[Federal Register Volume 68, Number 19 (Wednesday, January 29, 2003)]
[Proposed Rules]
[Pages 4433-4441]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-2034]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Parts 223 and 224

[I.D. 122302B]


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition to List North American Green Sturgeon as a Threatened or 
Endangered Species

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

ACTION: Notice of petition finding and availability of a status review 
document.

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SUMMARY: NMFS has completed an Endangered Species Act (ESA) status 
review for the North American green sturgeon (Acipenser medirostris). 
After reviewing the available scientific and commercial information, 
NMFS has determined that the petitioned species is comprised of two 
distinct population segments (DPSs) that qualify as species under the 
ESA, but that neither DPS warrants listing as a threatened or 
endangered species at this time. Because of remaining uncertainties 
about their population structure and status, NMFS is adding both DPSs 
to the agency's list of candidate species and will re-evaluate their 
status in 5 years provided sufficient new information becomes available 
indicating that a status review update is warranted.

DATES: The finding announced on this document was made on January 23, 
2003.

ADDRESSES: The North American green sturgeon status review and list of 
references are available by submitting a request to the Assistant 
Regional Administrator, Protected Resources Division, Southwest Region, 
NMFS, 501 West Ocean Blvd., Suite 4200, Long Beach, CA 90802-4213, or 
the Assistant Regional Administrator, Protected Resources Division, 
Northwest Region, NMFS, 525 NE Oregon Street, Suite 500, Portland, OR 
97232. The status review and other reference materials regarding this 
determination can also be obtained via the Internet at: http://www.nmfs.noaa.gov.

FOR FURTHER INFORMATION CONTACT: Craig Wingert, NMFS, Southwest Region 
(562) 980-4021, Scott Rumsey, NMFS, Northwest Region (503) 872-2791, or 
David O'Brien, NMFS, Office of Protected Resources (301) 713-1401.

SUPPLEMENTARY INFORMATION:

Petition Background

    On June 12, 2001, NMFS received a petition from the Environmental 
Protection Information Center, Center for Biological Diversity, and 
WaterKeepers Northern California requesting that NMFS list the North 
American green sturgeon (Acipenser medirostris) as either an endangered 
or threatened species under the ESA, and that critical habitat be 
designated for the species concurrently with any listing determination.

[[Page 4434]]

    The petition noted that the green sturgeon is a recognized species, 
but also indicated that until recently, geographic variation in the 
species had received little attention. Although Russian and Asian forms 
of the green sturgeon are morphologically similar to the North American 
form, the petitioners cited genetic evidence that demonstrates 
differences between the Asian and North American forms and suggesting 
they are two distinct species. In this petition, therefore, the use of 
A. medirostris referred to the North American population of the green 
sturgeon. The petitioners also noted that the stock structure of this 
species is poorly known as well, and that there may prove to be DPSs 
within this biological species as new data are gathered and analyzed.
    The petitioners indicated that the only remaining spawning 
populations of the North American green sturgeon are in the Sacramento 
and Klamath River basins in California and possibly the Rogue River, 
Oregon. The petitioners also suggest that the spawning population in 
the Klamath River basin is larger than the population in the Sacramento 
River basin. Running-ripe adults and young of the year have been 
observed in the Rogue River, but exact spawning locations have not been 
confirmed. The petitioners also stated that green sturgeon apparently 
no longer spawn in the Eel River, the South Fork Trinity River, and the 
San Joaquin River in California. The petitioners also cited recent 
declines in green sturgeon in the Umpqua River in Oregon and the Fraser 
River in Canada. The petitioners cite Musick et al. (2000) as 
indicating that each of the known or suspected spawning populations of 
green sturgeon presently contain a few hundred mature females at most.
    The petitioners concluded that the North American green sturgeon is 
at a high risk of extinction because of the reduced number and size of 
spawning populations, ongoing threats to the species from the loss and/
or degradation of habitat particularly in those river systems where 
they are known or thought to spawn, and continuing impacts to the 
species from harvest in sport fisheries or as bycatch in other 
fisheries (e.g. commercial white sturgeon fishery). Specific concerns 
regarding habitat loss and degradation cited by the petitioners include 
the construction of dams and operation of large scale water projects in 
the Sacramento, Klamath River and other coastal systems, and logging, 
agriculture, mining, road construction and urban development in coastal 
watersheds. With respect to fisheries impacts on green sturgeon, the 
petitioners cited fisheries that occur in coastal Washington and the 
Columbia River which focus on white sturgeon or salmon but take green 
sturgeon as a bycatch. Of particular concern is the potential bycatch 
of pre-reproductive individuals in these fisheries, particularly if 
this harvest is supported by the spawning populations that exist in the 
Klamath and Sacramento River basins.
    NMFS evaluated the information provided or cited in the petition 
and also reviewed other information readily available to agency 
scientists on issues related to the distribution, abundance, and 
threats to the petitioned species. On December 14, 2001, NMFS published 
a 90-day finding (66 FR 64793) that the petition presented substantial 
information that listing North American green sturgeon under the ESA 
may be warranted, and announced the initiation of a review of the 
biological status of the species.
    To ensure that the status review was complete and based on the best 
available scientific and commercial data, the 90-day finding also 
requested information and comments from the public concerning the 
status of North American green sturgeon (66 FR 64793). In addition, 
NMFS specifically requested information and comments on green sturgeon 
from State and Tribal co-managers in California, Oregon, and 
Washington. NMFS requested information on: (1) biological or other 
relevant data that may help identify DPSs of this species (e.g., age 
structure, genetics, migratory patterns, morphology, etc.); (2) the 
range, distribution, and abundance of this species, including 
information on the spawning populations of the species; (3) current or 
planned activities and their possible impact on this species (e.g., 
harvest impacts, habitat changes or alterations, etc.); and (4) efforts 
being made to protect this species in California, Oregon, Washington 
and Canada. NMFS also requested quantitative evaluations describing the 
quality and extent of freshwater, estuarine and marine habitats for 
this species, as well as information on areas that may qualify as 
critical habitat in California, Oregon, and Washington. For areas 
potentially qualifying as critical habitat, NMFS requested information 
describing (1) the activities that affect the area or could be affected 
by the designation, and (2) the economic costs and benefits of 
additional requirements of management measures likely to result from 
the designation.
    NMFS assembled a Biological Review Team (BRT) comprised of staff 
from the agency's Southwest Fisheries Science Center, Northwest 
Fisheries Science Center, and the U.S. Geological Survey. The BRT has 
reviewed the best available scientific and commercial information 
pertaining to green sturgeon from California through the Pacific 
Northwest and prepared a status review for the species (NMFS, 2002). 
This document summarizes the principal results of the green sturgeon 
status review. Copies of the BRT status review report and other 
documents relevant to this review are available online. Paper copies 
are available upon request (see ADDRESSES).

