Comparative genetic diversity of wild and hatchery-produced populations of tongue sole (Cynoglossus semilaevis) using multiplex PCR assays with polymorphic microsatellite markers.

The tongue sole, Cynoglossus semilaevis (Cynoglossidae), is one of the most economically important fishery resources in Korea. This study presents a preliminary investigation of the future viability of the complete aquaculture of tongue sole in Korea. Specifically, possible differences in genetic variability between wild populations of tongue sole from Korea and hatchery-produced populations of tongue sole from China were assessed using multiplex assays with 12 polymorphic nuclear microsatellite DNA loci. High levels of polymorphism were observed between the 2 populations. A total of 135 different alleles were found, varying from 5-15 alleles per locus, with some alleles being unique. These findings indicate a high level of genetic variability in both the wild and hatchery-produced populations. Although a considerable loss of rare alleles was observed in hatchery samples, there were no statistically significant reductions of heterozygosity or allelic diversity in the hatchery population compared to the wild population. Moreover, the inbreeding coefficient was very low (FIS = -0.010-0.052) for both populations. However, significant genetic heterogeneity was found between the 2 populations. These findings indicate that genetic drift has likely promoted differentiation between these 2 populations, and might have negative effects on the reproductive capacity of the stock, because genetic factors are important in the production of high quality seed for complete aquaculture. Therefore, aquaculture management should incorporate basic genetic principles into existing molecular monitoring protocols. The information compiled by this study is anticipated to provide a useful genetic basis for future complete culturing plans and management of C. semilaevis in fisheries.