汉江下游鱼类早期资源及梯级联合生态调度对鱼类繁殖影响的初步分析

Preliminary Analysis of the Fish Larvae and Eggs and the Effects of the Eco-operation of Cascade Reservoirs on Fish Propagation in the Lower Hanjiang River

汉江是长江一级支流,鱼类资源较为丰富。目前汉江中下游建有4座水利枢纽工程,对鱼类洄游和繁殖产生较大影响。在鱼类繁殖季节,为促进汉江中下游鱼类繁殖,2018年6月汉江中下游首次实施梯级联合生态调度。该研究在汉江下游汉川段设置监测断面,采集鱼类早期资源,以分析汉江下游鱼类早期资源多样性,及生态调度对促进汉江下游鱼类繁殖的效果。监测结果表明汉江下游卵苗种类共有36种(属),其中22种为产漂流性卵鱼类。监测期间卵苗总径流量为118.78亿尾(粒),其中四大家鱼卵苗为0.87亿尾(粒),占0.73%,其中鱼卵0.69亿粒,推测汉江下游有4处四大家鱼产卵场。梯级联合生态调度期间,汉川江段出现一次鱼类产卵高峰,鱼卵径流量占总径流量的34.1%,其中四大家鱼鱼卵占家鱼卵总径流量的85.5%,表明梯级联合生态调度对汉江下游鱼类,特别是四大家鱼的繁殖具有积极的作用。建议今后继续开展生态调度,并加强监测和分析工作。

The Hanjiang River is a tributary of the Yangtze River, where the fish resources are rich. At present, there are four dams having been constructed in the middle and lower reaches of the Hanjiang River, which have greatly influenced on fish migration and reproduction. In order to promote fish propagation in the middle and lower reaches of Hanjiang River, the combined eco-operation of cascade reservoirs was firstly carried out in June 2018. In this study, we set up a monitoring station in Hanchuan, locating in the lower Hanjiang River, to capture the fish larvae and eggs. Our aims were to study the species diversity and abundance of fish early life resource and the effects of eco-operation on the fish reproduction in the lower Hanjiang River. The results revealed that thirty-six fish species or genus were identified from the captured larvae and eggs, twenty-two of which produced drifting egg. The total quantity of fish larvae and egg was 11.878 billion, with 11.378 billion of larvae and 0.55 billion of egg. The total quantity of four domestic Chinese carps’ larvae and egg were estimated to be 87 million and accounted for 0.73 percent of total larvae and egg. Four spawning grounds of four domestic Chinese carps in the lower river were deduced according to the development time of fish egg and water velocity. During the combined ecol-operation of cascade reservoirs of the Hanjiang River, a spawning peak was found in the lower reaches and the egg abundance of the peak accounted for 34.1 percent. A spawning peak of the four Chinese farmed carps was also detected in this period and the egg abundance accounted for 85.5 percent of all captured these fishes’ egg. It indicated that eco-operation of cascade reservoirs had a positive effect on fish reproduction activities in the lower Hanjiang River, especially for the four domestic Chinese carps. We suggested that ecol-operation should be continuely scheduled and the monitoring works and data analysis should be focused in the future.