Biology and Life History of Green Sturgeon

    The green sturgeon (A. medirostris) is the most widely distributed 
member of the sturgeon family Acipenseridae. Like all sturgeon species 
it is anadromous, but it is also the most marine oriented of the 
sturgeon species. The only recently-documented green sturgeon spawning 
locations are in the Klamath, Sacramento, and Rogue rivers along the 
west coast of North America. However, green sturgeon are known to range 
in nearshore marine waters from Mexico to the Bering Sea and are 
commonly observed in bays and estuaries along the coast with 
particularly large concentrations entering the Columbia River estuary, 
Willapa Bay, and Grays Harbor during the late summer (Moyle et al., 
1992). The reasons for these concentrations are unclear, but do not 
appear to be related to spawning or feeding.
    Sturgeons in general have a life history that is susceptible to 
overharvesting and a number of species have some kind of protection or 
special status. The green sturgeon has a status designation of Special 
Concern in Canada (Houston 1988) because it has characteristics that 
make it particularly sensitive to human activities or natural events. 
Sakhalin sturgeon (A. mikadoi), a species that was at one time 
synonymized with green sturgeon, is extirpated throughout Japan, Korea, 
and China. In Russia the species is reduced in range to the Tumnin 
River where there is a hatchery. In the United States, there are five 
sturgeon species listed as threatened or endangered under the ESA: 
Shortnose sturgeon (A. brevirostrum); pallid sturgeon (Scaphirhynchus 
albus); Gulf sturgeon (A. oxyrinchus); white sturgeon, Kootenai River 
population (A. transmontanus); and Alabama sturgeon (S. suttkusi). More 
detailed information on the geographic distribution, spawning, early 
life history, ocean residence, age and growth, and feeding

[[Page 4435]]

habits of green sturgeon are presented below.
    Distribution. San Francisco Bay and its associated river systems 
contain the southern-most spawning population of green sturgeon. White 
sturgeon supports a large fishery in this area, particularly in San 
Pablo Bay, which has been extensively studied by California Department 
of Fish and Game (CDFG) since the 1940's. While green sturgeon are not 
common, they are collected incidentally in a white sturgeon trammel net 
monitoring program during most years in numbers ranging from 5 to 110 
fish. Green sturgeon juveniles are found throughout the Delta and San 
Francisco Bay.
    Green sturgeon adults and juveniles occur throughout the upper 
Sacramento River. Green sturgeon are reported to spawn in the Feather 
River, but this has not been substantiated. Green sturgeon spawning 
occurs predominately in the upper Sacramento River. Juvenile sturgeon 
have been taken annually in trapping operations at the RBDD (1995-2001) 
and at the Glenn-Colusa Irrigation District pumping facility as part of 
a monitoring program (1986-2001). All larval and juvenile sturgeon 
caught at these locations are assumed to be green sturgeon because 
juveniles collected at these sites and grown to identifiable size were 
green sturgeon. There is no documentation of green sturgeon spawning in 
the San Joaquin River at present, but there may have been spawning 
there before construction of large-scale hydropower and irrigation 
development. Young green sturgeon have been taken occasionally in the 
Santa Clara Shoal area in the San Joaquin delta but these fish likely 
originated from elsewhere, most likely the Sacramento River (CDFG 
2002).
    Green sturgeon also occur in the coastal waters of the Pacific 
Ocean off California and in coastal rivers. Small numbers have been 
taken in both Tomales Bay and Bodega Bay and a single fish has been 
taken from the Noyo River. They are regularly taken in small numbers in 
Humboldt Bay, and have been caught in coastal waters and in estuaries 
from Arcata Bay to the Oregon border. Small numbers of both adult and 
juvenile green sturgeon have been observed in the Eel River.
    The largest spawning population of green sturgeon is thought to 
occur in the Klamath River on the north coast of California, but there 
are no direct estimates of green sturgeon abundance. Adults are 
captured in the salmon gill net fisheries conducted by the Yurok and 
Hoopa Indian tribes and adults occur upstream in the Klamath to a 
natural migration barrier at Ishi Pishi Falls (rkm 107). Juvenile green 
sturgeon are captured each year on the Klamath River and have also been 
found in the lower portion of the Salmon River which is a tributary to 
the Klamath River. Adults occur in the Trinity River, a major tributary 
to the Klamath River, to Gray's Falls (rkm 69), but spawning can only 
be confirmed up to the Willow Creek trap (rkm 40). Moyle et al. (1992) 
reported no evidence of spawning in the South Fork of the Trinity 
River.
    The Rogue River in Oregon was recently confirmed as a third 
spawning area for green sturgeon (Erickson et al., 2001, Rien et al., 
2001). Based on tracking of radio-tagged adults captured in the 
estuary, extended holding sites were identified that have been 
associated with spawning in other species of sturgeon. Juvenile fish 
are taken in beach seining efforts in the estuary (Rien et al., 2001). 
Green sturgeon adults are taken in almost all of the Oregon coastal 
estuaries from the Chetco River to Nehalem Bay (EPIC et al., 2001). 
During white sturgeon tagging projects in Coos Bay (Coos River), 
Winchester Bay (Umpqua River), Yaquina Bay (Yaquina River), and 
Tillamook Bay (Tillamook River) green sturgeon have been captured and 
tagged; however, no recoveries have been reported (ODFW 2002).
    The Columbia River has supported a large white sturgeon fishery for 
many years in which green sturgeon are taken as bycatch. In the mid 
1930's before Bonneville dam, green sturgeon were found up to the 
Cascade Rapids. Green sturgeon are presently found up river to the 
Bonneville Dam (rkm 235), but are predominately found in the lower 60 
rkm. Tagging studies indicate a substantial exchange of fish between 
the Columbia River and Willapa Bay (WDFW 2002a). Willapa Bay, along 
with the Columbia River and Grays Harbor, is one of the estuaries where 
green sturgeon concentrate in summer. Generally, green sturgeon are 
more abundant than white sturgeon in Willapa Bay (Emmett et al., 1991).
    Grays Harbor in Washington is the northernmost estuary with green 
sturgeon summer concentrations and there are both tribal and commercial 
fisheries that take green sturgeon. There are no records of juveniles 
from Grays Harbor. Green sturgeon occur sporadically in small numbers 
throughout coastal Washington (WDFW 2002a) and are routinely 
encountered in the coastal Washington trawl fishery as minor incidental 
catch (WDFW 2002b). Occasionally, green sturgeon are caught in small 
coastal bays and estuaries during tribal salmon fisheries. A few green 
sturgeon are recovered in Puget Sound as incidental harvest (mostly 
trawl fisheries).
    Green sturgeon occur in small numbers along the western coast of 
Vancouver Island (Houston 1988) and the Skeena River. Historically, 
green sturgeon were not uncommon in the Fraser River (EPIC et al., 
2001). Since the collapse of the Fraser River white sturgeon fishery, 
however, green sturgeon are only taken there occasionally.
    Spawning. Green sturgeon are thought to spawn every 3 to 5 years 
(Tracy 1990). Their spawning period is March to July, with a peak in 
mid-April to mid-June (Moyle et al., 1992). Mature males range from 
139-199 cm in fork length (FL) and 15 to 30 years of age (VanEenennaam 
2002). Mature females range from 157-223 cm FL and 17 to 40 years of 
age. Most of the spawning males are 160-170 cm FL and 17-18 years old, 
while most of the spawning females are 182-192 cm FL and 27-28 years 
old.
    Green sturgeon spawning occurs in deep pools or ``holes'' in large, 
turbulent river mainstems (Moyle et al., 1992). Specific spawning 
habitat preferences are likely large cobble substrates, but may range 
from clean sand to bedrock substrates as well. Eggs are likely 
broadcast over the large cobble substrates where they settle into the 
space between the cobble. Green sturgeon females produce 60,000-140,000 
eggs (Moyle et al., 1992) and they are the largest eggs (diameter 4.34 
mm) of any sturgeon species (Cech et al., 2000). Temperatures above 20 
C are lethal to green sturgeon embryos (Cech et al., 2000).
    Green sturgeon spawning has only been documented in the Klamath, 
Sacramento (Moyle et al., 1992, CDFG 2002) and Rogue (Erickson et al., 
2001, Rien et al., 2001) rivers in recent times. The Klamath Basin is 
thought to support the largest green sturgeon spawning population 
(Moyle et al., 1992). In the Klamath River, breaching and other 
suspected sturgeon courtship behaviors have been observed in ``The 
Sturgeon Hole'' upstream of Orleans (rkm 96). Larvae and juveniles are 
caught in the Big Bar trap (rkm 80) on the Klamath and in the Willow 
Creek trap (rkm 40) on the Trinity. Numbers at both traps have a peak 
in July (Healey 1973).
    In the Sacramento River, green sturgeon spawn in late spring and 
early summer above Hamilton City and perhaps as far upstream as Keswick 
Dam (CDFG 2002). The opening of the Red Bluff Diversion Dam (RBDD) 
gates to improve winter-run chinook upstream and downstream passage is 
believed to have provided a substantial

