长江上游龙溪河厚颌鲂种群资源的利用现状和保护

Exploitation Status and Conservation of a Population of Megalobrama pellegrini in Longxi River in the Upper Yangtze River Basin

由于栖息地被破坏和过度捕捞等人为因素的影响,长江上游特有鱼类厚颌鲂M egalobrama pellegrini的种群资源显著减少。利用单位补充量模型进行分析,结果显示:长江上游支流龙溪河的厚颌鲂种群资源已经被过度开发,现有的捕捞强度(0.94年-1)远超过种群可承受的水平(F40%=0.18年-1,F0.1=0.20年-1和F25%=0.30年-1);繁殖潜力比为4.50%,低于25%,将造成种群的补充量不足,导致种群资源量下降;限制捕捞强度和捕捞规格是控制过度捕捞、保护种群资源的有效措施。

Megalobrama pellegrini is an endemic fish in the upper reaches of the Yangtze River. Populations of this species have been depleted recently due to overfishing and environmental deterioration resulting from damming. In this study, yield per recruit and spawning stock biomass per recruit models were employed to assess the exploitation status of the stock in the Longxi River, a tributary of the upper Yangtze, and determine the conservation strategies. The results indicated that the stock had been overfished far beyond the ideal target reference points F40% （0. 18 year^-1）, F01 （0.20 year^-1） and threshold reference point F25% （0.30 year^-1）. The percentage of spawning stock biomass per recruit of the current fishing level to that of the no fishing level was estimated to be merely 4.50% , possibly leading to high risk of the recruitment failure in the future. In order to maintain the population, conservation strategies were discussed based on yield per recruit and spawning potential ratio curves. The results based on natural mortality rates suggested to set a minimum catch size and to limit the catches by establishing quotas of annual captures. This would probably permit sustaining the population and reduce local risk of extinction.