Genetic diversity and reproductive success of a wild population of Chinese sturgeon (Acipenser sinensis) from the Yangtze River inferred from juveniles born in 2014

The Chinese sturgeon (Acipenser sinensis Gray, 1835) is a large anadromous fish species, which is under considerable threat due to dramatic declines in population numbers. In the current study, population genetic diversity and individual reproductive success were assessed using nuclear microsatellite markers (simple sequence repeat, SSR) and complete mitochondrial (mtDNA) genome analysis of juveniles born in 2014. Results showed the existence of size polymorphism in the mtDNA genome of Chinese sturgeon, which was caused by a repeat motif. Population genetic diversity was high based on both SSR (Ho: 0.728±0.211; He: 0.779±0.122) and mtDNA genome analyses (H: 0.876±0.0035; Pi: 0.0011±0.0010). A positive inbreeding coefficient (FIS: 0.066±0.143) was also found, indicating the occurrence of inbreeding. Reconstruction of sibling groups identified 11 mothers and 11 fathers involved in reproduction of Chinese sturgeons in 2014. Variance in individual reproductive success was not significant, with reproductive success of parent fish instead shown to be relatively even (P=0.997>0.05), thus suggesting the absence of sweepstakes reproductive success (SRS). These results indicate that, in regard to conservation, loss of genetic diversity due to the effects of SRS is not of particular concern. However, we must focus on having an adequate number of adults and suitable environmental conditions to ensure that fish can reproduce.