[[Page 4436]]

increase in spawning habitat for green sturgeon in the upper Sacramento 
River. The gates were first opened in 1986 and the current pattern of 
operation began in 1992-93. Juvenile green sturgeon are taken in traps 
at the RBDD and the Glenn Colusa Irrigation District's (GCID) facility 
in Hamilton City, primarily in the months of May through August. Peak 
counts occur in the months of June and July.
    Green sturgeon spawning has been recently documented in the Rogue 
River (Erickson et al., 2001, Rien et al., 2001). Adult fish were 
radio-tagged in the estuary during May-June 2000. After release, tagged 
ripe fish moved up the Rogue River to spawn, while non-reproductive 
fish remained close to the tagging site. Spawning fish spent more than 
6 months in freshwater and traveled as far as rkm 39. All tagged 
individuals emigrated from freshwater during fall and winter when water 
temperatures fell below 10 C. Juvenile green sturgeon have been taken 
in beach seines in the Rogue River estuary from April until the end of 
November (Rien et al., 2001).
    Apparently, green sturgeon no longer spawn in some river systems 
where they once did (CDFG 2002). Juvenile green sturgeon were captured 
in the Eel River in traps at Rio Dell (rkm 20) and Dos Rios (rkm 191) 
during the period from 1967 to 1970 (Puckett 1976). Single or small 
numbers of adult green sturgeon are also observed periodically in the 
Eel River. Similarly, green sturgeon are reported to have spawned in 
the South Fork Trinity River, but apparently no longer do so due to 
extensive sedimentation from the 1964 flood (Moyle et al., 1992). The 
validity of reports of green sturgeon spawning in the Umpqua River is 
unclear (Lauman et al., 1972) and the possibility of current spawning 
activity is being investigated (ODFW 2002).
    Early Life History. Green sturgeon larvae first feed at 10 days 
post hatch, and metamorphosis to the juvenile stage is complete at 45 
days. Larvae grow fast, reaching a length of 66 mm and a weight of 1.8 
g in 3 weeks of exogenous feeding. Juveniles averaged 29 mm at the peak 
of occurrence in June-July at the RBDD fish trap and 36 mm at their 
peak abundance in July at the GCID trap. These growth rates are 
consistent with rapid juvenile growth to 300 mm in 1 year and to over 
600 mm within 2-3 years for the Klamath River (Nakamoto et al., 1995). 
Juveniles appear to spend 1 to 3 years in freshwater before they enter 
the ocean (Nakamoto et al., 1995).
    Ocean Residence. Green sturgeon disperse widely in the ocean after 
their out-migration from freshwater (Moyle et al., 1992). Tagged green 
sturgeon from the Sacramento and Columbia Rivers are primarily captured 
to the north in coastal and estuarine waters, with some fish tagged in 
the Columbia being recaptured as far north as British Columbia (WDFW 
2002a). While there is some bias associated with recovery of tagged 
fish through commercial fishing, the pattern of a northern migration is 
supported by the large concentration of green sturgeon in the Columbia 
River estuary, Willapa Bay, and Grays Harbor which peaks in August. 
These fish tend to be immature; however, mature fish and at least one 
ripe fish have been found in the lower Columbia River (WDFW 2002a). 
Genetic evidence suggests that Columbia River green sturgeon are a 
mixture of fish from at least the Sacramento, Klamath, and Rogue Rivers 
(Israel et al., 2002). The reasons for the concentration of green 
sturgeon in Oregon and Washington estuaries during the summer are 
unknown as there is no known spawning in these rivers and all stomachs 
examined to date have been empty (Beamesderfer 2000).
    Age and Growth. Green sturgeon is a long-lived, slow-growing 
species as are all sturgeon species (Nakamoto et al., 1995, Farr et 
al., 2002). Size-at-age is consistently smaller for fish from the 
Klamath River (Nakamoto et al., 1995) in comparison to fish from Oregon 
until around age 25, but thereafter the pattern is reversed. This could 
be the result of actual differences in growth or in ageing techniques. 
The asymptotic length for Klamath fish of 218 cm is close to the 
maximum observed size of 230 cm reported by Moyle et al. (1992), but 
substantially larger than for fish in Oregon (females 182 cm, males 168 
cm).
    Feeding. Little is known about green sturgeon feeding. Adults in 
the Sacramento-San Joaquin delta feed on benthic invertebrates 
including shrimp, mollusks, amphipods, and even small fish (Moyle et 
al., 1992). Juveniles in the Sacramento-San Joaquin Delta feed on 
opossum shrimp and amphipods (Radtke 1966). One hundred and twenty-one 
green sturgeon stomach samples from the Columbia River gill-net fishery 
were empty with the exception of one fish, while all white sturgeon 
stomachs contained digested material (ODFW 2002).

