers
movement to sturgeon spawning habitat status, or regulatory mechanisms exist and whether movement as far as the
(e.g., Connecticut River, Santee River). that are significant in light of section Merrimack River is a normal behavior.
Remediation measures, such as dam 4(a)(1)(D) of the ESA (61 FR 4722, Movement data from the Chesapeake
removal or modification to allow for fish February 7, 1996). Bay is also relatively limited, but
passage have improved access in some There are no physical barriers
existing data indicate that shortnose
rivers, and additional similar restoration preventing the movement of Saint John
sturgeon do move from the Chesapeake
efforts are being considered in other River shortnose sturgeon outside of the
Bay through the Chesapeake and
areas (e.g., possible removal of the Saint John River estuary or along the
Delaware Canal into the Delaware River
Mactaquac dam in the Saint John River). coast. The Mactaquac Dam, located
(Welsh et al. 2002).
Other possible and ongoing threats about 140 km upstream and at the head The distances of the reported marine
include operation of power generating of tide (Canadian Rivers Institute 2011), migrations vary widely from very short
stations, water diversion projects, is the first upstream physical barrier on distances—such as between the Santee
dredging, and other in-water activities the Saint John River. This and other River and Winyah Bay, which are only
that impact habitat. dams on the Saint John River block about 15 km apart—to fairly long—as in
shortnose sturgeon from accessing the case of movements between the
Distinct Population Segment Analysis upstream habitats, but there are no dams Merrimack and the Penobscot rivers,
The following sections provide our or other physical barriers separating
asabaliauskas on DSK5VPTVN1PROD with PROPOSALS

which are about 339 km apart at their
analysis of whether the petitioned Saint John River sturgeon from other mouths.1 In general, the available data
entity—the Saint John River population shortnose sturgeon populations.
of shortnose sturgeon—qualifies as a As mentioned previously, shortnose 1 Distances between rivers mouths reported here
DPS of shortnose sturgeon (whether it is sturgeon have been documented to leave were measured in GIS using the NOAA Medium
both ‘‘discrete’’ and ‘‘significant’’). To their natal river/estuary and move to Resolution Vector Shoreline, 20m bathymetry
complete this analysis we relied on the other rivers to varying extents across contour, and a fixed scale of 1:250,000. Estimated
distances reported are the average of three,
best scientific and commercial data their range. For example, telemetry data independently drawn and measured paths for each
available and considered all relevant generated by Zydlewski et al. (2011) river pair. The assumed travel path between river
literature and public comments during 2008–2010 indicate that inter- mouths was the shortest possible distance that

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Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules 65189

