Population genetics and mating structure of blue king crab (Paralithodes platypus)

Abstract

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 Fishery 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). Heterogeneity was detected among temporal samples collected at the Pribilof Islands and St. Matthew Island. Comparisons suggested allele frequencies within each location 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.