Endangered and Threatened Wildlife and Plants; Proposed Listing Determinations for Three Distinct Population Segments of Atlantic Sturgeon in the Northeast Region, 61872-61904 [2010-24459]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 75, Number 193 (Wednesday, October 6, 2010)]
[Proposed Rules]
[Pages 61872-61904]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-24459]



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Part II





Department of Commerce





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National Oceanic and Atmospheric Administration



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50 CFR Parts 223 and 224



Endangered and Threatened Wildlife and Plants; Proposed Rules

Federal Register / Vol. 75, No. 193 / Wednesday, October 6, 2010 / 
Proposed Rules

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Parts 223 and Part 224

RIN 0648-XJ00
[Docket No. 100903414-0414-02]


Endangered and Threatened Wildlife and Plants; Proposed Listing 
Determinations for Three Distinct Population Segments of Atlantic 
Sturgeon in the Northeast Region

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

ACTION: Proposed rule; request for comments.

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SUMMARY: We, NMFS, have completed an Endangered Species Act (ESA) 
status review for Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus). 
Based on the status review report (ASSRT, 2007), and other information 
available since completion of the status review report, we have 
determined that the species is comprised of five distinct population 
segments (DPSs) that qualify as species under the ESA: Gulf of Maine 
(GOM); New York Bight (NYB); Chesapeake Bay (CB); Carolina; and South 
Atlantic. We have also determined that, for those DPSs that are located 
within the jurisdiction of NMFS' Northeast Region, listing as 
threatened is warranted for the GOM DPS, and listing as endangered is 
warranted for the NYB DPS and CB DPS. A separate proposed listing 
determination is issued for the two DPSs within NMFS' Southeast Region 
in today's Federal Register.

DATES: Comments on this proposal must be received by January 4, 2011. 
At least one public hearing will be held in a central location for each 
DPS; notice of the locations and times of the hearings will be 
published in the Federal Register not less than 15 days before the 
hearings are held.

ADDRESSES: You may submit comments, identified by the RIN 0648-XJ00, by 
any of the following methods:
     Federal eRulemaking Portal: http//www.regulations.gov. 
Follow the instructions for submitting comments.
     Fax: To the attention of Lynn Lankshear at (978) 281-9394.
     Mail or hand-delivery: Submit written comments to the 
Assistant Regional Administrator, Protected Resources Division, NMFS, 
Northeast Region, 55 Great Republic Drive, Gloucester, MA 01930.
    Instructions:
    All comments received are a part of the public record and will 
generally be posted to https://www.regulations.gov without change. All 
Personal Identifying Information (for example, name, address, etc.) 
voluntarily submitted by the commenter may be publicly accessible. Do 
not submit Confidential Business Information or otherwise sensitive or 
protected information.
    We will accept anonymous comments (enter ``n/a'' in the required 
fields if you wish to remain anonymous). Attachments to electronic 
comments will be accepted in Microsoft Word, Excel, WordPerfect, or 
Adobe PDF file formats only.
    The proposed rule, status review report, and other reference 
materials regarding this determination are available electronically at 
the following Web site at https://www.nero.noaa.gov/prot_res/CandidateSpeciesProgram/cs.htm or by submitting a request to the 
Assistant Regional Administrator, Protected Resources Division, NMFS, 
Northeast Region, 55 Great Republic Drive, Gloucester, MA 01930.

FOR FURTHER INFORMATION CONTACT: Lynn Lankshear, NMFS, Northeast Region 
(978) 282-8473; Kimberly Damon-Randall, NMFS, Northeast Region (978) 
282-8485; or Marta Nammack, NMFS, Office of Protected Resources (301) 
713-1401.

SUPPLEMENTARY INFORMATION: 

Public Comments Solicited

    We solicit scientific and commercial information to inform the 
listing determinations for the GOM, NYB, and CB DPSs to ensure that the 
final action resulting from this proposal considers information that is 
comprehensive and current. We particularly seek comments concerning: 
information on the abundance and distribution of Atlantic sturgeon 
belonging to the GOM, NYB, and/or the CB DPSs; information concerning 
the viability of and/or threats to Atlantic sturgeon belonging to the 
GOM, NYB, and/or the CB DPSs; efforts being made to protect Atlantic 
sturgeon belonging to the GOM, NYB, or CB DPSs; and the mixing of fish 
from different DPSs in parts of their ranges, particularly the marine 
environment.
    We are not proposing critical habitat for the GOM, NYB, or CB DPSs 
at this time, given that further analysis of GIS mapping data is 
necessary for determining the critical habitat of each of the three 
DPSs. Therefore, we will propose to designate critical habitat for each 
DPS in a separate Federal Register notification once analysis of the 
data is complete. If the proposed listing is finalized, a recovery plan 
will be prepared for each DPS. In addition, any protective regulations 
determined to be necessary and advisable for the conservation of the 
GOM DPS under ESA section 4(d) will be proposed in a subsequent Federal 
Register document.

Background

    There are two subspecies of Atlantic sturgeon--Acipenser oxyrinchus 
oxyrinchus, which is commonly referred to as Atlantic sturgeon, and 
Acipenser oxyrinchus desotoi, commonly referred to as Gulf sturgeon. 
This proposed rule addresses the subspecies Acipenser oxyrinchus 
oxyrinchus (hereafter referred to as Atlantic sturgeon), which is 
distributed along the eastern coast of North America.

Listing Species Under the Endangered Species Act

    We, NMFS, are responsible for determining whether Atlantic sturgeon 
are threatened or endangered under the ESA (16 U.S.C. 1531 et seq.). 
Accordingly, based on the statutory, regulatory, and policy provisions 
described below, the steps we followed in making our listing 
determination for Atlantic sturgeon were to: (1) Determine how Atlantic 
sturgeon meet the definition of ``species''; (2) determine the status 
of the species and the factors affecting it; and (3) identify and 
assess efforts being made to protect the species and determine if these 
efforts are adequate to mitigate existing threats.
    To be considered for listing under the ESA, a group of organisms 
must constitute a ``species.'' A ``species'' is defined in section 3 of 
the ESA 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.'' On February 7, 1996, the NMFS 
and U.S. Fish and Wildlife Service (collectively the ``Services'') 
adopted a policy to clarify our interpretation of the phrase ``distinct 
population segment of any species of vertebrate fish or wildlife'' (61 
FR 4722). The joint DPS policy describes two criteria that must be 
considered when identifying DPSs: (1) The discreteness of the 
population segment in relation to the remainder of the species (or 
subspecies) to which it belongs; and (2) the significance of the 
population segment to the remainder of the species (or subspecies) to 
which it belongs. As further stated in the joint policy, if a 
population segment is discrete and significant (i.e., it meets the DPS 
policy criteria), its evaluation for endangered or threatened status 
will be based on the ESA's definition of those terms and a

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review of the five factors enumerated in section 4(a)(1) of the ESA.
    The ESA defines an endangered species as ``any species which is in 
danger of extinction throughout all or a significant portion of its 
range'' and a threatened species as one ``which is likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' As provided in section 4(a) of the 
ESA, the statute requires us to determine whether any species is 
endangered or threatened because of any of the following five factors: 
(1) The present or threatened destruction, modification, or curtailment 
of its habitat or range; (2) overutilization for commercial, 
recreational, scientific, or educational purposes; (3) disease or 
predation; (4) the inadequacy of existing regulatory mechanisms; or (5) 
other natural or manmade factors affecting its continued existence 
(section 4(a)(1)(A)(E)).
    Section 4(b)(1)(A) of the ESA further requires that listing 
determinations be based solely on the best scientific and commercial 
data available after taking into account efforts being made to protect 
the species. In judging the efficacy of existing protective efforts, we 
rely on the Service's joint ``Policy for Evaluation of Conservation 
Efforts When Making Listing Decisions'' (``PECE''; 68 FR 15100; March 
28, 2003). The PECE provides direction for consideration of 
conservation efforts that have not been implemented, or have been 
implemented but not yet demonstrated effectiveness.