suggest that movements between systems, there are no available data on data have consistently indicated an
geographically proximate rivers are coastal migrations of Saint John River overall isolation-by-distance pattern of
more common, while movements shortnose sturgeon. To date, there are genetic population structure across the
between more distant rivers do not, or also no reported observations or species’ range, meaning that
only rarely, occur. A detailed discussion detections of shortnose sturgeon from populations of shortnose sturgeon
of the physical movements of shortnose the Gulf of Maine rivers moving into the inhabiting rivers and embayments that
sturgeon is provided in SSRT 2010. Saint John River. Thus, while it is are geographically more distant tend to
The extent of coastal movements of possible that the Saint John River be less related than those that are
shortnose sturgeon from the Saint John shortnose sturgeon come in contact with geographically closer (e.g., Walsh et al.
River is currently unknown (COSEWIC, shortnose sturgeon from elsewhere, it is 2001, Grunwald et al. 2002, Waldman et
In Press); however, some limited data also likely that some degree of al. 2002, and Wirgin et al. 2005; Wirgin
are available and provide some insight geographical isolation by distance is et al. 2009). The haplotypes observed
into whether these fish may be occurring. are typically shared across two to four
geographically isolated from other Although acoustic telemetry studies or more adjacent sampled rivers but
populations. Any movement between have revealed that shortnose sturgeon with little sharing of haplotypes
Saint John River sturgeon and the leave their natal river systems to a much between northern and southern
nearest population in the Penobscot greater extent than previously thought, populations (Waldman et al. 2002;
River would require a marine migration such movements do not necessarily Wirgin et al. 2009). Results for the Saint
of about 362 km, a similar travel constitute permanent emigration or John River are compatible with these
distance as between the Merrimack and indicate interbreeding of populations. general patterns. For example, in the
the Penobscot rivers (340 km) and Tagging and telemetry studies within largest study to date, Wirgin et al. (2009)
between the Connecticut and Merrimack several river systems have provided observed eight haplotypes within the
rivers (348 km).2 Dadswell (1979) evidence that shortnose sturgeon in Saint John River sample (n=42); and of
reported that of 121 marked Saint John those particular systems tend to spawn the eight observed haplotypes, one was
River shortnose sturgeon recaptured by in their natal river (e.g., Dovel 1981; exclusive (or ‘‘private’’) to the Saint
commercial fisherman, 13 fish (11 Buckley and Kynard 1985; Kieffer and John River (and observed in 1 of 42
percent) were recaptured in the Bay of Kynard 1993; O‘Herron et al. 1993; fish), and the remaining haplotypes
Fundy, indicating that a portion of the Kieffer and Kynard 1996). Tag return were shared with two to six other rivers.
population migrated into the marine data for shortnose sturgeon in the Saint None of the shared haplotypes were
environment. In addition, a confirmed John River over the course of a 4-year observed in samples south of the
shortnose sturgeon was caught in a study completed by Dadswell (1979) Chesapeake Bay. A previously
fishing weir in the Minas Basin, off the suggests there is little emigration from unreported haplotype was recently
coast of Nova Scotia about 165 km north this system as well, and that spawning observed in 2 of 15 shortnose caught
of the mouth of the Saint John River takes place in the freshwater sections of from the Kennebecasis River, a tributary
(Dadswell et al. 2013). Fishermen in the the upper estuary. The high site fidelity of the Saint John (Kerr, 2015; P. Wilson,
