Upwelling and eddies affect connectivity among local populations of the goldeye rockfish, Sebastes thompsoni (Pisces, Scorpaenoidei)

The goldeye rockfish, Sebastes thompsoni, commercial rockfish catch in the Northwest Pacific Ocean, may influence its population structure. To clarify the population genetic structure of Korean S. thompsoni and its degree of hybridization with the most close species, Sebastes joyneri, we analyzed a mitochondrial (mt) DNA control region and eleven polymorphic microsatellite (ms) loci. S. joyneri individuals were clearly distinguished from S. thompsoni by the mtDNA control region and ms loci results, with single interspecific hybridization between two species suggesting no impact on genetic structure of S. thompsoni. Analysis of mtDNA revealed no population structure within S. thompsoni, suggesting the survival of a single population in southern refugia during the glacial period. The ms loci results, in contrast, showed two genetically distinct clusters within S. thompsoni: One was predominant throughout Korean coasts (from the Yellow Sea, via the Korea Strait to the East Sea); the other was predominant at Dokdo Island in the East Sea; and both occurred in similar ratios at Wangdolcho Reef in the East Sea. A possible factor that restricts gene flow between Korean coastal and offshore populations in the East Sea may be related to the complex oceanic current patterns such as eddies and upwelling, which represent impermeable barriers to population connectivity for this species. Our findings highlight that these two populations might be representative of two separate stock within Korean waters and maintain their geographically related genetic structure.