Status Review

    We first identified Atlantic sturgeon as a candidate species in 
1991; at that time, the candidate species list served to notify the 
public that we had concerns regarding these species that may warrant 
listing in the future, and it facilitated voluntary conservation 
efforts. On June 2, 1997, the Services received a petition from the 
Biodiversity Legal Foundation requesting that we list Atlantic sturgeon 
in the United States as threatened or endangered and designate critical 
habitat within a reasonable period of time following the listing. A 
notice was published in the Federal Register on October 17, 1997, 
stating that the Services had determined substantial information 
existed indicating the petitioned action may be warranted (62 FR 
54018). In 1998, after completing a comprehensive status review, the 
Services published a 12-month determination in the Federal Register, 
announcing that listing was not warranted at that time (63 FR 50187; 
September 21, 1998). We retained Atlantic sturgeon on the candidate 
species list (subsequently changed to the Species of Concern List (69 
FR 19975; April 15, 2004)).
    Concurrently, the Atlantic States Marine Fisheries Commission 
(ASMFC) completed Amendment 1 to the 1990 Atlantic Sturgeon Fishery 
Management Plan (FMP) that imposed a 20-40 year moratorium on all 
Atlantic sturgeon fisheries until the Atlantic Coast spawning stocks 
could be restored to a level where 20 subsequent year classes of adult 
females were protected (ASMFC, 1998). In 1999, pursuant to section 
804(b) of the Atlantic Coastal Fisheries Cooperative Management Act 
(ACFCMA) (16 U.S.C. 5101 et seq.), we followed this action by closing 
the Exclusive Economic Zone (EEZ) to Atlantic sturgeon retention. In 
2003, we sponsored a workshop with the U.S. Fish and Wildlife Service 
(FWS) and the ASMFC entitled ``Status and Management of Atlantic 
Sturgeon,'' to discuss the status of Atlantic sturgeon along the 
Atlantic Coast and determine what obstacles, if any, were impeding 
their recovery (Kahnle et al., 2005). The results of the workshop 
indicated some river populations (hereafter referred to as 
``subpopulations'') seemed to be recovering while others were 
declining. Bycatch and habitat degradation were noted as possible 
causes for continued declines.
    Based on the information gathered from the 2003 workshop on 
Atlantic sturgeon, we decided that a second review of Atlantic sturgeon 
status was needed to determine if listing as endangered or threatened 
under the ESA was warranted. We, therefore, established a status review 
team (SRT) consisting of NMFS, FWS, and U.S. Geological Survey (USGS) 
scientists with relevant expertise to assist us in assessing the 
viability of the species throughout all or a significant portion of its 
range. The SRT was asked to consider the best scientific and commercial 
information available, including the technical information and comments 
from state and regional experts. The draft status review report 
prepared by the SRT was peer reviewed by experts from academia, and 
their comments were incorporated. A Notice of Availability of this 
report was published in the Federal Register on April 3, 2007 (72 FR 
15865).
    On October 6, 2009, we received a petition from the Natural 
Resources Defense Council to list Atlantic sturgeon as endangered under 
the ESA. As an alternative, the petitioner requested that the species 
be delineated and listed as the five DPSs described in the 2007 
Atlantic sturgeon status review (ASSRT, 2007) (i.e., Gulf of Maine, New 
York Bight, Chesapeake Bay, Carolina, and South Atlantic DPSs), with 
the Gulf of Maine and South Atlantic DPSs listed as threatened, and the 
remaining three DPSs listed as endangered. The petitioner also 
requested that critical habitat be designated for Atlantic sturgeon 
under the ESA. We published a Notice of 90-Day Finding on January 6, 
2010 (75 FR 838), stating that the petition presented substantial 
scientific or commercial information indicating that the petitioned 
actions may be warranted.
    The status review report upon which this proposed rule is based 
provides extensive information on Atlantic sturgeon biology, life 
history, distribution, and abundance to support its conclusions. A 
summary of this information is provided below. More detailed 
information is available in the status review report.

Biology and Life History of Atlantic Sturgeon

    Atlantic sturgeon are distinguished by armor-like plates and a long 
snout with a ventrally located protruding mouth. Four barbels crossing 
in front of the mouth help the sturgeon to locate prey. Sturgeon are 
omnivorous benthic feeders (feed off the bottom) and filter quantities 
of mud along with their food. Adult sturgeon diets include mollusks, 
gastropods, amphipods, isopods, and fish. Juvenile sturgeon feed on 
aquatic insects and other invertebrates (ASSRT, 2007).
    The general life history pattern of Atlantic sturgeon is that of a 
long lived (approximately 60 years; Mangin, 1964; Stevenson and Secor, 
1999), late maturing, estuarine dependent, anadromous species (ASSRT, 
2007). They can reach lengths up to 14 feet (4.26 m), and weigh over 
800 pounds (~364 kg).
    Fecundity of female Atlantic sturgeon has been correlated with age 
and body size, with observed egg production ranging from 400,000 to 4 
million eggs per spawning year (Smith et al., 1982; Van Eenennaam et 
al., 1996; Van Eenennaam and Doroshov, 1998; Dadswell, 2006). Female 
gonad weight varies from 12-25 percent of the total body weight (Smith, 
1907; Huff, 1975; Dadswell, 2006). Therefore, the fecundity of a 770-
pound (350 kg) female, like the one captured in the St. John River, 
Canada, in 1924, could be 7-8 million eggs (Dadswell, 2006). The 
average age at which 50 percent of the maximum lifetime egg production 
is achieved is estimated to be 29 years (Boreman, 1997).
    Atlantic sturgeon likely do not spawn every year. Multiple studies 
have shown

