Abstract
Chinese fish farming is the oldest aquaculture in the word. The present pressure on the wild ichthyofauna and its diversity is threatening aquaculture because potential genitors are often caught in the wild. One of the possible responses to this threat is to provide new natural fish taxa for aquaculture. The objective of this study was to analyse the genetic structure of populations of Opsariichthys bidens and to describe its subdivisions, if any, using nuclear markers, to serve as a guideline for stock selection and management in the potential aquaculture of this species. In 2002 and 2003, two collecting trips were made, one in the middle Chang Jiang basin in Hunan Province, and another in the Xi Jiang basin in Guangxi Province, China. Length polymorphisms of the intron amplification (EPIC-PCR) were analysed on 24 systems, only five of which gave easily interpretable and polymorphic patterns, corresponding to 11 presumptive loci. According to the multidimensional statistics, the genetic analysis demonstrated the existence of four clearly independent geographical taxa included in O. bidens, characterized by unambiguous diagnostic intron loci. The distribution of these taxa confirms a similarity between both catchment populations: the middle Chang Jiang and the Xi Jiang samples of the Zhu Jiang basin. An additional output of the study was the choice of the population of each group to be first tested in Chinese fish farms. (c) 2006 The Linnean Society of London.