Consideration as a ``Species'' Under the ESA

    To qualify for listing as a threatened or endangered species the 
petitioned North American green sturgeon must be considered a species 
under the ESA. Section 3(16) of the ESA (16 U.S.C. 1532(16)) expands 
the definition of a ``species'' under the ESA to include any subspecies 
or any ``distinct population segment (DPS) of any species of vertebrate 
fish or wildlife which interbreeds when mature.'' On February 7, 1996, 
the U.S. Fish and Wildlife Service and NMFS adopted a policy to clarify 
their interpretation of the phrase ``distinct population segment of any 
species of vertebrate fish or wildlife'' for purposes of listing, 
delisting, and reclassifying species under the ESA (61 FR 4722). This 
joint policy identifies two elements that must be considered when 
making DPS determinations: (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 species or subspecies to which it belongs.
    According to the joint policy, a population segment 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; or (2) it is delimited by international 
governmental boundaries across which there is a significant difference 
in exploitation control, habitat management, or conservation status. 
Quantitative measures of genetic or morphological discontinuity may 
provide evidence of this separation.
    The joint policy states that the following are some of the 
considerations that may be used when determining the significance of a 
population segment to the taxon to which it belongs: (1) persistence of 
the discrete population in an unusual or unique ecological setting for 
the taxon; (2) evidence that the loss of the discrete population 
segment would cause a significant gap in the taxon's range; (3) 
evidence that the discrete population segment represents the only 
surviving natural occurrence of a taxon that may be more abundant 
elsewhere; or (4) evidence that the discrete population segment has 
marked genetic differences from other populations of the species.

Species Status and DPS Structure

    Species Status. Green sturgeon that occur within U.S. and Canadian 
waters are a geographically isolated and genetically distinct species. 
The North American form was initially considered conspecific with the 
previously described Asian species, Sakhalin sturgeon (A. mikadoi), and 
the two forms were synonymized (Berg, 1948). More recent molecular data 
on three mitochondrial genes, however, show great differences between 
the North

[[Page 4437]]

American and Asian forms of green sturgeon (Birstein and DeSalle, 
1998), and consequently, these two forms are now considered separate 
species.
    The petitioned action requested that North American green sturgeon 
be listed as a threatened or endangered species, but the petitioners 
also recognized that this species could be comprised of multiple DPSs. 
For this reason and because other sturgeon species have been divided 
into multiple DPSs, NMFS' BRT assessed the best available scientific 
information concerning the population structure of green sturgeon in 
North America in an effort to determine whether or not the biological 
species was comprised of one or more DPSs. Based on a review of the 
best available scientific information, NMFS has determined that North 
American green sturgeon are comprised of two populations that are both 
discrete and significant as defined in the DPS policy and are therefore 
DPSs. One is a northern DPS consisting of coastal populations ranging 
from the Eel River northward. The second is a southern DPS that 
includes any coastal or central valley populations south of the Eel 
River, with the only known population being in the Sacramento River. 
These DPSs and the information used to characterize them are summarized 
below, and discussed in greater detail in the green sturgeon status 
review (NMFS 2002).
    Discreteness: Genetic data were analyzed from 66 green sturgeon 
sampled from the Klamath River in 1998, 46 fish sampled from San Pablo 
Bay in 2001, 15 sampled from the Rogue River in 2000, and 29 sampled 
from the Columbia River estuary in 1995. The analysis on this genetic 
data, while preliminary, suggest that green sturgeon from the Klamath 
River are genetically distinct from fish in San Pablo Bay, and that 
green sturgeon from the Klamath and Rogue River are similar to each 
other (Israel et al., 2002). Green sturgeon from the Columbia River 
appear to be a mixture of fish from the San Pablo Bay, Klamath, and 
Rogue populations. Israel et al. (2002) suggest that the genetic data 
indicate that spawning could be occurring in some other unknown 
locations; however, this preliminary conclusion could change if larger 
samples were analyzed or if samples were collected from multiple years. 
While preliminary, the best available genetic data indicates that there 
are substantial genetic differences at least between the geographically 
separated Klamath River and San Pablo Bay populations of green 
sturgeon.
    Sturgeon species exhibit fidelity to their spawning sites so they 
have a general pattern of multiple DPSs. Sturgeon are known to have 
strong homing capabilities which leads to high spawning site fidelity 
(Bemis and Kynard, 1997). Because preliminary genetic data indicate 
that the Sacramento River population is different from the Klamath and 
Rogue River populations, and because sturgeon tend to exhibit high 
spawning site fidelity, NMFS has determined that the two green sturgeon 
populations are ``discrete'' as defined in the DPS policy.
    Significance: The genetic information described above indicates 
that the northen and southern populations are ``significant'' as 
defined in the DPS policy. In addition to the genetic information, 
there is other information indicating that these DPSs are significant. 
First, each DPS occupies unusual or unique ecological settings for the 
species as a whole. This is evidenced by the fact that spawning 
populations of each DPS are found in separate and distinct 
Environmental Protection Agency ecoregions that have been identified 
based on soil content, topography, climate, potential vegetation, and 
land use (Omernik 1987). The geographic range of the northern DPS 
occurs largely within the Coastal Range ecoregion which extends from 
the Olympic Peninsula southward through the Coast Range and Klamath 
Mountains to the San Francisco Bay area. In contrast, the southern DPS 
occurs largely within the Central California Valley ecoregion which 
includes the Sacramento and San Joaquin Rivers. Second, the loss of 
either of these DPSs would result in a significant gap in the range of 
the species given the known distribution of spawning populations.
    The identification of two DPSs and the geographic separation of the 
two DPSs at the Eel River should be considered provisional and subject 
to revision as more genetic and life history information is gathered on 
green sturgeon. Although NMFS believes that the green sturgeon is 
comprised of at least these two DPSs, additional DPSs may be delineated 
when more genetic and life history information is collected and 
analyzed. Similarly, the Eel River boundary between these two DPSs is 
based largely on geography and may be modified based on new 
information.

