Shellfish Assessment- Kodiak Laboratory
Data assembly for the 2002 eastern Bering Sea survey is completed, computations
of abundance were finished by 16 August, and all guideline harvest levels
have been determined by joint NMFS - ADF&G analysis. This work forms the
scientific basis for the joint state-federal management of eastern Bering
Sea and Aleutian Island crab stocks under the terms of a NPFMC fishery
management plan (FMP). Results have been promulgated through dissemination
of charts and tables, as well as ADF&G news releases. Results have been
reviewed by the NPFMC’s crab plan team and compiled into the annual Stock
Assessment and Fishery Evaluation (SAFE) report, which will be presented
to the Council during their October meeting. Results will soon be incorporated
in the Report to Industry on the 2002 Eastern Bering Sea Trawl Survey.
Numbers presented are trawl survey indices of population level and do
not necessarily represent absolute abundance. Results are as follows:
Red king crab (Paralithodes camtschaticus) Bristol Bay.
Legal males: 9.5 million crabs; 8% increase.
Prerecruits: 10.1 million crabs; 138% increase.
Large females: 19.0 million crabs; 11% decrease.
Synopsis: Abundance of most male size groups essentially doubled, perhaps indicating that the
2001 estimate was somewhat low. Mature females show little change. High
numbers of sublegal male crabs indicate good recruitment for future fisheries.
All new-shell females carried new eggs. Reproductive population estimates
are well above the minimum stock size threshold (MSST); the stock is not
considered to be in the overfished level of abundance.
GHL: 9.3 million lb (4,218 metric tons (t)). Fishery opens 15 October 2002.
Red king crab (Paralithodes camtschaticus) Pribilof District.
Legal males: 1.8 million crabs; no change.
Prerecruits: 0.02 million crabs; 99% decrease.
Large females: 0.44 million crabs; 89% decrease.
Outlook: Crabs are highly concentrated, and index has very low precision.
Females are poorly estimated. Reproductive population estimates are above
the MSST; the stock is not considered to be in the overfished level of
abundance. No recruitment is apparent. Red king crabs in the Pribilof
Islands region are usually harvested along with blue king crabs and are
currently the dominant species. There is concern that unacceptable levels
of blue king crab incidental catch could occur in a red king crab fishery.
GHL: Fishery will not open in 2002.
Pribilof Islands blue king crab (P. platypus) Pribilof District.
Legal males: 0.2 million crabs; 50% decrease.
Prerecruits: 0.02 million crabs; 84% decrease.
Large females: 1.2 million crabs; 23% decrease.
Outlook: Population is low, and trends are not easily detectable. Little
or no recruitment is apparent. Reproductive population estimate fell below
the MSST in 2002, and the stock is now considered to be in the overfished level of abundance.
GHL: Fishery will not open in 2002.
St. Matthew blue king crab (P. platypus) Northern District.
Legal males: 0.6 million crabs; 39% decrease.
Prerecruits: 0.2 million crabs; 62% decrease.
Large females: Not well estimated.
Outlook: Population has declined steeply since 1998. Abundance estimates
are affected by the portion of the stock occupying untrawlable grounds.
Reproductive population estimate continues to be below the MSST in 2002,
and the stock is considered to be in the overfished level of abundance.
GHL: Fishery will not open in 2002.
Tanner crab (Chionoecetes bairdi) Eastern District.
Legal males: 6.9 million crabs; 5% decrease.
Prerecruits: 15.1 million crabs; 13% decrease.
Large females: 11.3 million crabs; 14% decrease.
Outlook: Population is decreasing slightly due to continued low recruitment.
Reproductive population estimate continues to be below the MSST in 2002,
and the stock is considered to be in the overfished level of abundance.
GHL: Fishery will not open in 2002.
Snow crab (C. opilio) All districts combined.
Large males: 76.1 million crabs; 2% decrease.
Prerecruits: 248.0 million crabs; 12% decrease.
Large females: 500.7 million crabs; 67% decrease.
Outlook: Apparent recruitment that led to increased biomass in each of
the past 2 years has dissipated. Precipitous decrease in large female
abundance may reflect the uncertainty of recent estimates as well since
estimates have been dominated by a small number of tows. Lack of recruitment
to female reproductive stock is evidenced by the increasing prevalence
of old-shelled crab. Number of small males and females is also declining.
Reproductive population estimate that slightly exceeded MSST in 2001 is
below the MSST in 2002, and the stock is considered to be in the overfished
level of abundance but is above 50% MSST. Under the current rebuilding
plan and harvest strategy the fishery would be closed if the stock fell below 50% MSST.
GHL: 27.3 million lb (12,381 t). Fishery is currently scheduled to open 15 January 2003.
Hair crab (Erimacrus isenbeckii)
Large males: 4.2 million crabs; 81% increase.
Large females: Not well estimated.
Outlook: Population has been declining for several years but recruitment trends are unclear.
GHL: 236,368 lb (107 t). The fishery in the Northern
District of the Bering Sea will open 10 days following the closure of the
Bristol Bay red king crab fishery. The Pribilof District and Bristol Bay
portion of Registration Area J will not open in 2002.
Snow Crab Research
Research is under way under the recently established ADF&G/NMFS (AFSC)
snow crab Memorandum of Understanding (MOU). The first field research
collections for this research were completed in August 2002. September
collections are under way aboard the chartered fishing vessel Fierce Allegiance
as of this writing. This joint research project has three goals: 1) provide
quantitative measures of the EBS snow crab stock reproductive potential
and the means to better assess impacts to that potential due to harvest
of males; 2) specify the seasonality of the Bering Sea snow crab female
reproductive cycle; and 3) specify the seasonality of male molting and
testing the terminal-molt hypothesis for morpho-metrically mature male
snow crab under natural conditions in the Bering Sea. Collections will
be made in two specifically chosen study areas every 2 months over the next year.
This project is the first year-round study of EBS snow crab reproduction.
Results are intended to provide quantitative measures of the stock’s reproductive
potential and the means to better assess impacts to that potential due
to harvest of males. Snow crabs are jointly managed by the ADF&G and NMFS
according to the FMP for king and Tanner crabs in the eastern Bering Sea
and Aleutian Islands pursuant to the Magnuson-Stevens Fisheries Conservation
and Management Act. Snow crab fisheries in the EBS have recently have
been among the Nation’s most valuable fisheries but are subject to extreme
variation in recruitment.
By Robert Otto.
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