Comparative genetic variability between broodstock and offspring populations of Korean starry flounder used for stock enhancement in a hatchery by using microsatellite DNA analyses.

Korean starry flounder, Platichthys stellatus (Pleuronectidae), is one of the most economically important fishery resources in Korea. We investigated the effect of current artificial reproduction in a hatchery facility, genetic divergence between the broodstock and their offspring populations of starry flounder in a hatchery strain to be stocked into natural sea areas was accessed using 9 polymorphic nuclear microsatellite DNA loci. High levels of polymorphism were observed between the 2 populations. A total of 96 alleles were detected at the loci, with some alleles being unique in the broodstock. Allelic variability ranged from 8 to 17 in the broodstock and from 7 to 12 in the offspring population. Average observed and expected heterozygosities were estimated at 0.565 and 0.741 in the broodstock samples and 0.629 and 0.698 in the offspring population, respectively. Although no statistically significant reductions were found in heterozygosity or allelic diversity in the offspring population, a considerable loss of rare alleles was observed in the offspring population compared with that in the broodstock. Significant genetic difference was detected between the broodstock and offspring populations (FST = 0.021, P < 0.05). These results suggest that more intensive breeding practices for stock enhancement might have resulted in a further decrease of genetic diversity. Thus, genetic variations of broodstock and progeny should ideally be monitored in both breeding and release programs as a routine hatchery operation in order to improve the starry flounder hatchery management. This information might be useful for fishery management and aquaculture industry of P. stellatus.

Microsatellite analysis as a tool for discriminating an interfamily hybrid between olive flounder and starry flounder.

An interspecific artificial hybrid was produced between two economically important aquaculture flatfish: olive flounder (Paralichthys olivaceus) and starry flounder (P. stellatus). This hybrid displays the rapid growth characteristic of the former and tolerance to low temperatures and low salinity of the latter, but the genetics of inheritance in this hybrid have not been elucidated. Polymorphic microsatellite markers developed for P. olivaceus and P. stellatus were tested to determine if these markers can be used for analysis of parentage and genetic inheritance. Multiplex PCR using two primer sets that were specific to each species produced PCR products of different sizes; these could be used for the identification of interspecific hybrids. Among the 192 primers derived from olive flounder, 25.5% of the primer sets successfully amplified genomic DNA from starry flounder, and 23% of the 56 primer sets originating from starry flounder amplified DNA from olive flounder. Analysis of genetic inheritance in the hybrid using seven of the 62 microsatellite markers common to both species demonstrated classic Mendelian inheritance of these markers in the hybrid progeny, with the exception of one locus identified as a null allele in the hybrid. These results demonstrate that cross-specific microsatellite markers can be used tools for parentage analysis of hybrid flatfish, for mapping quantitative trait loci, for marker-assisted selective breeding, and for studies of the evolution of fish.