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Identifying Red and Blue King Crab Stocks for Sustainable Harvest and Sustainable Coastal Alaskan Communities


David TallmonFisheries Division
School of Fisheries and Ocean Sciences, University of Alaska Fairbanks



Alaska waters support some of the world's largest concentrations of red and blue king crab, and commercial, subsistence, and sport fisheries for these species is an important part of many coastal community economies. In addition, multi-agency efforts are under way to develop the understanding and technology to hatchery-enhance depressed stocks of red and blue king crab in parts of the state. However, fishery managers lack an important management tool, an understanding of the genetic structure and mating structure of these important fisheries stocks. Research conducted to date has been inconsistent. In this study, researchers will continue a comprehensive analysis of the genetic and mating structure of Alaska's many stocks of red and blue king crab.


The issue

Successful management of marine species hinges upon accurate identification of the stocks. Despite the economic and subsistence importance, as well as iconic status, of king crab in Alaska, there is almost no published information about their geographic stock structure. Existing results are inconsistent. Without genetic data to delineate red king crab and blue king crab stock structure, harvest and enhancement strategies used to set harvest goals and ensure stock sustainability will be based largely upon conjecture and subject to uncertainty. With genetic data, managers can confidently identify where stock boundaries should be placed, and thus maximize the benefits of harvest and enhancement activities while minimizing negative impacts on long-term stock sustainability.

Why is this an Alaska Sea Grant project?

One of Alaska Sea Grant's six key goals outlined in the 2009–2013 Strategic Plan is sustained, well-managed, and healthy marine, coastal, and watershed ecosystems in Alaska. The program pursues this goal through support of research that provides decision-makers with science-based information that can be used to craft well-informed policies governing the use and conservation of Alaska's marine and coastal resources.

How will researchers conduct their study?

Researchers and collaborators will use microsatellite and mtDNA genotyping techniques to determine the population and mating structure of red king crab and blue king crab in Alaska. Genotyping methods will be applied to historic samples (1980s and 1990s) and current (2008) samples collected from the same locations throughout Alaska. This approach will allow the principal investigator and collaborators unprecedented insight into the stock structure of Alaska red and blue king crab stocks.

Research collaborators

Alaska King Crab Research, Rehabilitation and Biology Program (AKCRRAB)
NOAA Fisheries
Alaska Department of Fish and Game
Alutiiq Pride Shellfish Hatchery
Gulf of Alaska Coastal Communities Coalition (GOAC3)
United Fishermen’s Marketing Association, Inc.


What researchers learned

Blue king crab (Paralithodes platypus Brandt, 1850) has been an economically important species in Alaska since the 1970s, but its abundance has decreased substantially since the mid-1980s. Despite fisheries closures, abundances have not rebounded to previous levels. This failure has highlighted the dearth of information on the species and the need for research into genetic population structure and reproductive biology in order to better inform management efforts. Blue king crab tissue and hemolymph samples were collected from eight geographically distinct locations in Southeast Alaska, the Bering Sea, and Russia (n = 770). Allele frequencies at 10 polymorphic microsatellite loci were compared among collection locations. Moderate genetic differences were detected among all locations (overall FST = 0.027, SE = 0.005). Historical and current collections from St. Matthew Island and the Pribilof Islands contained samples temporally separated by approximately two generations. Heterogeneity was detected among temporal samples, and comparisons within each location suggested that allele frequencies had changed over time. Mating structure was examined by genotyping 20 progeny from each of 44 blue king crab broods collected from 3 different locations in the Bering Sea. All evidence supported single paternity for this species. This study suggests that Alaskan blue king crab stocks be managed at the population level, monitored for temporal genetic changes, and that potential future enhancement activities incorporate the single paternity mating system into determinations of broodstock composition and number.

Research impacts

With accurate stock structure data, sound and sustainable harvest quotas can be set for commercial, subsistence, and recreational fisheries, and benefits can be maximized to the coastal communities that depend upon these fisheries.

This project will provide peer-reviewed and published data to the Alaska Department of Fish and Game supporting an understanding of stock structure and mating structure, prior to approval of wild enhancement activities.

Research outcomes

This research will provide several important results for Alaska communities. Fisheries management agencies such as the Alaska Department of Fish and Game and NOAA Fisheries have adopted the stock concept for fisheries management. The stock concept is used to direct recreational, subsistence, and commercial harvest management and quotas. This study will provide the genetic data needed to determine the stock structure and geographic boundaries of red and blue king crab in Alaska waters.

Stoutamore, J.L. 2014. Population genetics and mating structure of blue king crab (Paralithodes platypus). Master's thesis, University of Alaska Fairbanks, SGT-14-01, 90 pp.

Vulstek, S.C., T.P. Linderoth, J.R. Guyon, and D.A. Tallmon. 2013. Spatio-temporal population genetic structure and mating system of red king crab (Paralithodes camtschaticus) in Alaska. Journal of Crustacean Biology 33(5):691–701. http://doi.org/10.1163/1937240X-00002173

Stoutamore, J.L., C.N. Love, S.L. Lance, K.L. Jones, and D.A. Tallmon. 2012. Development of polymorphic microsatellite markers for blue king crab (Paralithodes platypus). Conservation Genetics Resource 4(4):897–899. http://doi.org/10.1007/s12686-012-9668-8

Vulstek, S.C. 2011. Spatio-temporal population genetic structure and mating system of red king crab (Paralithodes camtschaticus) in Alaska. Master's thesis, University of Alaska Fairbanks, SGT-11-04, 45 pp.