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that spawning intervals range from 1-5 years for males (Smith, 1985; 
Collins et al., 2000; Caron et al., 2002) and 2-5 years for females 
(Vladykov and Greeley, 1963; Van Eenennaam et al., 1996; Stevenson and 
Secor, 1999). Spawning behavior also differs between the sexes. While 
there is a window of time for each river during which spawning occurs, 
spawning females do not migrate upstream together. Individual females 
make rapid spawning migrations upstream and quickly depart following 
spawning (Bain, 1997). Spawning males usually arrive on the spawning 
grounds before any of the females have arrived and leave after the last 
female has spawned (Bain, 1997). Presumably, this provides an 
opportunity for a single male to fertilize eggs of multiple females.
    Spawning is believed to occur in flowing water between the salt 
front of estuaries and the fall line of large rivers, where optimal 
flows are 46-76 cm/s and depths are 11-27 m (Borodin, 1925; Leland, 
1968; Scott and Crossman, 1973; Crance, 1987; Bain et al., 2000). 
Sturgeon eggs are highly adhesive and are deposited on the bottom 
substrate, usually on hard surfaces such as cobble (Gilbert, 1989; 
Smith and Clugston, 1997). Hatching occurs approximately 94 and 140 
hours after egg deposition at temperatures of 20[deg] and 18 [deg]C, 
respectively, and, once hatched, larvae assume a demersal existence 
(Smith et al., 1980). The yolksac larval stage is completed in about 8-
12 days, during which time the larvae move downstream to the rearing 
grounds (Kynard and Horgan, 2002). During the first half of this 
migration, larvae move only at night and use benthic structure (e.g., 
gravel matrix) as refuge during the day (Kynard and Horgan, 2002). 
During the latter half of migration to the rearing grounds, when larvae 
are more fully developed, movement occurs during both day and night. 
Larvae transition into the juvenile phase as they continue to move even 
further downstream into brackish waters, developing a tolerance to 
salinity as they go, and eventually become residents in estuarine 
waters for months to years before emigrating to open ocean as subadults 
(Holland and Yelverton, 1973; Doevel and Berggen, 1983; Waldman et al., 
1996a; Dadswell, 2006; ASSRT, 2007).
    Atlantic sturgeon that originate from different rivers demonstrate 
differences in growth rate, maturation, and timing of spawning. For 
example, Atlantic sturgeon mature in South Carolina river systems at 5 
to 19 years (Smith et al., 1982), in the Hudson River at 11 to 21 years 
(Young et al., 1998), and in the Saint Lawrence River at 22 to 34 years 
(Scott and Crossman, 1973). In general, Atlantic sturgeon 
subpopulations show clinal variation with faster growth and earlier age 
at maturation for fish originating from more southern systems, though 
not all data sets conform to this trend. Timing of spawning migrations 
also exhibit a latitudinal pattern in which migrations generally occur 
during February-March in southern systems, April-May in mid-Atlantic 
systems, and May-July in Canadian systems (Murawski and Pacheco, 1977; 
Smith, 1985; Bain, 1997; Smith and Clugston, 1997; Caron et al., 2002). 
In some rivers, predominantly in the south, a fall spawning migration 
may also occur (Rogers and Weber, 1995; Weber and Jennings, 1996; Moser 
et al., 1998).

Distribution and Abundance

    Historically, Atlantic sturgeon were present in approximately 38 
rivers in the United States from St. Croix, ME, to the Saint Johns 
River, FL, 35 of which have been confirmed to have supported spawning 
for Atlantic sturgeon (ASSRT, 2007). It is unknown how many Canadian 
rivers were historically used by Atlantic sturgeon. However, it is 
likely that Atlantic sturgeon spawn(ed) in the Miramichi, Shubenacadie, 
Avon, Annapolis, and in other systems of similar size in addition to 
the presently known subpopulations that spawn in the Saint Lawrence 
River and Saint John River (reviewed in Dadswell, 2006; ASSRT, 2007). 
Overall, historical sightings of Atlantic sturgeon were generally 
reported from Hamilton Inlet, Labrador, south to the Saint Johns River, 
Florida (Murawski and Pacheko, 1977; Smith and Clugston, 1997; ASSRT, 
2007). Occurrences south of the Saint Johns River, Florida, and north 
of Hamilton Inlet, Labrador, may have always been rare.
    It is clear that Atlantic sturgeon underwent significant range-wide 
declines from historical abundance levels due to overfishing (reviewed 
in Smith and Clugston, 1997). Although Atlantic sturgeon had been 
previously exploited in commercial fisheries (Scott and Crossman, 1973; 
Taub, 1990; Dadswell, 2006; ASSRT, 2007), records from the 1700s and 
1800s document large numbers of sturgeon in many rivers along the 
Atlantic coast (Kennebec River Resource Management Plan, 1993; 
Armstrong and Hightower, 2002). However, in 1870, a significant fishery 
for the species developed when a caviar market was established. Record 
landings were reported in 1890, when over 3,350 metric tons (mt) of 
Atlantic sturgeon were landed from coastal rivers along the Atlantic 
Coast (reviewed in Smith and Clugston, 1997; Secor and Waldman, 1999). 
The fishery collapsed in 1901, 10 years after peak landings, when less 
than 10 percent (295 mt) of its 1890 peak landings were reported. 
During the 1950s, the remaining fishery switched to targeting sturgeon 
for flesh, rather than caviar. Commercial fisheries were active in many 
rivers during all or some of the period from 1962 to 1997, albeit at 
much lower levels than in the late 1800s--early 1900s (Taub, 1990; 
Smith and Clugston, 1997). Nevertheless, many of these contemporary 
fisheries also resulted in overfishing, which prompted the ASMFC to 
impose the 1998 coastwide moratorium for fisheries targeting Atlantic 
sturgeon and NMFS to close the EEZ to Atlantic sturgeon retention in 
1999.
    Currently, Atlantic sturgeon presence is documented in 36 rivers in 
the United States and Canada, combined (ASSRT, 2007; J. Sulikowski, 
UNE, pers. comm.). At least 18 rivers are believed to support spawning 
based on available evidence (i.e., presence of young-of-year or gravid 
Atlantic sturgeon documented within the past 15 years) (ASSRT, 2007). 
These rivers are: Saint Lawrence, QB; Annapolis, NS; Saint John, NB; 
Kennebec, ME; Hudson, NY; Delaware, NJ/DE/PA; James, VA; Roanoke, NC; 
Tar-Pamlico, NC; Cape Fear, NC; Waccamaw, SC; Great PeeDee, SC; 
Combahee, SC; Edisto, SC; Savannah, SC/GA; Ogeechee, GA; Altamaha, GA; 
and, the Satilla, GA (ASSRT, 2007). Rivers with possible, but 
unconfirmed, spawning include: St Croix, NB/ME; Penobscot, 
Androscoggin, and Sheepscot, ME, York, VA; Neuse, NC; Santee and Cooper 
Rivers; spawning may occur in the Santee and/or the Cooper Rivers, but 
it may not result in successful recruitment (ASSRT, 2007).
    Comprehensive information on current abundance of Atlantic sturgeon 
is lacking for any of the spawning rivers (ASSRT, 2007). In the United 
States, an estimate of 870 spawning adults/year is available for the 
Hudson River (Kahnle et al., 2007). An estimate of 343 spawning adults/
year is available for the Altamaha River, GA, based on data collected 
in 2004-2005 (Schueller and Peterson, 2006). Data collected from the 
Hudson River and Altamaha River studies cannot be used to estimate the 
total number of adults in either subpopulation, since mature Atlantic 
sturgeon may not spawn every year (Vladykov and Greeley, 1963; Smith, 
1985; Van Eenennaam et al., 1996; Stevenson and Secor, 1999; Collins et 
al. 2000; Caron et al., 2002), and it is unclear to what extent mature 
fish in a non-spawning condition occur on the

