Study on the genetic structure of wild and hatchery populations of Procypris rabaudi Tchang, an endemic fish in the upper Yangtze River

Abstract

The rock carp (Procypris rabaudi Tchang), an endemic fish in the upper Yangtze River, have declined in the wild under the intense human disturbance. The artificial propagation and release of rock carp has been developed in recent decades for restoration of stocks. In order to understand the effects of the release of hatchery reared fish on wild populations, this study investigated genetic diversity and structure among Wanzhou (the place to have the largest release of rock carp), Chishui, Hejiang wild populations and hatchery population (main source of Wanzhou released individuals) by microsatellite markers. The results revealed that wild populations and hatchery population contributed similarly to high level of genetic diversity. Population structure analysis suggested that genetic divergence reflected among Wanzhou and other wild populations occurred effected by released individuals. Information on the effective population sizes showed the current Wanzhou wild populations and hatchery population were not sufficient to sustain the long-term survival of rock carp. And there was a close relationship between Wanzhou wild populations and hatchery population containing a smaller number of broodstocks. The hatchery release in the Wanzhou area was found so far to have had little effect on its genetic diversity, and has contributed to a change of genetic structure in the wild population and has been facing the threat of inbreeding decline of this vulnerable fish species. It is suggested that new wild individuals should be added to the brood stock to enhance the genetic diversity of the hatchery population of this endangered fish.