长江上游江安段鱼类早期资源调查

Fish resources of early life in the Jiang’an section in the upper reaches of the Yangtze River

为了解长江上游江安段鱼类繁殖状况,于2022年4—5月在该江段采用底层采卵网进行鱼类早期资源调查,鱼卵使用解剖镜观察分类,并通过分子生物学方法进行鉴定。结果显示,至少有20种鱼类在江安段繁殖,其中产漂流性卵鱼类11种,长江上游特有鱼类3种。监测期间,S1和S2位点出现4次产卵高峰,S3位点出现5次产卵高峰,估算通过江安段的鱼卵总径流量为3.94×10^(8)粒。冗余分析显示,水温、pH、溶解氧、透明度、流速和流量等环境因子对鱼类产卵活动产生不同程度的影响。研究表明,江安段是多种鱼类的产卵场,鱼类早期资源规模较大,但多样性较为贫乏,长江鲟、胭脂鱼以及岩原鲤并未监测到自然繁殖,同时,流量的增减对鱼类的自然繁殖活动有刺激作用。建议继续科学适宜地开展增殖放流,并开展长江上游梯级水电站生态调度研究,以满足长江上游鱼类繁殖需求。

The upper reaches of the Yangtze River,with its special geology,geomorphology,climate and natural ecological environment,has bred a rich diversity of fish.However,in recent years,the fishery resources have been declining significantly due to the development of water conservancy projects and the increase of human fishing intensity.As a buffer zone of the“National Nature Reserve for the rare and endemic fishes in the upper reaches of the Yangtze River”,the Jiangan section in the upper reaches of the Yangtze River is rich in fish resources.Surveys were carried out in the Jiangan section from April to May in 2022 to study the fish resources of early life.The eggs were identified by molecular biology methods.At least 20 species of fish breed in the Jiangan section,including 13 species of drifting eggs and 3 species of endemic fish in the upper reaches of the Yangtze River.During the monitoring period,there were 4 spawning peaks at S1 and S2 sites,and 5 spawning peaks at S3 site.It is estimated the total fish eggs passing through the Jiangan section is 3.94×10^(8) ind.The Shannon-Wiener diversity index,Margalef richness index,Pielou evenness index and Simpson index of the Jiangan section ranged 0.306-0.496,1.636-2.087,0.10~8-0.169,and 0.816-0.885,respectively.Environmental factors such as water temperature,pH,dissolved oxygen,transparency,water level and water discharge were found to have different degrees of influence on egg density through redundancy analysis.The research results showed that the Jiang’an section was spawning ground for a variety of fish,and the early resources were large in scale but poor in diversity.The natural reproduction of Acipenser dabryanus,Myxocyprinus asiaticus and Procypris rabaudi was not monitored.The increase and decrease in water discharge had a stimulating effect on fish reproduction.Therefore,it is suggested to continue to carry out breeding and releasing scientifically and appropriately and carry out ecological dispatching research to meet the breeding demand of fish in the upper reaches of the Yangtze River.