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spawning grounds. Nevertheless, since the Hudson and Altamaha rivers 
are presumed to have the healthiest Atlantic sturgeon subpopulations 
within the United States, other U.S. subpopulations are predicted to 
have fewer spawning adults than either the Hudson or the Altamaha 
(ASSRT, 2007). In Canada, an estimate of spawning size is available for 
the Saint Lawrence River where tagging work suggests a total spawning 
subpopulation of over 500 adults (Caron et al., 2002; Dadswell, 2006).
    Surveys and other programs (e.g., reward programs) have provided 
more qualitative information on Atlantic sturgeon subpopulations. While 
these programs may not have sufficient information by which to generate 
any subpopulation estimate(s), they do provide some river-specific 
information on abundance, trends, evidence of spawning, and/or 
documentation of multiple-year classes. For example, a multi-filament 
gill net survey conducted intermittently in the Kennebec River from 
1977-2000 captured 336 Atlantic sturgeon (9 adults and 327 subadults) 
(Squiers, 2004). During this period, the catch-per-unit effort (CPUE) 
of subadult Atlantic sturgeon increased by a factor of 10-25 (1977-1981 
CPUE = 0.30 versus 1998-2000 CPUE = 7.43). The CPUE of adult Atlantic 
sturgeon showed a slight increase over the same time period (1977-1981 
CPUE = 0.12 versus 1998-2000 CPUE = 0.21) (Squiers, 2004).
    An intensive gill net survey was conducted in the Merrimack River 
from 1987-1990 to determine annual movements, spawning, summering, and 
wintering areas of shortnose and Atlantic sturgeon (Kieffer and Kynard, 
1993). Thirty-six Atlantic sturgeon were captured (70-156 cm total 
length (TL)); most were under 100 cm TL, suggesting that these were all 
subadult sturgeon (Kieffer and Kynard, 1993).
    In Delaware, gill net surveys are conducted on the Delaware River 
by the state's Division of Fish and Wildlife as part of their Atlantic 
Sturgeon Research program. Since 1991, more than 2,000 Atlantic 
sturgeon have been captured and tagged (DNREC, 2009). Based on their 
length, most are believed to have been subadults. In September 2009, 
however, personnel captured their smallest sturgeon yet; an age 0 fish, 
which was 7 inches TL (178 mm) and weighed less than an ounce (DNREC, 
2009). In all, 34 young-of-year (YOY) sturgeon were caught during the 
sampling period (September 9-November 9, 2009), ranging in size from 
178 to 349 mm TL (Fisher, 2009). These captures provide evidence that 
successful spawning is still occurring in the Delaware River.
    Within the Chesapeake Bay, the FWS has been funding the Maryland 
Reward Program since 1996; this program has resulted in the 
documentation of approximately 1,700 Atlantic sturgeon. Five hundred 
and sixty-seven of these fish were hatchery fish, of which 462 were 
first time captures (14 percent recapture rate), and the remaining 
captures (1,133) were wild fish.
    Virginia also instituted an Atlantic sturgeon reward program in the 
Chesapeake Bay in 1997 and 1998 (ASSRT, 2007; A. Spells, FWS, pers. 
comm., 2008). This reward program documented and measured 295 Atlantic 
sturgeon. Data collected during the reward program documents the 
presence of YOY fish. Such data include length information which shows 
that 18.6 percent (55 of 295 measured) of the fish caught were within 
the 20 to 40 cm fork length size class (A. Spells, FWS, pers. comm., 
2008). In addition, aging of fish spines collected from the fish 
suggested that 34 percent were age 1 (A. Spells, FWS, pers. comm., 
2008). This information is important in that it strongly suggests the 
presence of spawning in one or more rivers that flow into the Bay. 
Further evidence of Atlantic sturgeon spawning in the Chesapeake Bay 
area is provided by three carcasses of large adults found in the James 
River in 2000-2003; the discovery of a 213 cm TL carcass of an adult 
found in the Appomattox River in 2005; the capture and release of a 240 
cm TL Atlantic sturgeon near Hoopers Island, MD in April, 1998 (S. 
Minkkinen, FWS, pers. comm., 2006); documentation of a gravid adult 
female Atlantic sturgeon off Tilghman Island, MD in April, 2007 (the 
first gravid female documented in the Maryland portion of the 
Chesapeake Bay since the early 1970s); and the capture of several males 
producing milt (sperm) in the James River in 2007 and 2008 (A. Spells, 
FWS, pers. comm.).

Identification of Distinct Population Segments

    As described above, the ESA's definition of ``species'' includes 
``any subspecies of fish or wildlife or plants, and any distinct 
population segment of any species or vertebrate fish or wildlife which 
interbreeds when mature.'' As previously described, Atlantic sturgeon 
originating from different rivers are known to co-occur in the marine 
environment and use multiple river systems for life functions, such as 
foraging. The DPS policy does not require absolute separation of a DPS 
from other members of its species (61 FR 4722; February 7, 1996). The 
high degree of reproductive isolation of Atlantic sturgeon (i.e., 
homing to their natal rivers for spawning) (K. Hattala,, NYDEC, pers. 
comm., 1998; Wirgin et al., 2000; King et al., 2001; Waldman et al., 
2002) as well as the ecological uniqueness of those riverine spawning 
habitats and the genetic diversity among subpopulations, provides 
evidence that several populations meet the DPS Policy criteria. 
Therefore, prior to evaluating the conservation status for Atlantic 
sturgeon, and in accordance with the joint DPS policy, we considered: 
(1) The discreteness of any Atlantic sturgeon population segment in 
relation to the remainder of the subspecies to which it belongs; and 
(2) the significance of any Atlantic sturgeon population segment to the 
remainder of the subspecies to which it belongs.

Discreteness

    The joint DPS policy states that a population 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); or (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.
    As has already been discussed, adult and subadult Atlantic sturgeon 
which originate from different rivers mix in the marine environment 
(Stein et al., 2004; USFWS, 2004). Nevertheless, there is marked 
separation of Atlantic sturgeon as a result of both spatial and 
temporal separation of reproduction among river subpopulations. Tagging 
studies and genetic analyses provide evidence that Atlantic sturgeon 
return to their natal rivers for spawning (K. Hattala, NYDEC, pers. 
comm., 1998; Wirgin et al., 2000; King et al., 2001; Waldman et al., 
2002). As previously mentioned, Atlantic sturgeon are temporally 
separated with respect to spawning, since all adults are not 
reproductively active at the same time within each year (Murawski and 
Pacheco, 1977; Smith, 1985; Rogers and Weber, 1995; Bain, 1997; Smith 
and Clugston, 1997; Moser et al., 1998; Caron et al., 2002). For 
example, Atlantic sturgeon spawn in the Hudson River in May through 
July (Bain, 1997), while spawning in the St. Lawrence

[[Page 61876]]

