长江上游宜宾江段鱼类早期资源现状研究

Study on the Status of the Early-Stage Fish Resources at Yibin Section in the Upper Reaches of the Yangtze River

本研究于2017―2019年每年4―7月在宜宾江段开展鱼类早期资源调查。结果显示,宜宾江段有鱼类22种,隶属于3目5科,以鲤科(Cyprinidae)鱼类为主,其中,产漂流性卵鱼类13种,特有鱼类6种。不同鱼类繁殖时间具有明显的年内和年间差异,但均在6月进入繁殖盛期。2017―2019年,鱼卵总径流量分别为12.10×10^(6)、70.42×10^(6)和35.77×10^(6)粒,鱼苗总径流量分别为30.95×10^(6)、41.47×10^(6)和39.44×10^(6)尾,其中,特有鱼类3年累计总卵径流量为15.91×10^(6)粒。经推算,在宜宾江段分布着多个产漂流性卵鱼类的产卵场,规模较大的产卵场主要分布在周坝、桃子湾和华龙码头3处。吻(Rhinogobio typus)产卵场从东岳庙至向家坝坝下均有分布,3年累计产卵量最大达40.93×10^(6)粒,且吻产卵场有向下游迁移的趋势。草鱼(Ctenopharyngodon idellus)产卵场主要分布在马铭溪码头和桃子湾。CCA分析结果显示,水位、水温和流量等环境因子对鱼卵密度有不同程度的影响,犁头鳅(Lepturichthys fimbriata)和花斑副沙鳅(Parabotia fasciata)在水温和流量较高时产卵;草鱼和小眼薄鳅(Leptobotia microphthalma)繁殖条件相近,与水位、流量和流速相关性较高;吻和铜鱼(Coreius heterokon)产卵受溶解氧和透明度变化的影响较大。虽然受到金沙江下游梯级水电开发等多种因素的影响,但宜宾江段作为保护区的重要组成部分,仍是多种鱼类产卵繁殖的重要分布区,近年来,资源量呈上升趋势缓慢恢复。建议加强该江段早期资源研究,开展生境保护与修复,落实好“十年禁渔”,以促进资源恢复。

To understand the status of early-stage fish resources in the Yibin Section in the upper reaches of the Yangtze River and guide the protection of fish resources in this section,surveys were carried out from April to July in the years of 2017~2019.The results showed that there were 22 species of eggs and larvae in five families and three orders,and the largest proportion was in the Cyprinidae.Among these,13 species produced drifting eggs,and six species were endemic to the upper reaches of the Yangtze River.The breeding time of different fish had obvious annual differences,but the peak of fish breeding occurred in June.From 2017 to 2019,the number of drifting eggs was estimated to be 12.10×10^(6),70.42×10^(6),and 35.77×10^(6) for each year,respectively.The number of larvae was estimated to be 30.95×10^(6),41.47×10^(6),and 39.44×10^(6),respectively.The number of eggs of endemic fish in the upper reaches of the Yangtze River was estimated at 15.91×10^(6) over three years.According to the calculation,there were many spawning sites of fish drifting upstream of the Yibin Section,and the larger spawning sites were mainly located in the reaches of Zhouba,Peachwan,and Hualong Wharf.The spawning sites of Rhinogobio typus were distributed from Dongyuemiao to Xiangjiaba,with the largest cumulative spawning amount in three years,up to 40.93×10^(6).The spawning grounds of R.typus tended to migrate downstream.The spawning grounds of Ctenopharyngodon idellus are mainly distributed in the Mamingxi Wharf and Peachwan areas.The results of the canonical correlation analysis showed that environmental factors such as water level,water temperature,and water discharge had different effects on the density of drifting fish eggs.Lepturichthys fimbriata and Parabotia fasciata lay eggs when the water temperature and water discharge are high.The reproductive conditions of C.idellus and Leptobotia microphthalma were similar to each other,and they were highly correlated with the water level,water discharge,and velocity.The spawning of R.typus and Coreius heterokon was significantly affected by changes in dissolved oxygen and transparency.Although affected by many factors,such as the development of cascade hydropower in the Jinsha River,the Yibin Section,as an important part of the mainstream national nature reserve of rare and endemic fish in the upper Yangtze River,is still a crucial distribution area for the spawning and breeding of many fish species,and the fish populations have slowly recovered in recent years.Therefore,we should strengthen the early resource research in this section,carry out habitat conservation and remediation,and implement a“10-year Fishing Ban”to promote resource recovery.