Minas Basin also claim to catch about to natal rivers suggested by this and public comment, May 2015). This new
one to two shortnose sturgeon per year other studies indicates a there is a haplotype could indicate an even
in their weirs (Dadswell et al. 2013). possible behavioral mechanism for the greater degree of differentiation of the
While it is plausible that the shortnose marked separation of the Saint John Saint John River fish; however, no other
sturgeon captured in the Minas Bay River population of shortnose sturgeon
rivers were sampled or analyzed as part
originated from the Saint John River, from other populations of the species.
of this study.
data to confirm this are not available. In A substantial amount of genetic data
contrast, limited telemetry data suggest has become available since the ‘‘Final Despite the localized sharing of
that movements outside of the Saint Recovery Plan for Shortnose Sturgeon’’ haplotypes, frequencies of the observed
John River are not common. Of 64 was developed in 1998. Below, we haplotypes are significantly different in
shortnose sturgeon tagged in the Saint summarize the best available genetic most pairwise comparisons of the rivers
John River over the course of about 16 data and information, which informed sampled (i.e., comparisons of haplotype
years from 1999 to 2015, none have our evaluation of the ‘‘discreteness’’ of frequencies from samples from two
been detected moving past the farthest the Saint John River population rivers), including many adjacent rivers
downriver acoustic receiver located near segment. A more in-depth presentation (Wirgin et al. 2009). Such pairwise
the Saint John Harbor Bridge (M. Litvak, of genetic data, including discussions of comparisons for the Saint John River in
pers. comm. July 31, 2015). types of analyses and assumptions, is particular have indicated that this
Overall, while there is unambiguous available in the Biological Assessment population is genetically distinct from
evidence that shortnose sturgeon from (SSRT 2010). the geographically closest sampled
the Saint John River leave the estuary— Much of the published information on populations, including the Penobscot,
at least occasionally—and use the population structure for shortnose Kennebec, and Androscoggin rivers
marine environment, and that shortnose sturgeon has been based on the genetic (Grunwald et al. 2002; Waldman et al.
sturgeon are capable of making long analysis of the maternally inherited 2002; Wirgin et al. 2005; Wirgin et al.
distance movements between river mitochondrial DNA (mtDNA) due in 2009). For example, Wirgin et al. (2009)
part to the difficulties of analyzing data reported significant differences
asabaliauskas on DSK5VPTVN1PROD with PROPOSALS

followed the general outline of the coast and was from the polyploid nuclear genome (p<0.0005) in haplotype frequencies
constrained by the 20m bathymetry contour, except (Waldman et al. 2008). The analyses between Saint John River shortnose
where the shortest travel path across a deep, narrow
inlet or bay crossed the 20m bathymetry contour.
have focused on a moderately sturgeon (n=42) and Penobscot (n=44,
2 Distances reported here were measured polymorphic 440 base pair portion of Chi-square=37.22), Kennebec (n=54,
following the same methods described in the the mtDNA control region—a relatively Chi-square=54.85), and Androscoggin
previous footnote. The distance reported between rapidly evolving region of mtDNA and (n=48, Chi-square=37.91) river samples.
the Connecticut and Merrimack River assumes a
travel path via the Cape Cod Canal. A travel path
thus a good indicator of population- The level of genetic differentiation
around Cape Cod would instead result in a marine level differentiation. Haplotype between the Saint John River population
migration of about 560 km. frequencies and sequence divergence and the Penobscot, Kennebec, and

