Panmixia in Alaskan populations of the snow crab Chionoecetes opilio (Malacostraca: Decapoda) in the Bering, Chukchi, and Beaufort Seas

Decreasing sea ice in the Arctic is expected to impact marine ecosystems, and to lead to increased human activity in the form of shipping traffic, fishing pressure, and mineral resource exploration and extraction. In the face of these pressures, we examine genetic population structure in the snow crab Chionoecetes opilio (Fabricius, 1788), throughout its distribution in Alaskan waters, to determine degrees of population connectivity between the Arctic and more southerly portions of the species' range. Snow crabs are widely distributed on the high-latitude continental shelves of North America, where they support a valuable commercial fishery in the United States and Canada. Fishing pressure in United States waters is currently concentrated in the Bering Sea, but large populations of snow crab also occur farther north in the Chukchi and Beaufort Seas. These northern stocks are not well studied, and not yet targeted by fisheries, although commercial-sized individuals were recently reported in areas of the Western Beaufort Sea. We used seven polymorphic microsatellite markers to examine tissue samples from 573 individual crabs collected at 12 sampling locations distributed across the Bering, Chukchi, and Beaufort Seas. These data indicate that Alaskan snow crabs constitute one large, panmictic population. Connectivity between fishery areas in the south and unexploited regions farther north thus appears to be substantial, perhaps due to a lengthy larval dispersal period and highly mobile adult population.