River occurs in June through July (Caron et al., 2002).
    The SRT also considered genetics data to further inform its 
decisions as to whether there is discreteness amongst Atlantic sturgeon 
subpopulations. Genetics analyses for Atlantic sturgeon using 
mitochondrial DNA (mtDNA), which is maternally inherited, and nuclear 
DNA (nDNA), which reflects the genetics of both parents, have 
consistently shown that Atlantic sturgeon subpopulations are 
genetically diverse and that individual subpopulations can be 
differentiated (Bowen and Avise, 1990; Ong et al., 1996; Waldman et 
al., 1996a; Waldman et al., 1996b; Waldman and Wirgin, 1998; Waldman et 
al., 2002; King et al., 2001; Wirgin et al., 2002; Wirgin et al., 2005; 
Wirgin and King supplemental data, 2006; Grunwald et al., 2008). New 
analyses of both mtDNA and nDNA were conducted specifically for the 
status review. In comparison to previous studies, the genetic analyses 
for the status review employed greater sample sizes from multiple 
rivers, and limited the samples analyzed to those collected from YOY 
and mature adults (> 130 cm TL) to ensure that the fish originated from 
the river in which it was sampled (Wirgin and King supplemental data, 
2006; ASSRT, 2007). The results for both the mtDNA haplotype and 
microsatellite (nDNA) allelic frequencies indicated that all of the 
Atlantic sturgeon subpopulations for which there are samples available 
are genetically differentiated (ASSRT, 2007; Tables 4 and 5) from each 
other. The results of the mtDNA analysis used for the status review 
report were also subsequently published by Grunwald et al. (2008). In 
comparison to the mtDNA analyses used for the status review report, 
Grunwald et al. used additional samples, some from fish in the size 
range (< 130 cm TL) excluded by Wirgin and King (supplemental data, 
2006) because they were smaller than those considered to be mature 
adults. Nevertheless, the results were the same and demonstrated that 
each of the 12 sampled Atlantic sturgeon subpopulations could be 
genetically differentiated from each other (Grunwald et al., 2008).
    Genetic distances and statistical analyses (bootstrap values and 
assignment test values) were also used to investigate significant 
relationships among, and differences between, Atlantic sturgeon 
subpopulations (ASSRT, 2007, Table 6 and Figures 16-18). Overall, the 
genetic markers used in this analysis resulted in an average accuracy 
of 88 percent for determining a sturgeon's natal river origin, but an 
average accuracy of 94 percent for correctly classifying it to one of 
five population groups (Kennebec River, Hudson River, James River, 
Albemarle Sound, and Savannah/Ogeechee/Altamaha Rivers) when using 
microsatellite data collected only from YOY and adults. A phylogenetic 
tree (neighbor joining tree) was produced from only YOY and adult 
samples (to reduce the likelihood of including strays from other 
subpopulations) using the microsatellite analysis. Bootstrap values 
(which measure how consistently the data support the tree structure) 
for this tree were for analyses of: (1) 12 loci of samples collected 
from YOY and adults; and (2) 7 loci for samples of YOY, subadult, and 
adult Atlantic sturgeon (ASSRT, 2007, Figures 16-18). Classification 
success rate averaged 79.0 percent for determining a sturgeon's natal 
river and 86.9 percent for correctly classifying sturgeon to one of 
five population groups (Kennebec River, Hudson River, James River, 
Albemarle Sound, and Savannah/Ogeechee/Altamaha Rivers) (ASSRT, 2007). 
Regarding sturgeon from northeast rivers, this analysis resulted in a 
range of 81 to 89 percent accuracy in determining a sturgeon's natal 
river of origin and correctly classifying a sturgeon to a population 
group. To further assess the accuracy of the results, King 
(supplemental data, 2006) reanalyzed the nDNA using a greater number of 
loci. His results showed that increasing the number of loci from 7 to 
12 improved the classification rates for natal origin and 
identification of population groupings (e.g., from 84 percent to 95 
percent for the James River), but did not change the conclusion that 
there are five discrete Atlantic sturgeon population segments in the 
United States.
    In summary, evidence to support that there are discrete Atlantic 
sturgeon populations includes temporal and spatial separation during 
spawning and the results from genetic analyses. Genetic samples for YOY 
and spawning adults were not available for river populations 
originating from other rivers in the northeast region. However, nDNA 
from an expanded dataset that included juvenile Atlantic sturgeon was 
used to produce a neighbor-joining tree with bootstrap values (ASSRT, 
2007; Figure 18). This dataset included additional samples from the 
Delaware River and York River populations in the Northeast. Atlantic 
sturgeon river populations also grouped into five population segments 
in this analysis (Delaware River population with the Hudson River 
population, and York River population with the James River population).
    We have considered the information on Atlantic sturgeon population 
structuring provided in the status review report and Grunwald et al. 
(2008) and have concluded that five discrete Atlantic sturgeon 
population segments are present in the United States, with three 
located in the Northeast: (1)--The ``Gulf of Maine (GOM)'' population 
segment, which includes Atlantic sturgeon that originate from the 
Kennebec River, (2)--the ``New York Bight (NYB)'' population segment, 
which includes Atlantic sturgeon originating from the Hudson and 
Delaware Rivers, and (3)--the ``Chesapeake Bay (CB)'' population 
segment, which includes Atlantic sturgeon that originate from the James 
and York Rivers. Each is markedly separate from the other four 
population segments as a consequence of physical factors.
    With respect to Atlantic sturgeon of Canadian origin, mtDNA 
analysis has shown that Atlantic sturgeon originating from rivers 
ranging from the Kennebec River, Maine, to the Saint Lawrence River, 
Canada, are predominately homogenous (one genotype) (Waldman et al., 
2002; Grunwald et al., 2008; ASSRT, 2007). However, nDNA microsatellite 
analysis has found these same rivers to be genetically diverse (King, 
supplemental data, 2006). The SRT concluded that the differences in 
nDNA were sufficient to determine that Atlantic sturgeon which 
originate in Canada are markedly separate from Atlantic sturgeon of 
U.S. origin.
    The genetic analyses support that at least one, and possibly more, 
discrete Atlantic sturgeon population groupings occur in Canada. The 
SRT did not further consider the status of Atlantic sturgeon 
originating in Canada once it was determined that they were discrete 
from the five U.S. Atlantic sturgeon population groupings. We did not 
consider a listing determination for these populations given the lack 
of information by which to determine whether the Canadian 
subpopulations represent one or more DPSs, and given the regulatory 
controls on import and export of Atlantic sturgeon and their parts per 
the Convention on International Trade in Endangered Species of Wild 
Flora and Fauna (CITES).

Significance

    When the discreteness criterion is met for a potential DPS, as it 
is for the GOM, NYB, and CB population segments in the Northeast 
identified above, the second element that must be considered

[[Page 61877]]

under the DPS policy is significance of each DPS to the taxon as a 
whole. The DPS policy cites examples of potential considerations 
indicating significance, including: (1) Persistence of the discrete 
population segment in an ecological setting unusual or unique for the 
taxon; (2) evidence that loss of the discrete population segment would 
result in a significant gap in the range of the taxon; (3) evidence 
that the DPS represents the only surviving natural occurrence of a 
taxon that may be more abundant elsewhere as an introduced population 
outside its historic range; or, (4) evidence that the discrete 
population segment differs markedly from other populations of the 
species in its genetic characteristics.
    We believe that the five discrete Atlantic sturgeon population 
segments persist in ecological settings unique for the taxon. This is 
evidenced by the fact that spawning habitat of each population grouping 
is found in separate and distinct ecoregions that were identified by 
The Nature Conservancy (TNC) based on the habitat, climate, geology, 
and physiographic differences for both terrestrial and marine 
ecosystems throughout the range of the Atlantic sturgeon along the 
Atlantic coast (Figure 1).
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    TNC descriptions do not include detailed information on the 
chemical properties of the rivers within each ecoregion, but include an 
analysis of bedrock and surficial geology type because it relates to 
water chemistry, hydrologic regime, and substrate. It is well 
established that waters have different chemical properties (i.e., 
identities) depending on the geology of where the waters originate. For 
example, riverine spawning/nursery habitat of the Kennebec River 
subpopulation occurs within the Northern Appalachian/Boreal Forest 
ecoregion whose characteristically large expanses of forest, variety of 
swamps, marshes, bogs, ice scoured riverbanks, salt marshes, and rocky 
coastal cliffs were influenced by a geological history that includes 
four glaciation events (TNC, 2008). In contrast, riverine spawning/
nursery habitat of Atlantic sturgeon that originate from the Hudson and 
Delaware Rivers occurs within the Lower New England-Northern Piedmont 
and North Atlantic Coast ecoregions which are characterized by low 
mountains, abundant lakes, and limestone valleys inland and generally