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65190 Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules

Androscoggin rivers also appears panmixia (i.e., random mating of studies provide indirect evidence that
substantial, with Phi ST values ranging individuals) among the Penobscot, the Saint John River population is
from 0.213 to 0.291 (where Phi ST ranges Kennebec, and Androscoggin rivers; relatively reproductively isolated.
from 0 to 1, with 1 indicating complete whereas, the Saint John and Merrimack As highlighted in the DPS Policy,
isolation; Wirgin et al. 2009). rivers appeared more differentiated from quantitative measures of morphological
Estimates of female-mediated gene each other as well as from the other Gulf discontinuity or differentiation can
flow between the Saint John River and of Maine rivers (King et al. 2014). serve as evidence of marked separation
the Gulf of Maine rivers are fairly low. Pairwise comparisons at the population of populations. We examined whether
Wirgin et al. (2009) estimated female- level showed that, within the Northeast the morphological data for shortnose
mediated gene flow between the Saint region, estimates of genetic sturgeon across its range provide
John River and other Gulf of Maine differentiation were greatest between evidence of marked separation of the
rivers as 1.90–2.85 female migrants per the Saint John and Merrimack rivers Saint John River population. As noted
generation based on Phi ST values, and (Phi PT = 0.100, p <0.0004), the two most previously, maximum adult size (length
as 1.5–1.9 females per generation in a distant rivers within this region. and weight) varies across the range,
separate, coalescent-based analysis. This Pairwise comparisons of the Saint John with the largest maximum sizes
result suggests that (if model River to the remaining rivers within the occurring in the Saint John River at the
assumptions are true) no more than Northeast region revealed lower but still northernmost end of the range, and the
three female shortnose sturgeon from statistically significant levels of genetic smallest sizes occurring in rivers at the
the Saint John River are likely to spawn differentiation (Phi PT = 0.068–0.077; southern end of the range (Dadswell et
in the other Gulf of Maine rivers (or vice King et al. 2014). Relatively low levels al. 1984). The largest individual
versa) per generation. These results of differentiation were observed in reported in the literature (122 cm FL,
provide additional evidence that the pairwise comparisons for all other rivers 23.6 kg) was captured in the Saint John
degree of female-based reproductive within the Northeast region (Phi PT = River, although there is also a report of
exchange between the Saint John River 0.013–0.087), half of which were not a specimen measuring 124.6 cm FL (M.
population and other nearby shortnose statistically significant (King et al. Litvak, unpublished data, as cited in
river populations has been relatively 2014). In comparison, within the Mid- COSEWIC, In Press). Lengths of
limited over many generations. Atlantic group, pairwise comparisons shortnose sturgeon captured in surveys
More recently, King et al. (2014) among rivers showed moderate levels of of the Saint John River in 1974–1975
completed a series of analyses using genetic differentiation among most river ranged from 60 to 120 cm FL (n=1,621).
nuclear DNA (nDNA) samples from 17 populations (average Phi PT = 0.077, The majority of these fish, however,
extant shortnose sturgeon populations range = 0.018–0.118); whereas, were smaller than 100 cm FL (1,476
across the species range. In contrast to estimates of population level genetic fish), and only six fish were longer than
the maternally inherited mtDNA, nDNA differentiation were very low among 111 cm FL (Dadswell 1979). To the
reflects the genetic inheritance from samples populations in the Southeast south, in the Kennebec River, Maine
both the male and female parents. King group (average Phi PT = 0.047, range = shortnose sturgeon captured during
et al. (2014) surveyed the samples at 11 0.005 to 0.095; King et al. 2014), 1980 and 1981 had lengths ranging from
polysomic microsatellite DNA loci and suggesting a more genetically similar set 58.5 to 103.0 cm FL, and averaging 80.8
then evaluated the 181 observed alleles of populations. cm FL (n=24; Walsh et al. 2001).
as presence/absence data using a variety Theoretical estimates of gene flow Smaller size ranges are reported for
of analytical techniques. The population (derived from Phi PT values) between the rivers in the southernmost portion of the
structuring revealed by these analyses is Saint John River and the other Northeast range with some occasional captures of
consistent with the previous mtDNA rivers ranged from 2.25 to 3.43 migrants larger specimens. For example, adult
analyses in that they also indicate a per generation (King et al. 2014). Gene shortnose sturgeon captured in the
regional scale isolation-by-distance flow estimates for the Merrimack River Altamaha River, Georgia, in 2010–2013
pattern of genetic differentiation. were similarly low, ranging from 2.25 to ranged from 57.4–83.0 cm FL and
Analysis of genetic distances among 4.06 (King et al. 2014). In contrast, the averaged 70.1 cm long (FL, n=40;
individual fish (using principle effective number of migrants per Peterson 2014), but a shortnose sturgeon
coordinate analysis, PCO) revealed that generation estimated to occur between measuring 104.5 cm FL and weighing
the sampled fish grouped into one of the remaining rivers within the 8.94 kg was captured in the Altamaha
three major geographic units: (1) Northeast region was much higher and River in summer, 2004 (D. Peterson,
Northeast, which included samples ranged from 16.42 to 83.08 (King et al. UGA, unpubl. data). Overall, the
from the Saint John, Penobscot, 2014). attribute of size appears to display clinal
Kennebec, Androscoggin, and Overall, the analyses completed by variation, meaning there is a gradual
Merrimack rivers; (2) Mid-Atlantic, King et al. (2014) indicate that change with geographic location
which included samples from the differentiation among Northeast (Huxley 1938). The fact that the Saint
Connecticut, Hudson, and Delaware populations is less than that observed John River population segment, which
rivers, as well as the Chesapeake Bay among the Mid-Atlantic populations lies at the northernmost end of the
proper; and (3) Southeast, which and greater than that observed among range, exhibits the largest sizes does not
included samples from the Cape Fear Southeast populations. However, within in itself constitute a morphological
River, Winyah Bay, the Santee-Cooper, the Northeast region, both the Saint discontinuity. Given the apparent
asabaliauskas on DSK5VPTVN1PROD with PROPOSALS

