Increased fishing effort in the international waters of the Aleutian Basin has focused much interest on defining the stock structure of walleye pollock, Theragra chalcogramma, in the Bering Sea. Variation in mitochondrial DNA (mtDNA) was examined via restriction endonuclease digestions in 168 walleye pollock from three areas in the eastern Bering Sea and from Shelikof Strait, Gulf of Alaska. Nine endonucleases produced variant restriction patterns both within and among populations. A total of 50 restriction sites were revealed along the mtDNA molecule. Two dominant genotypes were found in 39 and 21 individuals, respectively. Fifty-one genotypes (78% of the total) were represented by a single specimen. Clustering of genetic distances suggests the existence of several walleye pollock stocks in the Bering Sea and Gulf of Alaska. Genetic divergence among stocks may be related to the prevailing current patterns found in these areas.
Biogeographic Evidence for Selection on Mitochondrial DNA in North Pacific Walleye Pollock Theragra chalcogramma