Comprehensive assessment of population genetic structure of the overexploited Japanese grenadier anchovy (Coilia nasus): Implications for fisheries management and conservation

Japanese grenadier anchovy, Coilia nasus, is a commercially important fish species in China. Three ecotypes (anadromous, landlocked and freshwater-resident populations) are distributed across its range. Due to anthropogenic activities such as overfishing and habitat deterioration, the stock status of this species has sharply declined. Clarifying population genetic structure and genetic relationships among ecotypes is essential for the conservation and stock management of C. nasus. Using 18 microsatellite loci, the distribution of genetic variation among 18 geographic populations (nine anadromous populations, four landlocked populations, and five freshwater-resident populations) was examined. High levels of genetic diversity were observed in all populations. Significant genetic differentiation among populations was detected and four genetic groups were identified, which might arise from current geographic segregation, different life-history strategy, and historical geographical factors. High assignment accuracies ( >= 85%) accessed for all populations suggested microsatellite loci can be used as an effective tool for discriminating the origin of individuals. Our study provided valuable information for conservation and sustainable management of C. nasus across its entire distribution range, and demonstrated the utility of microsatellite data to inform conservation units in highly exploited species.