Edisto, Savannah, Ogeechee, and John and Merrimack River sample gradual nature of the variation in size
Altamaha rivers, and Lake Marion (King populations are genetically distinct from with latitude, we find that there is no
et al. 2014). the other sample populations. Although marked separation of the Saint John
Subsequent analyses revealed that the estimates of gene flow suggest some River population segment on the basis
each of the three regions has a different connectivity between the Saint John and of a quantitative discontinuity in size.
pattern of sub-structuring. Within the other rivers within the Northeast, the In addition to body size, other
Northeast group, two separate analyses significantly different allele and attributes such as snout length, head
(PCO and STRUCTURE) indicated a haplotype frequencies shown length, and mouth width can provide
high degree of relatedness and possible consistently in the nDNA and mtDNA evidence of a morphological

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Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules 65193

one river sample ranged from two river samples based on haplotype groupings—Northeast, Mid-Atlantic, or
(Santee River, n=4) to 13 (Winyah Bay, frequencies and nDNA distance metrics Southeast. When all 17 sample
n=46), with eight haplotypes observed (Wirgin et al. 2009; King et al. 2014). populations were pooled by these three
in the Saint John River sample (n=42, However, the same is also true for the geographic regions, correct assignment
Wirgin et al. 2009). The level of genetic majority of rivers across the range of the to each region was 99.1% for the
diversity based on the mtDNA was not species. For example, using genetic Northeast and 100% (i.e., zero mi-
correlated with population size, and distances (Phi PT), King et al. (2014) assigned fish) for the remaining two
there was also no evidence of detected significant differences in all regions (King et al. 2014). Of the 133
population bottlenecks, which may be pairwise comparisons except for three fish included for the Northeast group,
due to historical recency of most rivers in the northeast (Penobscot, one was mis-assigned to the Mid-
population declines (over past ∼100 Androscoggin, and Kennebec rivers) and Atlantic. The estimates of effective
years, Grunwald et al. 2002; Wirgin et three rivers in the southeast (Edisto, migrants per generation (based on Phi
al. 2009). Overall, the level of genetic Savannah, and Ogeechee rivers). PT) are consistent with the regional
diversity observed for the Saint John Similarly, significant differences in zones of genetic discontinuity among
River population segment is not unusual haplotype frequencies have been Northeast, Mid-Atlantic, and Southeast
relative to that observed in the taxon as reported for most river populations river systems. The average migrants per
a whole. However, Grunwald et al. sampled. In Chi-squared analyses, generation between regions ranged from
(2002) noted that the lack of reduced Grunwald et al. (2002) reported less than one migrant (i.e., 0.89)
haplotypic diversity within the northern significant differences for all but 4 of 82 between Northeast and Southeast to
sample rivers contrasts with findings for pairwise comparisons of mtDNA nearly two migrants (i.e., 1.89) between
other anadromous fishes from nucleotide substitution haplotype Northeast and Mid-Atlantic. In contrast,
previously glaciated rivers. Grunwald et frequencies across 10 sample sets (two the range of estimated migrants per
al. (2002) hypothesized the high degree of which were from different sections of generation within regions was 2.25–
of haplotypic diversity and large the Connecticut River), and Wirgin et al. 83.08 for the Northeast, 1.87–13.64 for
number of unique haplotypes in the (2009) reported significant differences the Mid-Atlantic, and 2.38–49.75 for the
previously glaciated northern region for all but 9 of 91 pairwise comparisons Southeast (King et al. 2014). The
(i.e., Hudson River and northward) may of mtDNA haplotype frequencies across estimated migrants per generation
be the result of a northern population 13 river populations. between the Saint John River in
having survived in one or more northern The magnitude of these genetic particular and all other rivers within the
refugia. differences between individual river Northeast ranged from 2.25–3.43 (King
As discussed previously, at a regional systems varies across the range of the et al. 2014). Taken together, these data
scale, most of the mtDNA haplotypes species and indicates a hierarchical indicate that the degree of genetic
observed are shared across multiple, pattern of differentiation. For example, differentiation between the Saint John
adjacent rivers sampled; however, very the mtDNA data reveal a deep River and the rivers within the Gulf of
little sharing of haplotypes has been divergence between rivers in the Maine is relatively small or ‘‘shallow’’,
documented between the northern and northern portion of the range from rivers especially relative to the deeper
southern portions of the range (Quattro in the southern portion of the range. Of divergence observed among the regional
et al. 2002; Grunwald et al. 2002; Wirgin the 29 haplotypes observed by groupings of river populations. A
et al. 2009). In the analysis conducted Grunwald et al. (2002), 11 (37.9%) were possible explanation for the relatively
by Wirgin et al. (2009), the Saint John restricted to northern systems, 13
low level of differentiation within the
River sample had one private haplotype (44.8%) were restricted to the more
Northeast is that the those populations
(in 1 of 42 fish) and shared the southern systems, and only 5 (17.2%)
are relatively young in a geologic sense
remaining 7 haplotypes with multiple slightly overlapped the two regions. In
due to recent glaciations compared to
rivers. Of the seven shared haplotypes, the later and larger study by Wirgin et
populations in the more southern part of
two were each shared with two other al. (2009), the observed haplotypes
the range (SSRT 2010).
river systems, including the Hudson and again clustered into regional groupings:
Connecticut rivers, and the remaining 10 of 38 observed haplotypes (26.3%) In conclusion, given the patterns of
five haplotypes were shared across three only occurred in systems north of the genetic diversity, shared haplotypes,
to six other rivers within the northeast Hudson River, 16 of 38 (42.1%) only and relative magnitudes of genetic
and mid-Atlantic portions of the range occurred in systems south of the divergence at the river drainage versus
(Wirgin et al. 2009). In an earlier study Chesapeake Bay, and just 5 of 38 regional scale, we find there is
by Quattro et al. (2002) in which control (13.2%) haplotypes overlapped in the insufficient evidence that the Saint John
region mtDNA was sequenced for 211 mid-Atlantic region. The limited sharing River population of shortnose sturgeon
shortnose sturgeon collected from five of haplotypes between the north and differs markedly in its genetic
southeastern U.S. rivers and the Saint south regions is consistent with strong characteristics relative to the taxon as a
John River, one haplotype was observed female homing fidelity and limited gene whole so as to meet the test for
in all river samples. This shared flow between these regions. The break ‘‘significance’’ on this basis. While the
haplotype occurred in 1 of 13 fish in shared haplotypes corresponds with Saint John River population segment
(7.7%) sampled from the Saint John the historical division of the species due can be genetically distinguished from
River and 1 of 5 fish (20%) sampled to Pleistocene glaciation, which other river populations, available
asabaliauskas on DSK5VPTVN1PROD with PROPOSALS

