[Federal Register Volume 72, Number 124 (Thursday, June 28, 2007)]
[Proposed Rules]
[Pages 35388-35393]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-12564]



National Oceanic and Atmospheric Administration

50 CFR Parts 223 and 224

[Docket No. 070613193-7194-01; I.D. 121903C]

Endangered and Threatened Wildlife and Plants; Finding on Whether 
to List Eastern Oyster as a Threatened or Endangered Species

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

[[Page 35389]]

ACTION: Notice of a listing determination and availability of a status 
review document.


SUMMARY: The eastern oyster biological review team (BRT) has prepared 
an Endangered Species Act (ESA) status review report for the eastern 
oyster (Crassostrea virginica) and submitted it to NMFS. After 
reviewing the best available scientific and commercial information, we 
(NMFS) have determined that listing the eastern oyster as threatened or 
endangered under the ESA is not warranted at this time.

DATES: This finding is effective on June 28, 2007.

ADDRESSES: The eastern oyster status review report and list of 
references are available by submitting a request to the Assistant 
Regional Administrator, Protected Resources Division, Northeast Region, 
NMFS, One Blackburn Drive, Gloucester, MA 01930. The status review 
report and other reference materials regarding this determination can 
also be obtained via the Internet at: http://www.nero.noaa.gov/prot_res/CandidateSpeciesProgram/index.html.

Region (978) 281-9300 x6535 or Marta Nammack, NMFS, Office of Protected 
Resources (301) 713-1401.



    On January 11, 2005, we received a petition from Mr. Wolf-Dieter 
Busch (the petitioner), Ecosystem Initiatives Advisory Services, to 
list eastern oyster (Crassostrea virginica) as threatened or endangered 
under the ESA. After reviewing the information contained in the 
petition and that which was readily available to us, we determined that 
there was sufficient information to indicate that the petitioned action 
may be warranted. On May 18, 2005, we published a positive 90-day 
finding in the Federal Register, which initiated the status review 
    On October 19, 2005, we received a letter from the petitioner dated 
October 13, 2005, requesting the recall of the eastern oyster petition. 
In his letter, the petitioner indicated that his request to withdraw 
the petition was due to the public and industry's confusion over the 
petition and listing process. He noted the significant concerns of some 
that the species may be listed as endangered and thereby, create severe 
restrictions and regulations for this resource. He also expressed 
concern that, given the timeline of the review, NMFS may not have 
enough information to determine if eastern oyster subspecies exist. He 
concluded that he hoped that we would continue with the review as he 
considers the status review report to be a comprehensive resource which 
will be of great value in focusing restoration activities for this 
    We accepted this request and as a result, ceased the evaluation of 
the petition. However, a considerable amount of effort had been 
expended by the BRT at the point at which the withdrawal of the 
petition occurred. Also, the completed status review report is the most 
timely and comprehensive resource document for this species. As such, 
we determined that because the report is a useful tool in guiding 
future management decisions, the BRT would complete its report. We also 
decided to complete our evaluation of the status of the species under 
the ESA as stated in the Federal Register notice announcing the 90-day 
finding on the petition (70 FR 28510).
    As part of the full evaluation of the status of the species under 
the ESA, we requested that the Center for Independent Experts provide 
three independent consultants to serve as peer reviewers. These 
reviewers were tasked with reading and reviewing the status review 
report and providing a written summary of their comments. Specifically, 
they were asked to address the following (at a minimum): (1) Are 
species and/or subspecies delineations supported by the information 
presented?; (2) Does the report include and cite the best scientific 
and commercial information available on the species and threats to it 
and its habitat?; (3) Are the scientific conclusions sound and derived 
logically from the results?; (4) Where available, are opposing 
scientific studies or theories acknowledged and discussed? The peer 
reviewers completed their task in October 2006 and specifically found 
that the status review report contained the best scientific and 
commercial information available.

