长江上游宜昌鳅早期资源特征及影响因子分析

摘要

为探究长江上游鱼类早期资源在金沙江一期工程蓄水前后的变化情况,2011—2015年每年5月5日—7月10日在长江上游江津断面,通过定点连续采样监测对宜昌鳅早期资源进行了调查.结果显示,2011—2015年累计335 d的调查中,宜昌鳅(Gobiobotia filifer)鱼卵出现天数为135 d,共采集到鱼卵1492粒,估算出采样期间江津断面宜昌鳅鱼卵径流量分别为7.18×107粒、5.54×107粒、2.62×107粒、9.85×107粒和14.11×107粒,是长江上游主要的产漂流性卵鱼类之一.通过Pearson Correlation对宜昌鳅鱼卵密度与水文环境因子进行相关性分析,结果表明宜昌鳅鱼卵日均密度与透明度存在极显著的正相关关系(P<0.01),与水位、 流量、 电导率、 流速则存在极显著的负相关关系(P<0.01).蓄水前后,宜昌鳅的早期资源量出现了较大的波动,相对多度则出现了明显的上升,由4.64%增长到了11.05%.%In order to explore the changes of fish early resources before and after the impoundment of the first phase of the Jinsha River hydroelectric project, the investigations of fish early resources were carried out at Jiangjin section from May 5 to July 10, 2011-2015. Gobiobotia filifer was selected as the main research object in this experiment in the upper Yangtze River. The results show:from 2011 to 2015, during the 335 days' survey, 1492 eggs of G. filifer were collected in 135 days. The recruitments of eggs at Jiangjin section were estimated as 7. 18 × 107 , 5. 54 × 107 , 2. 62 × 107 , 9. 85 × 107 and 14. 11 × 107 ind. respectively. It was one of largest populations of fishes which spawn drifting eggs in the upper Yangtze River. The relations between drifting density of eggs and main environment factors was analyzed based on Pearson Correla-tion. The results indicated that the drifting average eggs density was positively correlated with water transparency ( P <0. 01), and negatively correlated with water level, water discharge, flow velocity and conductivity (P<0. 01). From 2011 to 2015, the early resources of G. filifer showed a first declining and then an upward trend before and after the impound-ment. While its relative abundance of early resources was mounting up steadily, increasing from 4. 64% to 11. 05%.