Status of Green Sturgeon DPSs

    In assessing the status of the northern and southern DPSs, NMFS 
evaluated the available literature, information obtained in response to 
the 90-day finding request for information, and both qualitative and 
quantitative information provided by state and Tribal co-managers from 
California, Oregon, and Washington. The quantitative information was 
primarily time series of harvest (catch and catch-per-unit-effort 
(CPUE)) data from fishery agencies in Oregon and Washington, and from 
Tribal fishery managers in the Klamath River basin.

Northern Green Sturgeon DPS

    Information relevant to assessing the abundance and/or population 
trends of green sturgeon in this DPS is limited. The status review for 
green sturgeon examined fisheries harvest data from the Yurok tribal 
fishery in the Klamath River and the commercial sturgeon fishery in the 
Columbia River in an effort to assess trends in abundance over time and 
population status (NMFS 2002). The time series of catch and CPUE data 
for the Yurok tribal fishery was considered the most representative 
available population measure for green sturgeon in general and this DPS 
in particular because the data are based on a spawning population in 
the DPS rather than a summer concentration of non-spawning fish from a 
mixture of spawning populations such as is the case in the Columbia 
River. Both data series are fishery-dependent and suffer from problems 
associated with changing regulations and effort levels.
    Catch and CPUE data are available for the Yurok tribal fishery for 
the period 1984-2001, and it is the data set least impacted by 
regulatory changes. A qualitative examination of the data suggests that 
catch has increased slightly over time and that CPUE is stable or has 
slightly decreased over time. However, these trends are not 
statistically significant. The length-frequency data of harvested green 
sturgeon was also examined to determine if there was any evidence that 
harvest was affecting the size structure of the population. Although 
the sample sizes were small, there was no evidence of any trend in the 
available data suggesting that larger fish were being removed from the 
population or that the size structure of the population has been 
altered by this or other fisheries.
    The Columbia River commercial harvest data represents the longest 
available green sturgeon time series, but it is difficult to interpret 
since the harvest occurs on a summer concentration of non-spawning fish 
that are thought to originate from multiple spawning populations. 
Regulations were significantly modified in 1993, so the analysis of 
trends was only conducted on catch data from 1960-1992. Catch over this 
time period may have been affected not only by changes in regulations 
and effort but also by

[[Page 4438]]

unknown factors controlling the summer concentration of green sturgeon 
in the Columbia River. The catch data were analyzed to determine if 
there were any trends in data and if they were significant. Length 
frequency of the catch data was also examined over the period of 1985-
2001 to see if the fishery was affecting the size structure of fish 
that concentrate in the Columbia River. Analysis of the data suggests 
that catch in the Columbia River has increased slightly over time; 
however, the trend was not statistically significant. In contrast, Rein 
(2002b) analyzed CPUE data for green sturgeon in the lower Columbia 
River commercial fishery over the same period of time (1981-1993) and 
found there was a statistically significant increasing trend. There was 
little evidence of a trend in the length-frequency distributions of 
catch over time. However, there does appear to have been an increase in 
the average length of green sturgeon taken in the fishery over the past 
few years, possibly suggesting that a strong year class is moving 
through the fishery.
    The status review identified potential risk factors for the 
northern green sturgeon DPS including harvest bycatch in several 
fisheries, the concentration of spawning in the Klamath River, the loss 
of historical spawning habitat, and the lack of adequate abundance and 
population trend data (NMFS, 2002). While there is some information 
relevant to harvest bycatch, limited information is available about the 
distribution of historical and current spawning activity, and the loss 
of spawning habitat. The lack of adequate abundance and population 
trend data is of concern because it is difficult to assess the status 
of the population without such data. As a result, there is considerable 
uncertainty regarding the extent to which these factors affect the 
overall level of risk faced by this DPS.
    The Klamath River is thought to support most of the total spawning 
population in this DPS and there is concern that this could increase 
the vulnerability of the DPS to catastrophic events. However, the 
extent to which spawning is concentrated in the Klamath River is not 
well documented and there is limited information on the extent and 
magnitude of spawning elsewhere in the DPS. Recent information, for 
example, has documented spawning in the Rogue River (Rein et al., 2001) 
and the possibility of spawning in the Umpqua River is also being 
investigated (ODFW 2002). Further research and monitoring in these and 
other coastal watersheds may provide new information about the 
magnitude and geographical extent of current spawning within this DPS 
and the importance of the spawning population in the Klamath River. 
Historical accounts, and what little data are available, suggest there 
has been a loss of spawning habitat in the Eel River and South Fork 
Trinity Rivers due to anthropogenic changes and natural events that 
increased sedimentation (CDFG, 2002). At the same time, it is uncertain 
to what extent the loss or reduction of spawning in the Eel and South 
Fork Trinity Rivers has affected this DPS or the extent to which it 
places the DPS at greater risk since there is virtually no information 
documenting the magnitude and extent of spawning that historically 
occurred in either system. Although spawning apparently no longer 
occurs in the South Fork Trinity, there is recent evidence of limited 
green sturgeon spawning in the Eel River based on the collection of 
both adult and juvenile fish in the mid 1990s (CDFG, 2002).
    The status review examined the available harvest bycatch data in an 
effort to assess the effects of harvest on green sturgeon in this DPS 
and in general, but concluded it was not possible to directly assess 
harvest impacts because of two factors. First, most of the harvest 
occurs on summer concentrations of fish in the Columbia River and 
coastal Washington estuaries that are comprised of fish from a mixture 
of spawning populations and both DPSs. Second, there is no estimate of 
the size for any of the known spawning populations that occur in either 
DPS. Although direct assessment of harvest impacts on this DPS may not 
be possible with the available data, a qualitative assessment of green 
sturgeon bycatch data for various fisheries since the mid 1980s 
suggests that the impacts to green sturgeon from harvest bycatch have 
been greatly reduced in recent years.
    Harvest of green sturgeon occurs almost entirely as bycatch in 
commercial fisheries for white sturgeon in Oregon and Washington, as 
well as a variety of smaller tribal fisheries (e.g. Klamath River 
tribal fisheries). Green sturgeon harvest data for these fisheries were 
summarized in the status review for the years 1985-2001, and over this 
period the vast majority of the total harvest was taken in the Columbia 
River sport and commercial fisheries (51 percent) and the various 
Washington coastal fisheries (28 percent). The remainder of the total 
harvest occurred in the coastal Oregon fisheries and the Klamath River 
tribal fisheries. Since the mid 1980s, the total annual harvest of 
green sturgeon in all of these fisheries has declined nearly six fold 
from approximately 6,870 fish/year in 1985-1989 to approximately 1,190 
fish/year in 1991-2001 (Table 1 in NMFS 2002). In 2001, the total 
harvest in all fisheries declined to less than 800 fish, with 
approximately equal numbers of fish taken in the Columbia River, 
coastal Washington, and Klamath River fisheries. This overall decline 
in green sturgeon harvest has been driven principally by a major 
reduction in the harvest from the Columbia River and Washington coastal 
fisheries since the mid 1990s.
    The average length of green sturgeon caught in the Columbia River 
commercial fishery has been increasing since 1990, with the largest 
average size of fish occurring in the last five years. This trend may 
indicate a larger average size of fish due to reduced exploitation, a 
strong year-class moving through the fishery, or a reduction of small 
fish due to reduced or failed recruitment.
    Much of the harvest reduction in recent years is due to 
increasingly restrictive regulations in the Columbia River fisheries 
(Appendix 1, Tables 1 and 2 in NMFS 2002). The Columbia River fishery 
is currently managed through a joint Washington and Oregon accord to 
manage white sturgeon. Probably the most important regulation for 
protecting sturgeon was the introduction of slot limits starting in 
1950 for both the sport and commercial fisheries. Beginning in 1950 and 
continuing through 1997-98 when the slot limits were last changed, they 
have become increasingly restrictive and protective of both green and 
white sturgeon. The Columbia River sturgeon fishery is currently 
operating under a March 2000 agreement covering a three-year period 
through 2002. The green sturgeon regulations under this agreement 
include: a recreational size limit of 42-60 inches (107-152 cm) with 
one fish per day and 10 fish per year bag limits, with barbless hooks 
required; a commercial size limit of 48-66 inches (122-168 cm); and no 
green sturgeon-only commercial seasons (green sturgeon are only taken 
as bycatch during white sturgeon seasons, provided the green sturgeon 
catch does not exceed recent harvest levels). Commercial bycatch of 
green sturgeon occurs predominantly during the early fall (August) 
salmon and white sturgeon fisheries, when the green sturgeon have 
migrated into the estuary and lower mainstem of the Columbia River.
    In 2001, sturgeon retention was prohibited during the early-fall 
target chinook commercial season after the preseason catch expectation 
for white sturgeon was exceeded in early August. Sturgeon retention was 
prohibited in

