BIOCHEMICAL GENETIC POPULATION STRUCTURE OF 



YELLOWFIN SOLE, LIMANDA ASPERA, OF 



THE NORTH PACIFIC OCEAN AND BERING SEA 



W. Stewart Grant, 1 Richard Bakkala, 2 Fred M Utter, 2 David J. Teel, 2 and 



TOKIMASA KOBAYASHI 3 



ABSTRACT 



The gene products of 31 protein-coding loci were examined electrophoretically in samples of yellowfin sole 

 from the North Pacific Ocean and Bering Sea to assess genetic population structure. Four loci, Ada-2, Gpi-1, 

 Pep-2, and Pgd, were polymorphic where the frequency of the most common allele was <0.95 and were used 

 to test for allele-frequency differences within and between stock areas defined by life history and tagging 

 data. A nested contingency-table analysis of allelic frequencies showed that there were no genetic sub- 

 divisions either within the eastern Bering Sea or within the Gulf of Alaska. At the next higher nested level, 

 genetic heterogeneity was detected for the Japan-Bering Sea comparison at two loci and for the Japan- 

 Bering Sea-Gulf of Alaska comparison at four loci. Genetic distances between pairs of samples within each of 

 the genetic units averaged 0.0005 (±0.0003), but averaged 0.0049 (±0.0026) between samples from these 

 groups. The results of a gene-diversity analysis showed that 95.77c of the total genetic variation was con- 

 tained on average within populations and that 3.67c was due to differences between Japanese, Bering Sea, 

 and Gulf of Alaska fish. The remaining 0.77c of the genetic diversity was due to differences between pop- 

 ulations within these groups. The genetic differences between Bering Sea and Gulf of Alaska fish are due pro- 

 bably to genetic isolation and divergence caused by coastal glaciation in the Pleistocene Period. 



Population genetic data of four additional flatfishes are summarized in the form of a gene-diversity analysis 

 and compared with the genetic structure of yellowfin sole populations. There is generally very little genetic 

 differentiation among flatfish populations separated by < 1,000 km. The potential for mixing over this dis- 

 tance is great because of adult migration and passive drift of pelagic eggs and larvae. 



Yellowfin sole, Limanda aspera, can be found from 

 Vancouver Island in the eastern North Pacific Ocean 

 to Japan in the western North Pacific Ocean. 

 However, the greatest densities are found in the east- 

 ern Bering Sea where it is one of the major demersal 

 fishery resources. In the late 1950's and early 1960's 

 it was the primary target of Japanese and Soviet 

 distant-water fisheries. During the period 1959-62, 

 total catches ranged from 185,000 to 554,000 metric 

 tons (t) annually (Wakabayashi et al. 4 ) but have since 

 declined to range from 42,000 to 167,000 t. In 1975 

 the biomass of yellowfin sole was estimated to be 



'Northwest and Alaska Fisheries Center, National Marine Fish- 

 eries Service, NOAA, Seattle, Wash.; present address: Department 

 of Zoology, University of Cape Town, Rondebosch 7700, R. 

 South Africa. 



2 Northwest and Alaska Fisheries Center, National Marine Fish- 

 eries Service, NOAA, 2725 Montlake Blvd. East, Seattle, WA 

 98112. 



'Northwest and Alaska Fisheries Center, National Marine Fish- 

 eries Service, NOAA, Seattle Wash.; visiting scientist: Hokkaido 

 Regional Fisheries Research Laboratory, Fisheries Agency, 

 Kushiro, Hokkaido 085, Japan. 



4 Wakabayashi, K., R. Bakkala, and L. Low, 1977. Status of the 

 yellowfin sole resource in the eastern Bering Sea through 1976. Un- 

 publ. manuscr., 21 p. Northwest and Alaska Fisheries Center, 

 National Marine Fisheries Service, NOAA, 2725 Montlake Blvd. 

 East. Seattle, WA 98112. 



23% (1,000,000 t) of all demersal fishes sampled by 

 trawl survey covering the continental shelf region of 

 the eastern Berin Sea (Pereyra et aL 5 ). 



Yellowfin sole migrate from wintering areas on the 

 outer continental shelf to shallow water of the inner 

 shelf in summer where they feed and spawn. There 

 are two major winter concentrations in the eastern 

 Bering Sea (Fadeev 1970; Wakabayashi 6 ); the largest 

 is located in the vicinity of Unimak Island and the 

 second largest west of St. Paul Island. Other smaller 

 wintering concentrations have been recognized by 

 Fadeev (1970) and by Wakabayashi et al. (footnote 

 4), but the results of tagging studies (Wakabayashi et 

 al. footnote 4) indicate that these concentrations are 

 part of the Unimak Island group. 



Tagging studies by Japan indicated that the west 

 St. Paul Island and Unimak Island groups tended to 



Manuscript accepted March 1983. 



FISHERY BULLETIN: VOL. 81. NO. 4, 1983. 



'Pereyra, W. T., J. E. Reeves, and R. G. Bakkala. 1976. Demersal 

 fish and shellfish resources of the eastern Bering Sea in the baseline 

 year 1975. Processed rep., 619 p. Northwest and Alaska Fisheries 

 Center, National Marine Fisheries Service, NOAA, 2725 Montlake 

 Blvd. East, Seattle, WA 98112. 



'Wakabayashi, K. 1974. Studies on resources of the yellowfin 

 sole in eastern Bering Sea. I. Biological characters. Unpubl. 

 manuscr., 77 p. Japan Fishery Agency, Far Seas Fisheries Research 

 Laboratory, 5-7-1 Orido, Shimizu, Shizuoka, Japan. 



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