Circumpolar genetic population structure of polar cod, Boreogadus saida

Polar cod, Boreogadus saida, is an important part of Arctic and boreal marine ecosystems. Knowledge of polar cod population genetic structuring can provide insight into how the species may respond to environmental change, and allow for establishment of meaningful management units. To examine population genetic structure of B. saida, we analysed nine microsatellite DNA loci in 2269 fish collected at 19 locations across the species’ range. Genetic differentiation was detected (FST = 0.01, p < 0.01), which had concordance with geography. A Canada East group consisted of fish collected from Resolute Bay to the Gulf of St. Lawrence. Three additional groups were observed. These consisted of a Canada West group containing specimens from the Canadian Beaufort Sea and Amundsen Gulf, a Europe group containing specimens from the Greenland Sea, Iceland and the Laptev Sea, and a US group consisting of specimens collected in the North Bering, Chukchi and Western Beaufort seas. Very little genetic differentiation was detected within the identified groups. Physical distance, geophysical structure and oceanography all appeared to have the potential to influence levels of genetic divergence. The population genetic structure detected is likely to be important for the response of B. saida to environmental change, and should be considered in management of human activities that may impact this foundational species.