长江上游江津断面铜鱼鱼卵时空分布特征及影响因子分析

为了解金沙江一期工程蓄水前后的长江上游铜鱼繁殖情况,2011—2014年每年5月5日—7月10日,在江津江段通过使用圆锥网捕捞鱼卵,定点进行早期资源调查。结果显示,在采集到的8 014粒鱼卵中铜鱼鱼卵数量最多,占总鱼卵数的14.76%。调查期间江津江段铜鱼卵苗年均年总径流量为22.45×10⁷尾。2011年—2014年江津江段铜鱼鱼卵日均密度各年平均值分别为8.41、10.57、1.32和3.18个/1 000 m³,2013年和2014年铜鱼鱼卵日均密度显著低于2011年和2012年。对铜鱼鱼卵日均密度与水文环境因子进行相关性分析,发现鱼卵日均密度与透明度呈显著负相关,而2013年和2014年透明度显著高于2011年和2012年。根据鱼卵发育时期和流速推测江津白沙至羊石及榕山至兆雅两个江段为铜鱼的主要产卵区域,该区域铜鱼产卵量约占铜鱼产卵总量的56.96%。研究表明,金沙江一期工程蓄水对铜鱼产卵行为产生了影响,建议工程运行期间应根据长江上游铜鱼的产卵条件进行科学调度,并禁止在产卵江段进行捕捞。

Spatial and temporal distributions and influence factors of brass gudgeon (Coreius heterodon) eggs in Jiangjin section of the upper Yangtze River

In order to study the reproduction of brass gudgeon (Coreius heterodon) in the upper Yangtze River before and after impoundment of the first phase of the Jinsha River Hydroelectric Project(including Xiangjiaba and Xiluodu Dam),the surveys of fish resources of early life stages were carried out in Jiangjin section from May 5 to July 10,2011-2014.Sampling was conducted continuously by conical net.The results showed that C.heterodon accounted for 14.76% of the total 8 014 eggs,the annual average fecundity of C.heterodon was 22.45×10⁷ind.From 2011 to 2014 average daily density of C.heterodon eggs were 8.41,10.57,1.32 and 3.18 ind./1 000 m³ respectively,the average daily density of 2013 and 2014 had significant difference with 2011 and 2012.The correlation between density of C.heterodon eggs and its influence factors found that C.heterodon spawning had significant negative correlation with the transparency,and the transparency of 2013 and 2014 was significantly higher than transparency of 2011 and 2012.According to egg developmental stage and flow velocity,it was inferred that Baisha to Yangshi and Rongshan to Zhaoya section were the main spawning grounds,which were contributing about 56.96% of the total C.heterodon eggs.It indicated that the Jinsha River Hydroelectric Project brought certain impacts to C.heterodon spawning in the upper reaches of Yangtze River,the operation of the first phase of the Jinsha River Hydroelectric Project should consider the environmental requirement of C.heterodon spawning,and a complete fishing ban in spawning grounds should be implernented.