Biology and Life History of the Eastern Oyster

    The eastern oyster occurs naturally in a great diversity of 
habitats along the western Atlantic Ocean from the Canadian Maritime 
Provinces to the Gulf of Mexico, Panama, and the Caribbean Islands 
(Carlton and Mann, 1996; Abbott, 1974; MacKenzie, 1997a; Jenkins et 
al., 1997; FAO, 1978). The eastern oyster has been transplanted outside 
of its natural range and now may be found in western Canada, western 
United States, western Mexico, Hawaii, Fiji, Tonga, Japan, Mauritius-
Indian Ocean, and possibly England (Ruesink et al., 2005).
    The eastern oyster is protandric, as individuals first mature as 
males then typically change to female later in life, and there is also 
evidence suggesting that the process is reversible later in life 
(Thompson et al., 1996). Oysters may change sex in response to 
environmental, nutritional, and/or physiological stresses, or sex 
determination may be influenced by the sex and proximity of nearby 
oysters (Tranter, 1958, cited by Thompson et al., 1996; Bahr and 
Hillman, 1967; Davis and Hillman, 1971; Ford et al., 1990; Needler, 
1932; Burkenroad, 1931; Smith, 1949; and Menzel, 1951, all cited by 
Thompson et al., 1996). Estimates of fecundity range from 2 to 115 
million eggs per female, depending on size and geographic location 
(Galtsoff, 1930, 1964; Davis and Chanley, 1956; Cox, 1988; Cox and 
Mann, 1992; all cited in Thompson et al., 1996).
    Spawning is initiated by a combination of factors including water 
temperature, salinity, and physiochemical interactions (Galtsoff, 1964; 
and Loosanoff, 1953, cited by Berrigan et al., 1991; Hayes and Menzel, 
1981; Hofstetter, 1977, 1983). Spawning is seasonal (summer) throughout 
the mid- to northern Atlantic portions of the species' range. In 
southern waters, spawning occurs in all but the coldest months 
(Berrigan et al., 1991). Conditions generally required for spawning 
include water temperatures at or above 20 C and salinity higher than 10 
parts per thousand (ppt).
    After fertilization, oysters develop through several free-swimming 
larval stages before attaching to a hard substrate and becoming 
sessile. The mechanisms for larval dispersal and recruitment are still 
unclear (Epifanio, 1988). Larval dispersal is generally explained by 
``passive'' transport induced by physical factors, by an ``active'' 
process involving larval swimming, or by a combination of both 
(Deskshenieks et al., 1996). The first larval stage (trochophore) is 
formed 4 to 6 hours following fertilization and lasts approximately 1 
to 2 days. The trochophore larva does not feed, but subsequent larval 
stages (veliger) are planktotrophic, feeding on small plants and 
animals (Kennedy, 1996). Veliger stages, lasting up to 2 months 
(Hopkins, 1931), include several morphological changes to the larvae 
resulting in fully developed larvae possessing a well-developed foot.
    As oyster larvae become competent to settle they must locate a 
suitable substrate upon which to attach. Larvae may exhibit exploratory 
behavior in

[[Page 35390]]

locating a suitable substrate upon which to settle (Burke, 1983, as 
cited in Kennedy, 1996). Both environmental and internal cues are used 
in determining when and where veliger larvae will settle (Kennedy, 
1996). Settlement is a behavioral response that can be repeated or 
reversed and is followed by metamorphosis, which results in 
morphological changes and is permanent (Kennedy, 1996). There is 
evidence that suggests metamorphosis is triggered by salinity and by 
chemicals given off by live oysters and bio-films on other suitable 
substrates (Hidu and Haskin, 1971; Keck et al., 1971; Kennedy, 1996).
    Temperature, salinity, and food availability greatly influence 
oyster growth, and, therefore, growth rates vary seasonally, with 
maximum growth occurring during the summer and fall. Eastern oysters 
have been reported to survive freezing temperatures in shallow-water 
habitats and after being exposed to temperatures in excess of 45[deg] C 
in intertidal areas (Galtsoff, 1964; Shumway, 1996). However, exposures 
to temperatures above approximately 35[deg] C will adversely affect 
pumping rate and thereby, feeding (Loosanoff, 1958; and Galtsoff, 1928, 
as cited by Shumway, 1996). Oysters can tolerate salinities from 0 to 
42 ppt, although growth rates are affected by lower salinities (Quast 
et al., 1988; Shumway, 1996).
    Oysters are filter feeders, feeding primarily on phytoplankton and 
suspended detritus (Langdon and Newell, 1996). Crassostrea virginica 
are capable of adjusting feeding rates depending on the size, type, and 
composition of the available food source (Baldwin, 1995; Baldwin and 
Newell, 1995a, 1995b, as cited in Kennedy, 1996).
    The eastern oyster plays an important ecological role in the 
environment in which it inhabits. Self sustaining oyster populations 
form reefs that: (1) contribute to trophic dynamics by promoting 
species diversity; (2) provide structural integrity that supports 
community stability, enhances habitat values, and affects water 
circulation and flow patterns; and (3) perform ecological services 
which improve water quality and recycle nutrients.