[[Page 61879]]

flat, sandy coastal plains dissected by major tidal river systems near 
the coast (Barbour, 2000; TNC, 2008). The Chesapeake Bay Lowlands 
ecoregion, within which riverine spawning/nursery habitat for the James 
River population grouping of Atlantic sturgeon occurs, presents yet a 
different landscape based on its geologic history. As glaciers that 
extended as far south as present day Pennsylvania began to melt, 
streams and rivers that flowed toward the coast were carved out of the 
landscape (Pyzik et al., 2004). These past events are seen today in the 
characteristic features of the Chesapeake Bay Lowlands ecoregion which 
includes a broad plain to the west of the Bay with generally low slopes 
and gentle drainage dissected by a series of major rivers--the 
Patuxent, Potomac, Rappahannock, York and James--as well as a complex 
and dynamic patchwork of barrier islands, salt marshes, tidal flats and 
large coastal bays along the Delmarva Peninsula (TNC, 2002 in draft). 
Riverine spawning/nursery habitat for the two remaining Atlantic 
sturgeon groupings in the Southeast likewise occur in separate and 
distinct ecoregions. Therefore, the ecoregion delineations support that 
the physical and chemical properties of the Atlantic sturgeon spawning 
rivers are unique to each population grouping. The five discrete U.S. 
Atlantic sturgeon population segments are ``significant'' as defined in 
the DPS policy, given that the spawning rivers for each population 
segment occur in a unique ecological setting.
    Further, because each discrete population segment is genetically 
distinct and reproduces in a unique ecological setting, the loss of any 
one of the discrete population segments is likely to create a 
significant gap in the range of the taxon. Atlantic sturgeon that 
originate from other discrete population segments are not expected to 
re-colonize systems except perhaps over a long time frame (e.g., 
greater than 100 years), given that gene flow is low between the five 
discrete population segments (Secor and Waldman, 1999) and the 
geographic distances between spawning rivers of different population 
segments are relatively large (ASSRT, 2007). Therefore, the loss of any 
of the discrete population segments would result in a significant gap 
in the range of Atlantic sturgeon, and negatively impact the species as 
a whole, given the strong natal homing behavior of the species.
    In summary, the five Atlantic sturgeon discrete population segments 
meet the significance criterion of the DPS policy because they each 
persist in a unique ecological setting, and the loss of any of these 
discrete population segments would result in a significant gap in the 
range of the taxon. As described in the status review report, the SRT 
concluded that these five population segments of Atlantic sturgeon 
within the United States (identified above) should be considered 
significant under the DPS policy guidelines. We, therefore, concur with 
the SRT's conclusion that five Atlantic sturgeon DPSs occur within the 
United States. The five DPSs are hereafter referred to as: (1) GOM, (2) 
NYB, (3) CB, (4) Carolina, and (5) South Atlantic DPSs (Figure 2).

[[Page 61880]]

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Current Status of the GOM, NYB, and CB DPSs

    After completing the DPS analysis, we next considered the current 
status of the three DPSs that occur within the Northeast Region's 
jurisdiction, the GOM, NYB, and CB DPSs, as well as the factors 
affecting each of these Atlantic sturgeon DPSs in relation to the ESA's 
standards for listing (see Analysis of Factors, below). The ESA and its 
implementing regulations require listing determinations to be based on 
the current status of the species and the factors presently affecting 
the species or likely to affect the species in the future.
    Many of the activities causing harm to Atlantic sturgeon have 
occurred for years, even decades. Similarly, some conservation actions 
have been in place for years (e.g., prohibition on catch and retention 
of Atlantic sturgeon). The past impacts of human activity on the GOM, 
NYB, and CB DPSs cannot be particularized in their entirety.

[[Page 61881]]

However, to the extent they have manifested themselves at the 
population level, such past impacts are subsumed in the information 
presented on their current status, recognizing that the benefits to 
these Atlantic sturgeon DPSs as a result of conservation activities 
already implemented may not be evident in the status and trend of the 
DPS for years, given the relatively late age to maturity for Atlantic 
sturgeon and depending on the age class(es) affected.

Gulf of Mexico (GOM) DPS

    The GOM DPS includes all Atlantic sturgeon whose range occurs in 
watersheds from the Maine/Canadian border and extending southward to 
include all associated watersheds draining into the Gulf of Maine as 
far south as Chatham, MA, as well as wherever these fish occur in 
coastal bays, estuaries, and the marine environment from the Bay of 
Fundy, Canada, to the Saint Johns River, FL. Within this range, 
Atlantic sturgeon have been documented from the following rivers: 
Penobscot, Kennebec, Androscoggin, Sheepscot, Saco, Piscataqua, and 
Merrimack. The Kennebec River is currently the only known spawning 
river for the GOM DPS. Evidence of Atlantic sturgeon spawning in other 
rivers of the GOM DPS is not available. However, Atlantic sturgeon 
continue to use these historical spawning rivers and may represent 
additional spawning groups (ASSRT, 2007). The majority of historical 
Atlantic sturgeon spawning habitat is accessible in all but the 
Merrimack River of the GOM DPS. Therefore, the availability of spawning 
habitat does not appear to be the reason for the lack of observed 
spawning in other GOM DPS rivers. However, whether Atlantic sturgeon 
spawning habitat in the GOM DPS is fully functional is difficult to 
quantify.
    Known threats to Atlantic sturgeon of the GOM DPS include effects 
to riverine habitat (e.g., dredging, water quality) as well as threats 
that occur throughout their marine range (e.g., fisheries bycatch). 
There are no current abundance estimates for the GOM DPS of Atlantic 
sturgeon. The CPUE of subadult Atlantic sturgeon in a multi-filament 
gillnet survey conducted on the Kennebec River was considerably greater 
for the period of 1998-2000 (CPUE=7.43) compared to the CPUE for the 
period 1977-1981 (CPUE = 0.30). The CPUE of adult Atlantic sturgeon 
showed a slight increase over the same time period (1977-1981 CPUE = 
0.12 versus 1998-2000 CPUE = 0.21) (Squiers, 2004). There is also new 
evidence of Atlantic sturgeon presence in rivers (e.g., the Saco River) 
where they have not been observed for many years.

New York Bight (NYB) DPS

    The NYB DPS includes all Atlantic sturgeon whose range occurs in 
watersheds that drain into coastal waters, including Long Island Sound, 
the New York Bight, and Delaware Bay, from Chatham, MA to the Delaware-
Maryland border on Fenwick Island, as well as wherever these fish occur 
in coastal bays, estuaries, and the marine environment from the Bay of 
Fundy, Canada, to the Saint Johns River, FL. Within this range, 
Atlantic sturgeon have been documented from the Hudson and Delaware 
rivers as well as at the mouth of the Connecticut and Taunton rivers, 
and throughout Long Island Sound. There is evidence to support that 
spawning occurs in the Hudson and Delaware Rivers. Evidence of Atlantic 
sturgeon spawning in the Connecticut and Taunton Rivers is not 
available. However, Atlantic sturgeon continue to use these historical 
spawning rivers (ASSRT, 2007). The majority of historical spawning 
habitat is accessible to the NYB DPS. Therefore, the availability of 
spawning habitat does not appear to be the reason for lack of observed 
spawning in the Connecticut and Taunton Rivers. However, whether 
Atlantic sturgeon spawning habitat in these rivers is fully functional 
is difficult to quantify.
    Known threats to Atlantic sturgeon of the NYB DPS include effects 
to riverine habitat (e.g., dredging, water quality, and vessel strikes) 
as well as threats that occur throughout their marine range (e.g., 
fisheries bycatch). The only abundance estimate for Atlantic sturgeon 
belonging to the NYB DPS is 870 spawning adults per year for the Hudson 
River subpopulation, based on data collected from 1985-1995 (Kahnle et 
al., 2007). The accuracy of the estimate may be affected by bias in the 
reported harvest or estimated exploitation rate for that time period 
(Kahnle et al., 2007). Underreporting of harvest would have led to 
underestimates of stock size, while underestimates of exploitation 
rates would have resulted in overestimates of stock size (Kahnle et 
al., 2007). In addition, the current number of spawning adults may be 
higher given that the estimate is based on the time period prior to the 
moratorium on fishing for and retention of Atlantic sturgeon.
    There is no abundance estimate for the Delaware River 
subpopulation. Delaware's Department of Natural Resources and 
Environmental Control (DNREC) has been conducting surveys for Atlantic 
sturgeon since 1991 (DNREC, 2009). Atlantic sturgeon are a Delaware 
endangered species (state-listed).

