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2009 Lowell Wakefield Fisheries Symposium

The 25th Lowell Wakefield Fisheries Symposium entitled Biology and Management of Exploited Crab Populations under Climate Change took place in Anchorage, Alaska, 10-13 March 2009. The approximately 80 participants comprised crab biologists and managers from the United States, Canada, Greenland, Japan, Norway, and Australia. The symposium consisted of six sessions covering the following topics: 1) abundance and distribution; 2) measurement of disease and effects of environmental stressors; 3) reproduction and size at maturity; 4) life history, habitat use, and predation; 5) stock- and environment-recruitment relationships; and 6) stock enhancement and culture. Many of these session topics have been the focus of the Shellfish Assement Program at the Kodiak Laboratory (KL), so the laboratory actively participated at the symposium with KL personnel taking the lead on seven presentations and posters and also being coauthors on an additional five presentations and posters. Eight publications are pending as a result of the symposium (Table 1).

see caption
Figure 11. Biomass of Chionoecetes (C.) and Lithodes (L.) species encountered on the eastern Bering Sea slope survey, 2002, 2004 and 2008. (A) Biomass by year; all depths combined, (B) biomass by depth; years 2002, 2004 and 2008 combined.

Crab abundance and distribution in the eastern Bering Sea (EBS) is one focus of the shellfish survey and assessment group. Surveys of crab abundance and distribution have occurred for decades although time series data for the early Bering Sea surveys are not well developed. Malley and Foy presented efforts to rescue and retrieve historic Bering Sea crab data. Over 71,000 records from 1966-74 surveys that include embedded environmental data have been scanned, archived, and entered into a searchable database. The relational database will serve research and modeling efforts concerning population dynamics, fishery management, and ecology. Although most of the focus historically has been on the EBS shelf, crabs on the continental slope have been assessed periodically.

Haaga et al. examined the abundance and bathymetric distribution of these largely unstudied crabs along the slope and found that Chionoecetes sp. biomass showed a downward trend from 2002 to 2008, while Lithodes sp. increased during the same period. (Fig. 11a). The majority of C. bairdi and C. opilio occurred at depths of 200-400 m and C. tanneri were found at 400-1,000 m. Biomass for L. aequispina decreased with depth, while L. couesi biomass increased from 600-1,200 m. Overall, the largest biomass encountered along the slope was C. angulatus, with the largest numbers found below 800 m. (Fig. 11b). Although the commercially important species of C. bairdi and C. opilio utilize the Bering Sea slope areas, it appears that the total biomass is small and they are located in areas that are likely not well suited to commercial fishing.

Researchers with the Shellfish Assessment Program have conducted many studies to understand the complex reproductive dynamics of numerous crab species with the ultimate goal of using this information to improve crab management. In recent years, the program has been collaborating with Alaska Department of Fish and Game (ADF&G) and the University of Alaska Fairbanks (UAF) studying egg production of Bristol Bay red king crabs (Paralithodes camtschaticus) for the development of biological reference points.

Table 1.  Kodiak Laboratory publications pending for inclusion in the 25th Lowell Wakefield Fisheries Symposium: Biology and Management of Exploited Crab Populations under Climate Change symposium proceedings.
Authors Title
E. A. Chilton, C. E. Armistead, and R. J. Foy Reproductive timing of Bristol Bay red king crab and the cold pool intrusion
K. M. Swiney, J. B. Webb, G. H. Bishop, and G. L. Eckert Variability and measurement of Alaska red king crab fecundity
S. L. Persselin and B. Daly Assessment of diet and water source on cultivation of red king crab (Paralithodes camtschaticus) larvae
D. Urban Seasonal predation of Pacific cod on Tanner crab in Marmot Bay, Alaska
S. B. Van Sant, F. Tapella, and C. Romero Effects of temperature and rearing density in golden king crab (Lithodes aequispinus) larval cultivation
C. L. Worton, D. Urban, K. M. Swiney, Z. Grauvogel, and S. Byersdorfer Is the commercial size limit of Dungeness crabs in Alaska appropriate based on their size at physiological and functional maturity?
M. S. M. Siddeek, L. Rugolo, J. Zheng, and J. Turnock The new precautionary control rules for Bering Sea and Aleutian Islands crab fisheries management
J. Zheng, D. Pengilly, R. J. Foy, and D. Barnard Stock assessment model evaluation for St. Matthew blue king crab



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