Genetic diversity, effective population size, and population structure of mandarin fish (Siniperca scherzeri) in Korea: Implications for broodstock management and hatchery seed production

Genetic evaluation of hatchery resources is essential for the stable production of high-quality seed in freshwater aquaculture, particularly in species for which artificial propagation and release are being developed or expanded. In this study, we assessed the genetic diversity, effective population size, and population structure of Korean mandarin fish, Siniperca scherzeri, in Korea using 15 microsatellite loci from 304 individuals representing 14 populations, including 11 wild populations, one broodstock population, and two hatchery-produced seed groups intended for release. Genetic diversity varied among populations, with the mean number of alleles ranging from 4.13 to 7.00, observed heterozygosity from 0.527 to 0.710, and expected heterozygosity from 0.589 to 0.706. Significant deviations from Hardy-Weinberg equilibrium were detected in most populations, and the highest inbreeding coefficient was observed in SF_SJ (F IS = 0.191). Effective population size (N e ) estimates differed markedly among populations, with especially low values in SC (N e = 5), SF_SJ (N e = 12), BR_L (N e = 25), and BrStock (N e = 30). Pairwise F ST , Bayesian clustering, and discriminant analysis consistently revealed clear but heterogeneous population structuring, with SC showing the strongest genetic differentiation and high self-assignment. Recent migration analysis also indicated asymmetric contemporary gene flow among several population pairs, whereas SC showed no migration rate above the 3% visualization threshold. These results demonstrate substantial genetic differences among candidate broodstock and two hatchery-produced seed groups intended for release of S. scherzeri, indicating that their suitability as hatchery broodstock sources is not equivalent. The present study therefore provides a genetic basis for broodstock selection, more even parental representation, and genetically informed mating design to support stable hatchery seed production in S. scherzeri.