CB DPS

    The CB DPS includes all Atlantic sturgeon whose range occurs in 
watersheds that drain into the Chesapeake Bay and into coastal waters 
from the Delaware-Maryland border on Fenwick Island to Cape Henry, VA, 
as well as wherever these fish occur in coastal bays, estuaries, and 
the marine environment from the Bay of Fundy, Canada, to the Saint 
Johns River, FL. Within this range, Atlantic sturgeon have been 
documented from the James, York, Potomac, Rappahannock, Pocomoke, 
Choptank, Little Choptank, Patapsco, Nanticoke, Honga, and South rivers 
as well as the Susquehanna Flats. Historical evidence suggests that 
several of these, including the James, York, Potomac, Susquehanna, and 
Rappahannock Rivers, were Atlantic sturgeon spawning rivers. However, 
the James River is currently the only known spawning river for the CB 
DPS. Evidence of Atlantic sturgeon spawning in other rivers of the CB 
DPS is not available, although spawning is suspected to occur in the 
York based on genetics data and anecdotal reports. The majority of 
historical Atlantic sturgeon spawning habitat is accessible, but it is 
unknown whether it is fully functional.
    Known threats to Atlantic sturgeon of the CB DPS include effects to 
riverine habitat (e.g., dredging, water quality, vessel strikes) as 
well as threats that occur throughout their marine range (e.g., 
fisheries bycatch). There are no current abundance estimates for the CB 
DPS. The Maryland Reward Program has resulted in the documentation of 
over 1,133 wild Atlantic sturgeon since 1996. The Virginia Atlantic 
sturgeon reward program in the Chesapeake Bay documented and measured 
295 Atlantic sturgeon in 1997 and 1998 (Spells, 2007). However, since 
sturgeon from multiple DPSs occur in the Chesapeake Bay, it is unlikely 
that all of the sturgeon captured in either reward program originated 
from the CB DPS.

Analysis of Factors Affecting the Three Northeast Region DPSs of 
Atlantic Sturgeon

    A species shall be listed if the Secretary of Commerce determines, 
on the basis of the best scientific and commercial data available after 
conducting a review of the species' status, that the species is in 
danger of extinction throughout all or a significant portion of its 
range (i.e., ``endangered'')

[[Page 61882]]

or is likely to become an endangered species within the foreseeable 
future throughout all or a significant portion of its range (i.e., 
``threatened'') because of any one or a combination of the following 
factors: (1) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (2) over utilization for 
commercial, recreational, scientific, or educational purposes; (3) 
disease or predation; (4) the inadequacy of existing regulatory 
mechanisms; or (5) other natural or manmade factors affecting its 
continued existence.
    The SRT took a multi-step approach for each DPS to answer whether 
there were: (1) Sufficient data to conclude whether a DPS is threatened 
or endangered; (2) sufficient data to conclude that a DPS was not 
threatened or endangered; or (3) insufficient data to allow a full 
assessment of the populations within a DPS. The SRT identified the 
threats specific to Atlantic sturgeon and then used a semi-quantitative 
approach to assess the overall effect of those threats to each DPS 
(ASSRT, 2007; Patrick and Damon-Randall, 2008).
    The ESA does not define what timeframe corresponds with the phrase 
``within the foreseeable future'' in its definition of the term 
``threatened.'' Therefore, before beginning the analysis of the Section 
4(a)(1) factors, it was necessary for the SRT to define the timeframe 
(Patrick and Damon-Randall, 2008). Following the example of a past 
status review team (Acropora Biological Review Team, 2005), the 
Atlantic sturgeon SRT determined that the appropriate period of time 
would: (1) Depend on the particular kinds of threats; (2) consider the 
life history characteristics of the species; (3) consider specific 
habitat requirements for the species; and (4) allow for the 
conservation and recovery of the species and the ecosystems upon which 
it depends (ASSRT, 2007; Patrick and Damon-Randall, 2008). Based on 
these, the SRT agreed that 20 years would be the appropriate timeframe 
for defining ``the foreseeable future'' for Atlantic sturgeon (ASSRT, 
2007; Patrick and Damon-Randall, 2008). The SRT also concluded that 20 
years is an appropriate timeframe for determining the status of a 
species, as it was not too far into the future that qualitative 
analysis would prove to be ineffective or unreliable, it allowed 
sufficient time (10+ years) to determine the productivity of Atlantic 
sturgeon subpopulations using standardized protocols (Sweka et al., 
2006), and it is the approximate age of maturity for Atlantic sturgeon 
or is approximately equal to one generation (Scott and Crossman, 1973; 
Smith et al., 1982; Young et al., 1998).

The Present or Threatened Destruction, Modification, or Curtailment of 
the Species' Habitat or Range

    The SRT identified barriers (i.e., dams, tidal turbines), dredging, 
and water quality (e.g., dissolved oxygen levels, water temperature, 
and contaminants) as threats that affect Atlantic sturgeon habitat or 
range. The SRT did not specifically consider global climate change. 
Since completion of the SRT report, additional information has become 
available on the effects of global climate change in the Northeast and 
Mid-Atlantic where habitat for the GOM, NYB, and CB DPSs occurs.
    As noted in the status review report, dams for hydropower 
generation, flood control, and navigation have the potential to affect 
Atlantic sturgeon by impeding access to spawning and foraging habitat, 
modifying free-flowing rivers to reservoirs, and altering downstream 
flows and temperatures. Turbines for power generation could, similarly, 
impede access to spawning and foraging habitat but are also known to 
injure and kill sturgeon as a result of direct contact with the turbine 
blades. Environmental impacts of dredging include direct removal or 
burial of organisms, elevated turbidity or siltation, contaminant 
resuspension, noise or disturbance, alterations to hydrodynamic regime 
and physical habitat, and loss of riparian habitat (Chytalo, 1996; 
Winger et al., 2000). Water quality can be affected by many activities 
such as industrial activities, forestry, agriculture, land development 
and urbanization that can result in discharges of pollutants, changes 
in water temperature and dissolved oxygen levels, alteration of water 
flow, and the addition of nutrients or sediment from erosion. Any of 
these can affect sturgeon at various life stages depending on the 
extent of the threat and the life stage affected. There is a large and 
growing body of literature on past, present, and future impacts of 
global climate change induced by human activities--commonly referred to 
as ``global warming.'' Some of the likely effects commonly mentioned 
are sea level rise, increased frequency of severe weather events, and 
change in air and water temperatures.

