Relationship between genetic risk and stock enhancement of the silver carp (Hypophthalmichthys molitrix) in the Yangtze River

Abstract

Hatchery release of silver carp (Hypophthalmichthys molitrix) is an efficient strategy that has been carried out for years, and its scales expand year by year in the lower reaches of the Yangtze River (LRYR) in China. As the cultured juveniles are released into self-recruiting wild population to increase fisheries resources yields, they may potentially come along with negative impacts such as intra-inter specific completion, loss of genetic diversity and fitness, even causing genetic risk. To assess the relationship between genetic risk and stock enhancement (SE) of the silver carp in the Yangtze River (YR); microsatellite loci amplification, parentage assignment, genetic diversity, genetic differentiation and structure were conducted and testified by the help of eleven fluorescence-labeled microsatellite markers method. Results showed that silver carp populations in the YR had relatively higher genetic diversity (UHe), inbreeding coefficient (Fis), and effective population size (Ne) than breeding stock populations from eight hatcheries. By using the analysis of molecular variance (AMOVA), results showed that the percentage of variance among populations and within populations were 4.15 % and 95.85 %, respectively, which indicated that genetic structure of YR populations possibly had been changed by SE. Therefore, the present study suggests that the large-scale SE possibly resulted in negative genetic impact on silver carp population. Most importantly, an evaluation system in fisheries resource recruitment and genetic risks was established for SE and management.