Genetics studies on king crab populations conducted in Juneau, Alaska

Egg clutch of crab broodstock. Photo by C. Stevens.

Professor David Tallmon (University of Alaska Southeast) and fisheries graduate student Scott Vulstek (University of Alaska Fairbanks, Juneau Center) are examining king crab population genetics. Understanding population genetics is critical for assessing consequences of potential out-planting in any enhancement project. The goals of the genetics research project on king crab are to determine (1) locations of genetically distinct crab populations in Alaska, (2) how much genetic exchange occurs among crab populations, (3) how many individuals contribute genetically to the populations, and (4) whether female red king crabs mate with more than one male per season (single vs. multiple paternity).

To understand the genetic structure of crab stocks, Tallmon and Vulstek, in collaboration with the Alaska Department of Fish and Game Gene Conservation Laboratory, are analyzing the DNA of red king crabs collected in 1988-1996 and 2008, from Norton Sound, Pribilof Islands, Bristol Bay, and Southeast Alaska. They are also looking at DNA from blue king crabs collected at Little Diomede and the Pribilof Islands. Thus far, red king crab broods from 12 females have been genotyped at four microsatellite loci (DNA segments) with no evidence of multiple paternity. Single paternity suggests that larger numbers of broodstock may be needed to achieve similar genetic diversity in offspring as would be present with multiple paternity. However, single paternity may make it easier to identify hatchery-reared individuals released in the wild. Tallmon and Vulstek will continue to reveal population structure as they identify and implement new microsatellite markers (simple, repeating DNA sequences).

Long-term genetic research aims to determine a genetic baseline of wild stocks, develop a genetic marker with full parental genotype, and further assess genetic risks of releasing hatchery-reared crabs. Acquiring this knowledge will aid policy-makers in deciding whether to pursue active rehabilitation of depressed wild king crab stocks through hatchery enhancement.

AKCRRAB is a research and enhancement project sponsored by the Alaska Sea Grant College Program, UAF School of Fisheries and Ocean Sciences, NOAA Fisheries, the Alutiiq Pride Shellfish Hatchery, community groups, and industry members. For more information go to http://seagrant.uaf.edu/research/projects/initiatives/king_crab/general.