Dams

    The SRT used GIS tools and dam location data collected by Oakley 
(2005) to determine the number of miles of available habitat in rivers 
where Atlantic sturgeon historically spawned. As previously described, 
within the GOM DPS, Atlantic sturgeon are known to spawn in the 
Kennebec River. The Penobscot, Sheepscot, Androscoggin, and Merrimack 
Rivers are known to have supported spawning in the past (ASSRT, 2007). 
Atlantic sturgeon occur in the Saco and Piscataqua Rivers, although 
there is no information on historical or current spawning activity for 
Atlantic sturgeon in these rivers (ASSRT, 2007; J. Sulikowski, UNE, 
pers. comm., 2009).
    Historically, the upstream migration of Atlantic sturgeon in the 
Kennebec River was limited to Waterville, ME, which is the location of 
Ticonic Falls (river kilometer (rkm) 98) (NMFS and USFWS, 1998). The 
construction of Edwards Dam in 1837, downstream of the Ticonic Falls, 
denied Atlantic sturgeon access to historical habitat in the Kennebec 
River until 1999 when the dam was removed. Since its removal, access to 
100 percent of historical habitat has been restored. In the 
Androscoggin River, the Brunswick Hydroelectric Dam is located at the 
head-of-tide near the site of the natural falls. The location of 
historical spawning grounds on the Androscoggin is unknown, but it is 
unlikely that Atlantic sturgeon could navigate the natural falls 
located at Brunswick Dam (NMFS and USFWS, 1998). Therefore, the dam is 
unlikely to have limited access of Atlantic sturgeon to their spawning 
habitat. Similarly, Atlantic sturgeon upstream migration within the 
Sheepscot River is thought to have been historically limited to the 
lower river (rkm 32) just below the first dam on the river (rkm 35); 
therefore, 100 percent of the historical habitat (based on river 
kilometers) is available to Atlantic sturgeon in the Sheepscot.
    In contrast to the aforementioned rivers, access to Atlantic 
sturgeon spawning habitat is impeded on the Penobscot River. 
Historically, the falls at Milford, rkm 71, were likely the first 
natural obstacle to Atlantic sturgeon migration on the Penobscot River 
(L. Flagg, MEDMR, pers. comm., 1998). In 1833, the Veazie Dam was 
constructed on the Penobscot River at rkm 56, blocking 21 percent of 
Atlantic sturgeon habitat. In 1875, the Treats Falls Bangor Dam was 
built five kilometers downstream of the Veazie, which also impeded 
migration upstream (ASSRT, 2007). However, this dam was breached in 
1977 (ASSRT, 2007). Therefore, 79 percent of Atlantic sturgeon habitat 
is currently accessible on the Penobscot (ASSRT, 2007). In 2008, the 
Penobscot River Restoration Trust, a non-profit corporation, exercised 
its option to purchase the Veazie and two other dams

[[Page 61883]]

on the Penobscot (ASSRT, 2007). In doing so, the Trust has the right 
to, in part, decommission or remove the Veazie Dam, thus reopening 
miles of habitat for Atlantic sturgeon and other diadromous species 
(ASSRT, 2007). However, funds for the removal need to be generated and 
permits need to be secured, and it remains uncertain whether all of the 
goals will be achieved. If Atlantic sturgeon were able to ascend the 
falls at Milford, they could have migrated without obstruction to 
Mattaseunk (rkm 171) (ASSRT, 2007). However, evidence is lacking to say 
with certainty that Atlantic sturgeon were able to ascend the falls at 
Milford.
    Information on Atlantic sturgeon use of the Saco River in Maine 
became available after completion of the status review report. The last 
focused study of the Saco River was almost 30 years ago, and continued 
use of the river by Atlantic sturgeon was uncertain at the time of the 
status review report. However, Atlantic sturgeon have been captured 
during routine trawl sampling in the river during 2008 and 2009 as part 
of a 2-year monitoring project of the Saco River/Estuary. Tagging and 
tracking of the captured fish has shown that Atlantic sturgeon are 
making use of the river up to the Cataract Dam (J. Sulikowski, UNE, 
pers. comm., 2009), the first dam on the river at approximately rkm 6 
(Atlantic Salmon Commission, 1983). There are several dams on the Saco 
River known to have blocked fish passage for species such as Atlantic 
salmon, shad, and alewives (MEDMR, 1994). The effect of such dams on 
the Atlantic sturgeon that currently use the river is unknown. 
Likewise, there are several dams on the Piscataqua River, and the 
effect of such dams on the Atlantic sturgeon that currently use the 
river is unknown.
    Within the GOM DPS, access to historical spawning habitat is most 
severely impacted in the Merrimack River (ASSRT, 2007). Hoover (1938) 
identified Amoskeag Falls (rkm 116) as the historical limit for 
Atlantic sturgeon in the Merrimack River. In the 1800s, construction of 
the Essex Dam in Lawrence, MA (rkm 49) blocked the migration of 
Atlantic sturgeon to 58 percent of its historically available habitat 
(Oakley, 2003; ASSRT, 2007). Tidal influence extends to rkm 35; 
however, in the summer months when river discharge is lowest, the salt 
wedge extends upriver, resulting in approximately 19 km of tidal 
freshwater and 9 km of freshwater habitat (Keiffer and Kynard, 1993). 
Based on a detailed description by Keiffer and Kynard (1993), the 
accessible portions of the Merrimack seem to be suitable for Atlantic 
sturgeon spawning and nursery habitat. Nevertheless, the presence of 
the dam means that only 42 percent of historical Atlantic sturgeon 
habitat is currently available (ASSRT, 2007).
    Within the NYB DPS, there is evidence of Atlantic sturgeon spawning 
in the Hudson and Delaware Rivers (ASSRT, 2007). Historical records 
indicate that Atlantic sturgeon spawned in the Taunton River at least 
until the turn of the century (ASSRT, 2007), and also occurred in the 
Connecticut River (Judd, 1905; Murawski and Pacheco, 1977; Secor, 2002; 
ASSRT, 2007). By 1898, the overall New England harvest of Atlantic 
sturgeon was quite low, 36 mt, and only occurred in Maine, 
Massachusetts, and Connecticut (Secor, 2002). There is no recent 
evidence (within the last 15 years) to confirm that spawning currently 
occurs in either the Taunton or Connecticut Rivers (ASSRT, 2007). 
Atlantic sturgeon are present in both rivers, and likely represent 
sturgeon originating from other spawning rivers along the coast.
    In general, Atlantic sturgeon access to historical or spawning 
habitat believed to be historical is relatively unimpeded on all four 
of these NYB DPS rivers. The first impediment to migrating Atlantic 
sturgeon on the Hudson River is the Federal Dam located at Troy, NY 
(ASSRT, 2007). This dam location is upstream of Catskill (rkm 204), 
which is the northern extent of Atlantic sturgeon spawning and nursery 
habitat (Kahnle et al., 1998). Therefore, 100 percent of Atlantic 
sturgeon habitat is still available on the Hudson (ASSRT, 2007). 
Similarly, 100 percent of Atlantic sturgeon habitat is believed to be 
accessible on the Delaware River where 140 rkm of Atlantic sturgeon 
habitat are available extending from Delaware Bay to the fall line at 
Trenton, NJ with no dams present (ASSRT, 2007). Historical upstream 
migration of Atlantic sturgeon in the Taunton River is unknown. 
However, Atlantic sturgeon have access to 89 percent of the river 
downstream of the Town River Pond Dam (ASSRT, 2007). Similarly, it is 
not clear how far up the Connecticut River Atlantic sturgeon 
historically migrated. In all but low flow years, it is likely that 
Atlantic sturgeon could pass the Enfield Rapids prior to dam 
construction (Enfield Dam), which occurred in three stages between 1829 
and 1881 (Judd, 1905). The falls at South Hadley, MA, which is now the 
site of the Holyoke Dam, are considered the upstream limit of sturgeon 
in this system; however, there is one historical record of an Atlantic 
sturgeon sighted as far upstream as Hadley, MA (24 rkm upstream from 
South Hadley) (ASSRT, 2007). Als