Genetic structure in the marbled rockfish (Sebastiscus marmoratus) across most of the distribution in the northwestern Pacific

The marbled rockfish (Sebastiscus marmoratus) is an important species that is widely distributed across the marginal seas of the northwestern Pacific. Several kinds of DNA markers, such as amplified fragment length polymorphisms (AFLP), mitochondrial DNA (mtDNA) and single nucleotide polymorphisms (SNPs), have been used to assess the population genetic characteristics of this species in previous studies. However, there have been no genetic profiling studies to cover the entire distribution. Here, six highly polymorphic microsatellite markers were applied to 18 populations across a spatially large area (from the Sea of Japan in the north to the South China Sea in the south). The results showed that the whole population exhibits high, stable genetic diversity, low relatedness and large effective population size. There was very weak genetic differentiation overall and no isolation by distance occurred among the populations, which may be attributed to significant contemporary gene flow, each generation. The above results may lead us to infer that the recent S. marmoratus population structure could be considered as one large integrated population. The present study will be beneficial to population conservation and fisheries management of S. marmoratus and will lead to better insights into the genetic characteristics of other species that belong to the Sebastidae family.