[Population resources and fishery management policies of Schizopygopsis younghusbandi in the Yarlung Zangbo River, China.].

Schizopygopsis younghusbandi, an endemic species in China, is threatened by overfi-shing and biological invasion. With 694 individuals collected during August 2008 to August 2009 from the Xietongmen to Nimu of Yarlung Zangbo River, Tibet, the population resources and fishery management policies of the fish were studied using per-recruit models. The total instantaneous annual mortality (Z) of S. younghusbandi was 0.81 year for females and 0.78 year for males. The range of natural mortality (M) of females and males were 0.17-0.27 year and 0.21-0.33 year, respectively. The range of current fishing mortality (F) was 0.54-0.64 year for females and 0.45-0.57 year for males. The range of spawning potential ratio of S. younghusbandi was 10.1%-17.9% for females, being significantly lower than the threshold reference point (F). That for males was 28.3%-43.6%, with 22.3% of which was higher than the target reference point (F). This result indicated that the stock of S. younghusbandi had been over-exploited under the current fishery management policy. To evaluate the protective effects of capture age and seasonal closure, 14 different fishery management policies were simulated. The results showed that the stock of S. younghusbandi would be effectively conserved by enhancing the capture age to not less than 10 years old or setting the seasonal closure from February to June.