基于年龄结构的中华鲟资源量估算方法

根据长江中的中华鲟亲鱼捕捞数据的年龄结构,推算不同年龄段中华鲟亲鱼进入长江参与繁殖的占比,首次将长江和海洋中的中华鲟同时纳入估算模型进行计算,构建了一套估算中华鲟资源量的新方法。稳态计算结果显示,在葛洲坝截流前,长江中每年有效补充量为1 882尾,长江和海洋中育龄(雌:13~34龄,雄:8~27龄)总资源量为32 260尾,其中雄鱼15 310尾,雌鱼16 950尾,每年在长江中参与繁殖的中华鲟新老股群之和(1 727尾)占总资源量的比例约5%。计算得出葛洲坝截流后长江中的中华鲟产卵繁殖容量仅为截流前的6.5%,1981年葛洲坝截留造成68%~80%的1980年老股群被阻隔在上游。结合葛洲坝截流后的捕捞数据推算了1981年后长江和海洋中的中华鲟资源量变迁过程。计算结果与捕捞数据反映的趋势一致,证明模型可靠有效。研究表明,葛洲坝截流后,随着捕捞量的减少,长江中的繁殖群体数量上升,1990年左右达到峰值(约2 200尾),随后迅速下降,2010年为170尾左右。葛洲坝截流后中华鲟产卵繁殖环境容量的大幅下降是近年来中华鲟资源量急剧下降的重要原因。

An age-structured population model of the Chinese sturgeon(Aciperser sinensis)

The estimation of the abundance of Chinese sturgeon, Acipenser sinensis, is of great significance to its conservation and the assessment of the ecological impact of hydropower construction. Based on its age-structure of the historical fishing data in the Yangtze River, we calculated the age-specific proportion of the adults, and then constructed an age-structured population model to estimate the abundance dynamics of A. sinensis, including the population sizes in the Yangtze River and the sea. Under the steady-state condition (prior to the Gezhouba river closure), we calculated that the amount of effective recruitment was 1 882 individuals every year, and the total number of the adult A. sinensis (female:13-34 year old, male:8-27 year old) was 32 260 individuals, with 15 310 of the male and 16 950 of the female. The numbers of adults in the Yangtze River (1 727 individuals) was 5% of the total in the Yangtze River and the sea. Using the sex ratio and old cohort proportion of historical fishing data, we estimated that the remnant spawning capacity of A. sinensis was only 6.5% after the river closure of the Gezhouba Dam, and 68%-80% of the old cohort was obstructed by Gezhouba Dam in the upper river. Then we estimated the dynamics of A. sinensis in the Yangtze River or/and the sea after 1981. The results show that after the river closure of Gezhouba Dam, the number of spawners in Yangtze River increased with the decrease of harvest number, and reached its peak in 1990 (about 2 200), then decreased rapidly, and was about 170 in 2010. The reduction of the spawning ground environmental capacity after the river closure of Gezhouba Dam was one of the reasons for the sharp decline of population size of A. sinensis.