    Abundance of the eastern oyster is known to have varied or declined 
in many estuaries in which it was previously known to be abundant. In 
some estuaries, abundance has declined due to one or more of the 
stressors discussed below. Some populations have declined dramatically 
(e.g., the Hudson-Raritan Estuary). However, even in these locations, 
with effort, oysters can be found. The eastern oyster can be found as 
isolated individuals or clusters even in unlikely urbanized places, 
such as the Hackensack River, Arthur Kill, Harlem River, East River and 
the Bronx River (Steimle, 2005). However, these isolated survivors may 
currently exist at the thinnest of margins even though habitat quality 
has measurably improved and is currently suitable for good growth, as 
evidenced by oyster culturist results in this estuary complex.
    The persistence of oysters in isolated areas at low abundance for 
perhaps decades, is not uncommon. Some local populations are now too 
widely dispersed to support enough successful spawning-fertilization 
and recruitment for natural repopulation (Pers. Comm. Luckenbach, 
2005). The low abundance situation of the Hudson-Raritan area may exist 
in other urbanized estuaries where oyster population surveys have not 
been done for decades. Some shellfish surveys were conducted without 
proper oyster sampling gear and focus because the oyster was not 
considered part of a useful or manageable fishery resource any more. 
Also, local management agencies may not want to publicize the existence 
of oysters in some areas to avoid potential public health consequences 
because of bacterially contaminated water.
    According to the BRT, the notable decline of the oyster abundance 
distributions from estimated historic abundance distribution levels 
seems to be most prevalent in the more urbanized northeast, e.g., 
Chesapeake Bay, the Hudson-Raritan Estuary, southern Long Island NY, 
and some New England estuaries. However, most of the data to document 
this decline comes from fishery-dependent sources, which is somewhat 
controlled by socio-economic, not ecological, factors (MacKenzie, 
1996). This information base may not present an accurate picture of the 
abundance and status of oyster populations in many areas. Based upon 
numerous southern Atlantic/Gulf Coast state reports, the oyster 
distribution abundances south of Chesapeake Bay seem relatively stable, 
despite occasional major disturbances, such as hurricanes (Marsh, 2004; 
Perret, 2005).

Consideration as a ``Species'' Under the ESA

    Under the ESA, the term ``species'' refers to ``a species, 
subspecies of fish or wildlife or plants, and any distinct population 
segment of any species of vertebrate fish or wildlife which interbreeds 
when mature.'' Distinct population segments of the eastern oyster 
cannot be listed under the ESA because it is an invertebrate. The term 
``subspecies,'' while identified as a term in the ESA's definition of 
``species,'' is not itself defined in the ESA. As a matter of science, 
however, subspecies delineations may rely on discernable morphological, 
behavioral, genetic, or physiological differences.
    Due to extreme morphological plasticity, C. virginica has not yet 
been examined with the goal of identifying morphological differences 
between populations. However, in 1951, Loosanoff and Nomejko recognized 
the existence of physiological races along the latitudinal range of C. 
virginica. Since that time, most physiological differences have been 
found to be related to differences in environmental conditions. Whether 
additional physiological or morphological studies would be informative 
is questionable, as any differences between Gulf and Atlantic 
populations are more likely to be due to local environmental conditions 
rather than genetic differences (Gaffney, 1996).
    Populations of C. virginica were initially found to be homogenous 
in allozyme frequencies across a large portion of the species range. An 
early allozyme study by Buroker (1983) provided evidence of a uniform 
population from Cape Cod to Corpus Christi using 32 allozyme loci which 
exhibited estimated genetic similarities among populations of 99 
percent. Several recent genetic studies have been undertaken to better 
understand the population structure of C. virginica, and these studies 
have found strong patterns of differentiation on the basis of different 
sequencing data. Studies indicate two separate populations, one within 
the Atlantic region and one within the Gulf of Mexico, with an 
intermediate zone between these populations found on the eastern coast 
of Florida in the general area of Cape Canaveral. Crassostrea virginica 
is not the only western Atlantic species with a notable genetic 
transition from the temperate Atlantic to subtropical Gulf regions. 
Similar genetic patterns of population subdivision between Atlantic and 
Gulf populations can be found in a wide variety of coastal and marine 
species (Avise, 1992; 2000). Also, a genetically distinct population of 
C. virginica was found in the Laguna Madre area of Texas by different 
studies that have included samples from this general area (Groue and 
Lester, 1982; Buroker, 1983; Hedgecock and Okazaki, 1984; King et al., 
1994). Genetic differentiation of the Laguna Madre

[[Page 35391]]

eastern oyster population may be due to adaptation to hypersaline 
conditions (up to 35 ppt) created by low levels of precipitation and 
lack of river inflow, as well as selection or genetic drift due to 
isolation from oyster populations further north (King et al., 1994).
    Although the aforementioned studies indicate Atlantic/Gulf 
population structure, other studies have agreed with Buroker's 
conclusion of a panmictic population. MacDonald et al. (1996) found a 
lack of genetic structure among six anonymous nuclear DNA loci from 
oysters in Panacea, FL, and Charleston, SC. In 1998, Hare and Avise 
(1992) looked at oysters from Massachusetts to Louisiana and found no 
population structure at three nuclear loci.
    Each peer reviewer was individually asked whether species/
subspecies delineations existed for the eastern oyster as a matter of 
scientific fact. Two of the three felt that the existing information 
was not sufficient to definitively establish eastern oyster subspecies. 
The remaining reviewer felt that the available genetic information 
indicates that the Gulf and Atlantic populations of eastern oyster are 
``at a stage of incipient speciation and should probably be considered 
subspecies.'' The peer reviewers and the members of the BRT all agree 
that it is difficult to define and delineate subspecies under normal 
scientific definitions of the terms.
    In summation, subspecies delineations often rely on discernable 
morphological, behavioral, or physiological differences. However, these 
differences are not readily apparent in an invertebrate species such as 
the eastern oyster. Thus, a subspecies delineation for the eastern 
oyster would have to rely predominantly on the available genetic data, 
which have provided mixed results. Because the data needed to support a 
subspecies delineation are inconclusive, we examined the listing 
potential for the eastern oyster both as a separate subspecies and as a 
single biological unit. Ultimately, we determined that in either case, 
the species/subspecies determination would not impact or alter the 
final listing determination. Accordingly, we note the genetic 
differences but do not make a subspecies delineation based on the 
present facts.

Species/Subspecies Status

    The process for determining whether a species (as defined above) 
should be listed is based upon the best available scientific and 
commercial information. We must list a species if it is endangered or 
threatened because of any of the following ESA section 4(a)(1) factors: 
(a) The present or threatened destruction, modification, or curtailment 
of its habitat or range; (b) overutilization for commercial, 
recreational, scientific, or educational purposes; (c) disease or 
predation; (d) inadequacy of existing regulatory mechanisms; and (e) 
other natural or manmade factors affecting the continued existence of 
the species. These factors are considered in the following sections.

The Present or Threatened Destruction, Modification, or Curtailment of 
its Habitat or Range

    There are few data available regarding historic and current oyster 
reef acreage estimates, and available fisheries dependent and 
independent data are limited. In order to gather additional data to 
assess the status of the species, the BRT conducted a telephone survey 
of state resource managers and oyster experts. Respondents were asked 
to provide the following information for each estuary within their 
region/area: historic and current oyster acreage estimates; harvest 
rates and regulations; the sustainability of oyster populations with 
and without restoration; recruitment; and the primary stressors facing 
oyster populations. The survey indicated that the eastern oyster is 
widely distributed throughout its range and is currently present in all 
but one of the 71 estuaries represented. This wide distribution is 
beneficial in many ways in that it provides evidence of the species' 
resiliency and adaptability and makes the species less susceptible to 
extinction from a localized catastrophic event (e.g., a hurricane or 
oil spill). We, therefore, concluded that the one estuary without 
oysters, the upper Laguna Madre region, does not represent a large 
portion of the vast geographic range of the species/subspecies and is 
considered minor in terms of the biological significance to the species 
or hypothetical subspecies.
    The BRT reported that the eastern oyster displays a wide range of 
survival strategies as it is both a colonizer and an ecosystem engineer 
and has high reproductive potential. The species' ability to adapt to a 
wide range of environmental conditions (e.g., tolerance for low 
dissolved oxygen and wide ranges in salinity and temperature) makes it 
resilient. The eastern oyster inhabits a naturally-variable 
environment, and evidence suggests that past local extirpations and 
colonizations have been common over geological time. Crassostrea 
virginica is broadly distributed in the western North Atlantic, and its 
distribution has not changed as threats have increased over time. This 
is significant because range contraction is often used as an indicator 
of a problem in many widely distributed marine species. While 
separating the species into the two potential subspecies reduces the 
range of each of the subspecies (as compared to the full species), 
Atlantic and Gulf Coast oyster populations are still widespread, 
occupying areas from Maine to eastern Florida and western Florida to 
Texas, respectively. Based on the available data, we concluded that 
oyster abundance throughout these areas is sufficient to sustain these 
populations and prevent extinction. While the survey indicated some 
habitat within the range of the eastern oyster has been degraded or 
lost, we were able to conclude based upon the available information, 
including the survey, that the species' ability to adapt to various 
environmental conditions and its vast geographic range results in 
habitat degradation being a minimal threat that will not affect the 
species/subspecies' continued existence.

Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Information from the survey indicated that oyster harvests are at 
or near recent record low levels along the majority of the U.S. 
Atlantic coast; however, responding resource managers and independent 
experts considered overutilization (overharvesting) to currently be a 
minor threat to oyster populations. According to the BRT, areas along 
the Atlantic coast south of Cape Lookout and through the Gulf of Mexico 
appear to have avoided some of the extremely heavy historic utilization 
experienced by the area from Pamlico Sound to Long Island Sound. 
Harvest parameters in the Gulf of Mexico are currently less restrictive 
than those in the mid-Atlantic area, but oyster populations there 
appear to be effectively managed and monitored so that harvest impacts 
are not substantial (Marsh, 2004). Eastern oyster resources from 
Pamlico Sound to Long Island Sound appear to have suffered from long-
term overutilization. State managers in this region have attempted to 
protect public oyster stocks by conducting stock assessments, setting 
conservative harvest quotas, lowering daily catch limits, limiting 
harmful gear use, and reducing harvest seasons. Attempts to restore 
oyster populations and rebuild the resource through general cultch 
planting, reef rebuilding, and oyster sanctuaries/reserves are also 
becoming common management tools in

[[Page 35392]]

this region. In the survey, overharvesting is listed as occurring only 
in seven estuaries out of the 71 estuaries assessed. These seven 
estuaries represent a limited portion of the large geographic range of 
the species/subspecies, and overutilization in these areas represents a 
localized issue. Recreational harvest and harvest for scientific 
purposes were not identified as significant stressors to the eastern 
oyster. Long-term overutilization in many areas of the eastern oyster's 
range was a significant contributing factor to the species' historical 
decline. However, survey respondents no longer consider this to be a 
significant threat to the eastern oyster in the majority of the 
species/subspecies' range. Thus, we conclude that overutilization is 
not a significant ongoing threat that affects the continued existence 
of the eastern oyster species/subspecies.

Disease or Predation

    There are several predators on various life stages of the eastern 
oyster, including boring sponges and clams, mud worms, carnivorous 
gastropods, ctenophores, and a number of fish species. However, most of 
these predators exist as natural associations in the oyster reef 
community and, in general, most oysters in the population survive. 
Thus, these associations do not seem to be having an effect at the 
population level. The eastern oyster is affected primarily by two 
diseases - DERMO (a parasitic disease caused by the protozoan Perkinsus 
marinus) (Levine, 1978 = Dermocystidium marinum; Mackin et al., 1950 = 
Layirinthomyxa marina; Quick and Mackin, 1971) and MSX (another 
parasitic disease caused by the protozoan Haplosporidium 
nelsoni)(Haskin et al., 1966). The BRT reported that both of these 
diseases are capable of causing significant oyster mortalities. 
However, oysters infected by DERMO have the opportunity to spawn the 
first summer, and others may be able to spawn a second or third time 
before succumbing to an infection. With MSX, the salinity must be above 
15 ppt to sustain an infection. Thus, infections during drought years 
are more prevalent. As drought conditions wane, survivors and their 
progeny may reproduce to re-establish oyster populations. During the 
wetter years that occurred during the 1970s, there was significant 
recovery of oyster populations that had been devastated during the 
1950-1960 MSX epizootic in both Delaware and Chesapeake Bays. Oyster 
recovery management programs have concentrated on moderate to lower 
salinity areas that are less likely to support the development of 
oyster diseases. Research has been ongoing for several years to develop 
oysters that are disease tolerant. Also, resource managers help to 
control the spread of DERMO by controlling/preventing the 
transplantation of infected oysters to areas not currently infected by 
the disease. Based on the available information, we conclude that while 
both predation and disease may have effects on localized populations, 
impacts to the entire species/subspecies vary both spatially and 
temporally, allowing some affected populations to recover and sustain 
the species/subspecies. Thus, we conclude that neither disease nor 
predation are significant threats that affect the continued existence 
of the eastern oyster species/subspecies.

Inadequacy of Existing Regulatory Mechanisms

    The BRT indicated that regulatory mechanisms for eastern oyster are 
most logically defined as habitat resource protection (preventative 
measures), fishery-specific, and conservation/replenishment based. The 
eastern oyster is not a federally managed species. As such, each state 
is responsible for controlling harvest, protecting habitat, and 
conserving or replenishing oyster populations. This results in many 
different types of regulations to protect oysters throughout their 
    Habitat measures are those defined at the Federal, state, or local 
level designed to protect aquatic resources (including benthic reef 
habitat and water quality) from various direct or indirect development 
impacts (e.g., impacts of channel dredging, onshore development, point-
source runoff, etc.). Harvest measures are those intended to control or 
regulate the commercial or recreational catch of the species, and may 
or may not be resource conservation based. Conservation/replenishment 
measures are those intended to ensure the continuance of the fishery or 
habitat resource through various measures including setting aside no-
harvest areas, requiring culling of shell during harvest, setting up 
programs to return shells from harvested product back to reef areas, or 
natural seed movement programs intended to support either habitat or 
fishery restoration.
    State shellfish control agencies are responsible for managing 
shellfish harvesting areas for public health protection, which may 
result in permanent or temporary closures due to the presence of toxic 
algal blooms, elevated fecal coliforms and/or Vibrio spp., or chemical 
contamination. According to the Environmental Protection Agency (http://www.epa.gov/maia/html/es-condition.html), shellfishing was prohibited 
from 3 percent (3,660,000 acres, or 1,481,149 hectares) of the 
classified shellfish areas in the estuaries in the mid-Atlantic in 
2006, restricted in 5 percent (179,000 acres, or 72,438 hectares), and 
conditionally closed in 2 percent (67,000 acres, or 27,113 hectares). 
Similar closures occur in the Northeast, Southeast, and Gulf of Mexico, 
varying spatially and temporally. These restrictions may have the 
ancillary benefit of protecting some populations in chronically 
contaminated areas from harvest.
    Restoration and enhancement efforts for fisheries and conservation 
are occurring throughout the species' range, but are more common in the 
north and mid-Atlantic. According to the survey responses, in estuaries 
where restoration and enhancement efforts are occurring they are 
considered necessary to sustain populations in roughly half the 
estuaries in the mid- and south Atlantic regions (presumably, to 
support commercially viable populations). In the North Atlantic 
(specifically, Connecticut and Rhode Island) and the Gulf of Mexico, 
restoration and enhancement efforts are not necessary to sustain 
biologically viable populations but are considered important to 
maintaining a fishery and conserving ecosystem services. Many 
restoration efforts throughout the species' range have been ongoing for 
many years and have proven successful in maintaining oyster 
populations. Due to the longevity and success of many of these efforts, 
they are expected to continue into the future. Consequently, measures 
to regulate the eastern oyster have been determined to be adequate. 
Thus, we conclude that the inadequacy of existing regulatory mechanisms 
is not a significant threat that affects the continued existence of the 
eastern oyster species/subspecies.

Other Natural or Manmade Factors Affecting the Continued Existence of 
the Species

    Finally, hurricanes, harmful algal blooms, and non-native 
introductions have been identified as other possible factors affecting 
the eastern oyster throughout its range. However, none of these 
stressors are thought to have a significant impact throughout all or a 
significant portion of the range of either the eastern oyster species 
or hypothetical subspecies. Thus, we conclude that there are no other 
natural or manmade factors considered to be significant threats that 
affect the

[[Page 35393]]

continued existence of the eastern oyster species/subspecies.
Summary and Synthesis of Analysis of the Factors Identified in ESA 
Section 4(a)(1)
    While eastern oyster abundance has declined from historic highs, 
especially in the northern portion of the species' range, the eastern 
oyster is still present in all areas throughout its historic 
distribution. According to the survey results, even at the low 
abundance levels in some areas, recruitment is sufficient to maintain 
the viability of eastern oyster populations throughout the species' 
range except in a portion of the mid-Atlantic (e.g., Long Island Sound, 
Peconic Bay, Hudson Raritan Estuary). This area represents a small 
portion of the large geographic range of the species and/or 
hypothetical subspecies and would not be expected to significantly 
impact or impede larval transport and exchange to and from more 
productive areas to the north or south. The area also represents a 
minor percentage of the overall potential oyster biomass and of the 
total spawning potential of the species/hypothetical subspecies. We 
conclude that recruitment in other portions of the range is more than 
sufficient to maintain the continued existence of the species and/or 
hypothetical subspecies.
    In all cases, the analysis of all five factors indicate that the 
continued existence of the species or hypothetical subspecies is not at 
risk now or in the foreseeable future. While threats that may be 
significant at a regional or local level to the species exist, we do 
not consider any to be overwhelmingly dominant or advancing at a 
significant rate which would result in the species or hypothetical 
subspecies becoming threatened or endangered.

Listing Determination

    The ESA defines an endangered species as any species in danger of 
extinction throughout all or a significant portion of its range, and a 
threatened species as any species likely to become an endangered 
species within the foreseeable future throughout all or a significant 
portion of its range. Section 4(b)(1) of the ESA requires that the 
listing determination be based solely on the best scientific and 
commercial data available, after conducting a review of the status of 
the species and after taking into account those efforts, if any, that 
are being made to protect such species. After reviewing the best 
available scientific and commercial information for the eastern oyster, 
we have determined that neither the species nor the potential 
subspecies warrants listing as threatened or endangered at this time.
    While listing the species or hypothetical subspecies under the ESA 
is not warranted at this time, the BRT and the peer reviewers 
identified specific research and/or monitoring needs that are 
considered very important to the long-term conservation and 
preservation of the eastern oyster. These include the following: 
fishery independent surveys (quantitative stock assessments for the 
entire range); effective population size estimates; monitoring of the 
effectiveness of conservation/restoration efforts; additional genetic 
analyses to determine population structure with a focus on local or 
regional adaptations; research on proximity-recruitment relationship; 
research on effects of combined and chronic stresses including changes 
due to climate change; continued research on disease susceptibility and 
development of selectively bred disease tolerant strains; emerging role 
of endocrine disrupting pollutants; delineation of oyster habitat; 
compatibility of existing information; continued ecological risk 
associated with other oyster or other alien species introductions; 
control and abatement of threats from all sources; developmentof a 
standard monitoring protocol on a local or regional level; and research 
on the effects of changes in coastal development and demographics.

    Authority: 16 U.S.C. 1531 et seq.

    Dated: June 22, 2007.
Samuel D. Rauch III,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.
[FR Doc. E7-12564 Filed 6-27-07; 8:45 am]