[[Page 4439]]

mainstem commercial fisheries through the remainder of the fall fishing 
period. White sturgeon population estimates for 2002 did not increase 
as expected, and in December of 2001 the Compact adopted reduced catch 
guidelines for 2002 as a management buffer and to compensate for catch 
overages that occurred in 2001. In 2002, the Compact prohibited 
retention of green sturgeon during August fisheries and allowed 
retention during September and October fisheries. This management 
action provided flexibility for shaping September and October salmon 
fisheries and allowed the commercial fishery access to their allocation 
of white sturgeon without any target sturgeon seasons, further 
minimizing green sturgeon bycatch. The Compact will meet in January 
2003 to review its sturgeon fishery management agreement and it is 
expected that continued efforts will be taken to minimize green 
sturgeon bycatch.
    Ocean and coastal estuarine fisheries in Washington and Oregon 
accounted for approximately 28 percent and 8 percent, respectively, of 
the total green sturgeon harvest bycatch in the period between 1985-
2001. Since the mid to late 1990's, however, the overall catch of green 
sturgeon in these fisheries has also declined substantially, most 
likely due to changes in fishing regulations. White and green sturgeon 
fisheries in Oregon coastal areas are managed under size and bag limit 
regulations consistent with the lower Columbia River regulations.
    Non-tribal harvest impacts on green sturgeon in coastal rivers of 
California are considered to be minimal (CDFG, 2002). Commercial 
fishing for green sturgeon (and white sturgeon) has been prohibited 
throughout the state since the early 1900s. Recreational fishing for 
green sturgeon has been prohibited since the early 1990s in virtually 
all coastal watersheds where green sturgeon are known to occur from the 
Eel River northward to the Oregon border, including the Klamath-Trinity 
basin. The Klamath River tribal (Yurok and Hoopa Tribes) fisheries 
accounted for about 8 percent of the total green sturgeon harvest that 
occurred between 1985-2001, with an average catch of approximately 260 
fish per year. These Tribal fisheries do impact a spawning population 
in the Klamath River, but the available data for the Yurok Tribal 
fishery show that both catch and CPUE have been very stable since 1985, 
with no evidence of a decline. There is no evidence from the available 
length-frequency data for harvested green sturgeon that larger fish 
have been removed from the population or that the size structure of the 
population has been altered by this or other fisheries.
    Conclusion: The available population information for green sturgeon 
in the northern DPS does not provide any evidence that the abundance of 
green sturgeon in this DPS is declining. In particular, the fishery-
dependent harvest data from the Yurok tribal fishery show no evidence 
that catch or CPUE are declining, or that large fish are being removed 
from that spawning population. Despite this information, NMFS' BRT was 
uncertain about the status of green sturgeon in this DPS because no 
direct fisheries-independent population estimates were available. For 
this reason, the BRT believes it is essential that immediate efforts be 
undertaken to implement direct monitoring of green sturgeon in this 
DPS. There are some risk factors of potential concern for this DPS, 
most notably bycatch harvest in various fisheries; however, there is 
uncertainty about the overall level of risk facing this DPS. In the 
case of harvest bycatch for which there is the most information, it is 
not possible to directly assess the impact of harvest on green sturgeon 
in this DPS. Nevertheless, the available data shows that overall green 
sturgeon harvest has declined substantially since the mid 1980s due to 
increasingly restrictive harvest management measures, suggesting that 
risk from harvest has been also reduced. Although the risk to green 
sturgeon from harvest bycatch may be declining, NMFS believes it may be 
prudent for fisheries managers to continue recent conservative 
management measures as well as consider additional harvest protections 
until population monitoring information can be obtained to assess the 
status of this DPS with greater certainty. Based on a review of the 
best available information, NMFS concludes that the northern green 
sturgeon DPS is not presently in danger of extinction nor is it likely 
to become so in the foreseeable future.