from Winyah Bay; the remaining river Grunwald et al. (2002) stated was genetic evidence places it into a larger
samples contained this haplotype at probably the most significant event evolutionarily meaningful unit, along
higher frequencies (36%–79%, Quattro affecting population structure and with several other river populations
et al. 2002). patterns of mtDNA diversity in sampled. The degree of differentiation
While the shortnose sturgeon from the shortnose sturgeon. among the three larger regional groups
Saint John River have a fairly high The recent nDNA analyses of King et is more marked than the differences
degree of genetic diversity and shared al. (2014) also indicate an unambiguous observed among populations from the
haplotypes with other rivers, they can differentiation of sample populations Saint John and other nearest rivers,
be statistically differentiated from other into one of three major geographic suggesting that the Saint John River

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$65194 Federal Register / Vol. 80, No. 206 / Monday, October 26, 2015 / Proposed Rules population’s differentiation is not Policy. As such, based on the best be hypothetical in this case. It is clear ‘‘significant’’ in the context of the whole available data, we conclude that the that because the petition at issue here species. Gene flow estimates are also Saint John River population of sought identification of a DPS, and consistent with the observed deeper shortnose sturgeon does not constitute a because the population at issue is not a zones of divergence detected at the DPS and, thus, does not qualify as a DPS, this particular petition must be regional scale. Thus, we conclude that ‘‘species’’ under the ESA. Therefore, we denied. As this is a final action, we do these data do not support delineation of deny the petition to consider this DPS not solicit comments on it. the Saint John River population segment for delisting. Our denial of the petition on this ground does not imply any References Cited as ‘‘significant.’’ In so interpreting the available genetic data, we are mindful of finding as to how we should proceed if A complete list of references is the Congressional guidance to use the the situation were otherwise, i.e., where available upon request to the Office of DPS designation sparingly. a population is found instead to meet Protected Resources (see ADDRESSES). the criteria to be a DPS. Even if the DPS Conclusion and Petition Finding population had met both criteria of the Authority We conclude that the Saint John River DPS Policy, and even if the population The authority for this action is the population of shortnose sturgeon is were also found to have a status that Endangered Species Act of 1973, as ‘‘discrete’’ based on evidence that it is differed from the listed entity, it would amended (16 U.S.C. 1531 et seq.). a relatively closed and somewhat not necessarily be appropriate to geographically isolated population propose modifications to the current Dated: October 20, 2015. segment. It thus satisfies the first prong listing, in light of the unsettled legal Samuel D. Rauch III, of the DPS policy. However, we also issues surrounding such revisions. Nor Deputy Assistant Administrator for find that the Saint John River do we resolve here what steps would Regulatory Programs, National Marine population segment is not ‘‘significant’’ need to be followed to propose revisions Fisheries Service. to the taxon as a whole. It thus fails to to the species’ listing if the facts had [FR Doc. 2015–27148 Filed 10–23–15; 8:45 am] satisfy the second prong of the DPS been otherwise; such an inquiry would BILLING CODE 3510–22–P asabaliauskas on DSK5VPTVN1PROD with PROPOSALS VerDate Sep<11>2014 18:00 Oct 23, 2015 Jkt 238001 PO 00000 Frm 00026 Fmt 4702 Sfmt 9990 E:\FR\FM\26OCP1.SGM 26OCP1$

Document Created: 2018-02-27 08:56:19
Document Modified: 2018-02-27 08:56:19

Category		Regulatory Information
Collection		Federal Register
sudoc Class		AE 2.7: GS 4.107: AE 2.106:
Publisher		Office of the Federal Register, National Archives and Records Administration
Section		Proposed Rules
Action		Notice of 12-month petition finding.
Dates		This finding was made on October 26, 2015.
Contact		Lisa Manning, Office of Protected Resources, 301-427-8466; Stephania Bolden, Southeast Regional Office, 727-824-5312; Julie Crocker, Greater Atlantic Regional Office, 978-282- 8480.
FR Citation		80 FR 65183
RIN Number		0648-XD76

80 FR 65183 - Endangered and Threatened Wildlife; 12-Month Finding on a Petition To Identify and Delist a Saint John River Distinct Population Segment of Shortnose Sturgeon Under the Endangered Species Act

DEPARTMENT OF COMMERCENational Oceanic and Atmospheric Administration

Federal Register Volume 80, Issue 206 (October 26, 2015)

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration