Genetic Analysis Reveals Restricted Dispersal of Northern Rockfish along the Continental Margin of the Bering Sea and Aleutian Islands

The effective conservation and management of a species require knowledge of its population structure and life history. Fish that are mobile, long-lived, and abundant and that have pelagic larvae are often presumed to disperse over large geographic areas. However, if the individuals of such a species have limited dispersal, spatial scale must be considered when developing management plans. The economically and ecologically important northern rockfish Sebastes polyspinis, which is most abundant along the continental margin of the Aleutian Islands, has the potential to disperse widely during its life. The population genetic structure of a species provides a window into its demographic structure. Consequently, the variation at 11 microsatellite loci was used to characterize the geographic structure and connectivity of northern rockfish collected in 2004 along the continental margin of the Bering Sea slope and the Aleutian Islands. Significant genetic structure (F-ST = 0.0017) was detected, and a significant isolation-by-distance relationship indicated that there is limited lifetime dispersal (on the order of 100-200 km), which is much smaller than the scales used for sampling and management. In addition, the genetic divergence along the area sampled suggests decreased gene flow at Amchitka Pass and between the eastern Bering Sea and eastern Aleutian Islands.