Southern Green Sturgeon DPS

    The only data relevant to assessing the abundance and/or population 
trends of green sturgeon in this DPS are estimates of green sturgeon 
abundance made by the California Department of Fish and Game in San 
Pablo Bay incidental to monitoring of white sturgeon (CDFG, 2002). 
Tagging experiments have been conducted irregularly since 1954, but 
since 1990 tagging has been conducted for two years consecutively and 
then the next two are skipped. Over this period, a total of 536 green 
sturgeon were captured and 233 fish were tagged. The green sturgeon 
estimate is obtained by multiplying the ratio of legal-size (earlier 
minimum slot limits of 102 cm) green sturgeon to legal-size white 
sturgeon caught in the tagging program by the legal-size white sturgeon 
population estimate. Although this is a fishery-independent estimate of 
green sturgeon abundance, there are a number of problems associated 
with these estimates; the most important being the assumption that both 
species are equally vulnerable to the sampling gear. Since green 
sturgeon concentrate in estuaries only during the summer and white 
sturgeon remain in estuaries year round, the temporal and spatial 
vulnerabilities of the two species are likely different. In addition, 
the estimate is based on a summer concentration of fish rather than a 
spawning population, and varying levels of tag recovery effort.
    The status review examined the available time series of these 
population estimates qualitatively and also looked for statistically 
significant trends in the data. A qualitative examination of the time 
series suggests abundance has been stable, except for a substantial 
increase in the 2001 abundance estimate. The 2001 abundance estimate 
was 8,421 fish which is approximately four times higher than any 
previous estimate. Estimates for the years prior to 2001 range from 
several hundred to approximately 2,000 fish (see Figure 11 and Table 2 
in NMFS 2002). The data suggest an increasing trend in green sturgeon 
abundance, but the increase was not statistically significant even with 
the large increase in the 2001 estimate. Although the sample sizes are 
small, the average size of green sturgeon tagged as part of this 
population estimation program in San Pablo was generally stable and 
showed no apparent trend over time.
    NMFS' BRT identified several potential threats or risk factors for 
the southern green sturgeon DPS (NMFS, 2002). These include: harvest 
bycatch concerns; the concentration of spawning in the Sacramento River 
and the apparent small population size; loss of spawning habitat, lack 
of adequate population abundance data; potentially lethal water 
temperatures for larval green sturgeon; entrainment by water projects 
in the central valley; and the adverse effects of toxic materials and 
exotic species. Although the BRT expressed concerns about these 
potential risk factors, there is considerable uncertainty regarding 
their significance or effects on the southern green sturgeon DPS.
    Spawning in this DPS does appear to be concentrated in the upper 
Sacramento River at present. Since the

[[Page 4440]]

early 1990s it appears that green sturgeon have expanded into 
additional spawning habitat in the upper Sacramento above Hamilton City 
due to the re-operation of the RBDD (CDFG, 2002). There is uncertainty 
about the abundance of green sturgeon and the size of the spawning 
population in the Sacramento River. The CDFG population estimates for 
San Pablo Bay, which presumably include Sacramento River spawners, are 
in the range of hundreds to thousands of fish, but there are several 
problems with the estimates that make them difficult to interpret or 
rely upon. Similarly, there are no historical estimates of spawning 
population abundance available to make an assessment of the extent to 
which spawning populations have declined. The lack of population 
monitoring data is clearly problematic, but it is not a risk factor 
directly affecting the status of the DPS.
    According to the CDFG, there is no evidence that green sturgeon 
historically spawned in the San Joaquin River and juveniles that have 
been found in the lower San Joaquin River are most likely from the 
spawning population in the Sacramento River (CDFG, 2002). It is 
uncertain whether green sturgeon ever spawned in the upper Sacramento 
River above Shasta Dam, but CDFG has speculated that they may have 
based on the apparent expansion of spawning above Hamilton City in the 
early 1990s when RBDD was re-operated (CDFG, 2002). The most likely 
loss of historical spawning habitat for green sturgeon in the central 
valley may be in the Feather River as a result dam construction and 
warm water releases (CDFG, 2002), but anecdotal evidence suggests that 
adult green sturgeon still occur there in high flow years, presumably 
for spawning. Based on this information, it is uncertain how much green 
sturgeon spawning habitat historically occurred in the central valley 
or how much has been lost, and whether or not lost spawning habitat is 
a significant risk factor for this DPS.
    The state and Federal pumping facilities in the Sacramento-San 
Joaquin Delta export water from the Delta and in the process entrain 
many fish species including juvenile green sturgeon which are salvaged 
and returned to the Delta. Expanded estimates of salvage are made 
annually by CDFG and these data have been collected and compiled since 
1968 at the state facility and since 1981 at the Federal facility. The 
status review qualitatively reviewed the expanded salvage data for the 
available time series to determine whether there were any trends. The 
data series indicates that salvage (an indicator of entrainment) has 
varied substantially over time, but was much higher prior to the mid-
1980s. From the mid-1980s to present, salvage declined substantially at 
both facilities and has remained very low thereafter. Limited length-
frequency data indicates that only juvenile green sturgeon were 
salvaged at the two facilities. Interpretation of these data is 
difficult since there have been problems with species identification 
(distinguishing white and green sturgeon) and the expanded salvage 
estimates are based on actual counts from brief sampling periods (CDFG 
2002). Given the low level of entrainment and salvage that has occurred 
since the mid-1980s and the problems with interpreting the available 
data, it is uncertain to what extent water exports and the associated 
entrainment of green sturgeon is a risk factor for this DPS. In the 
case of white sturgeon, however, year class strength is related to 
freshwater flows in late winter and spring rather than Delta exports 
(CDFG 2002). If this is the case for green sturgeon, which is more 
marine oriented than white sturgeon, then Delta exports are not likely 
to be an important risk factor.
    The introduction of exotic species in the San Francisco Bay estuary 
is an ongoing problem, but the most likely effect on green sturgeon is 
through changes in trophic interactions (CDFG, 2002). For example, the 
overbite clam, which first was observed in the Bay in 1988, is now the 
most common food item of white sturgeon and has been found in the diet 
of green sturgeon (CDFG, 2002). This species may be replacing other 
clam species in the diet of white and possibly green sturgeon, but it 
is not possible to assess the impacts of such changes at present. 
Assessing the impacts of such trophic changes and the extent to which 
they increase risks to green sturgeon in this DPS will require 
additional information on the comparative trophic benefits of these new 
prey and information on the extent to which they bioaccumulate 
contaminants.
    There is no specific information available regarding contaminant 
loads or impacts on green sturgeon, although there is information on 
contaminant loads for white sturgeon (CDFG 2002). For example, there is 
evidence that white sturgeon may have contained high Polychlorinated 
Biphenyl (PCB) levels in the past (Kohlhorst, 1980), though more recent 
data show lower levels of contamination suggesting that earlier data 
may have been incorrect (CDFG, 2002). There is also evidence that white 
sturgeon in the estuary accumulate selenium, but tissue concentrations 
have varied over time without a trend and do not seem to be size 
related (White et al., 1989). Given the available information, it is 
uncertain to what extent green sturgeon are impacted by contaminants in 
this DPS. Based on the fact that white sturgeon spend more time in the 
estuary and green sturgeon are more marine oriented, CDFG suggests that 
green sturgeon are probably less vulnerable than white sturgeon to the 
effects of contaminant bioaccumulation in the San Francisco Bay estuary 
(CDFG, 2002).
    Concerns were raised in the status review that summer temperatures 
in the Sacramento River were near the lethal limits for larval green 
sturgeon; however, there is no direct evidence that elevated 
temperatures are adversely affecting spawning and larval development. 
In the Sacramento River, green sturgeon are thought to spawn in the 
spring and summer primarily from Hamilton City to as far upstream as 
perhaps Keswick Dam (NMFS, 2002; CDFG, 2002). Re-operation of RBDD in 
the early 1990s to improve upstream passage for winter-run chinook is 
also thought to have provided a substantial increase in green sturgeon 
spawning habitat above the facility (CDFG, 2002). Spawning of green 
sturgeon in the upper Sacramento River above the RBDD is supported by 
the annual collection of juvenile green sturgeon in fish trapping 
operations at the RBDD (1995-2001) and the Glenn-Colusa Irrigation 
District (1986-2001) between the months of May and August (see Figures 
13 and 14 in NMFS 2002). Since the early 1990s, significant efforts and 
measures have been implemented by the Bureau of Reclamation and NMFS to 
control water temperatures in the upper Sacramento River between the 
RBDD and Keswick dam in the late spring and early summer so that 
winter-run chinook salmon can successfully reproduce there. Under the 
current protocols, water temperatures upstream from RBDD are generally 
controlled by releases from Shasta and Keswick Dams so that they do not 
exceed 56 degrees Farenheit (or 13.3 degrees Centigrade) from mid April 
through the end of September. This period of temperature control 
appears to coincide with green sturgeon spawning, egg incubation, and 
larval development in the upper river, and therefore, the temperature 
control efforts for winter-run chinook are likely to benefit and 
protect green sturgeon as well. Temperatures cannot be controlled 
downstream of RBDD or in the Sacramento-San Joaquin Delta, so elevated 
temperatures could potentially

[[Page 4441]]

affect green sturgeon larval development in those areas.
    Harvest impacts on green sturgeon in this DPS, at least from 
fisheries in California, are thought to be minimal. Commercial fishing 
for green sturgeon (and white sturgeon) has been prohibited in 
California since the early 1900s. Direct recreational harvest does 
occur, primarily in San Pablo Bay, but the total harvest is thought to 
be very small (CDFG 2002). In addition, green sturgeon are protected by 
slot limits, very restrictive take limits, and a seasonal closure in 
central San Francisco Bay during the herring spawning season (January 
through March). Based on tagging studies conducted by CDFG, green 
sturgeon tagged in San Pablo Bay undertake extensive ocean migrations 
and are recaptured in commercial and recreational fisheries in both 
Oregon and Washington (CDFG, 2002; NMFS, 2002). Although there are 
harvest bycatch data for green sturgeon in these fisheries, it is not 
possible with the available information to directly assess the impact 
on green sturgeon in the southern DPS. In order to assess direct 
harvest impacts on this DPS, information is needed on the actual number 
of fish taken in these fisheries that originate from the Sacramento 
River spawning population as well as good estimates of the size of the 
Sacramento River population. These data are not currently available. 
Although direct harvest impacts on this DPS from the fisheries in 
Oregon and Washington cannot be determined at this time, the available 
harvest information for these fisheries suggests that overall harvest 
and, therefore, harvest impacts to green sturgeon have declined 
steadily since the mid 1980s.
    Conclusion: There is no evidence from the available San Pablo Bay 
population information that green sturgeon abundance in the southern 
DPS is declining. Nevertheless, NMFS' BRT was uncertain about the 
status of green sturgeon in this DPS because the method of deriving 
population estimates involves numerous assumptions and there are no 
direct measures of population abundance. For these reasons, the BRT 
believes it is essential that immediate efforts be undertaken to 
implement population monitoring for this DPS using methods that 
directly assess population status. There is a great deal of uncertainty 
regarding the effects of potential risk factors on green sturgeon in 
this DPS. While there is some information on harvest bycatch impacts, 
it appears most of the identified risk factors are not well documented 
or are only suspected to be risk factors. Examples of the latter 
include entrainment at the Delta water export facilities, impacts from 
exotic species introductions, impacts from contaminants, and lethal 
water temperatures. In the case of harvest bycatch for which there is 
the most information and perhaps the greatest concern, it is not 
possible to directly assess the impact of harvest on green sturgeon in 
this DPS. Nevertheless, direct harvest appears to be limited in 
California and harvest from fisheries in Oregon and Washington has 
declined substantially since the mid 1980s and even more so since the 
mid 1990s due to increasingly restrictive harvest management measures. 
These harvest reductions and associated restrictive management measures 
suggest that risk to green sturgeon from harvest bycatch has been 
reduced. Although the risk to green sturgeon from bycatch harvest may 
be declining, NMFS believes it may be prudent to consider additional 
harvest protections until population monitoring information can be 
obtained to assess the status of this DPS with greater certainty. Based 
on a review of the best available information, NMFS concludes that the 
southern green sturgeon DPS is not presently in danger of extinction 
nor is it likely to become so in the foreseeable future.

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 green sturgeon, NMFS concludes that the species is 
comprised of two DPSs that qualify as species under the ESA: (1) a 
northern coastal DPS consisting of populations in coastal watersheds 
northward of, and including, the Eel River, and (2) a southern DPS 
consisting of coastal or central valley populations south of the Eel 
River, with the only known population in the Sacramento River. 
Additional green sturgeon DPSs may be identified with further genetic 
analysis and the boundaries of these two DPS may also be modified. 
After assessing the risk of extinction faced by each DPS, NMFS further 
determines that neither the northern or southern green sturgeon DPSs 
warrant listing as threatened or endangered species at this time.
    Because of uncertainties in the structure and status of the DPSs, 
NMFS will add both DPSs to the agency's list of candidate species. 
Additional information is expected to be collected over the next 
several years and NMFS intends to reevaluate the status of green 
sturgeon in five years provided sufficient new information becomes 
available indicating that a status review update is warranted.

References

    A list of references is available upon request (see ADDRESSES).

Authority

    The authority for this section is the ESA, as amended (16 U.S.C. et 
seq.).

    Dated: January 23, 2003.
Rebecca Lent,
Deputy Assistant Administrator for Regulatory Programs, National Marine 
Fisheries Service.
[FR Doc. 03-2034 Filed 1-28-03; 8:45 am]
BILLING CODE 3510-22-S