三峡库区丰都江段鱼类早期资源现状

2014 年47 月鱼类主要繁殖季节于三峡库区(重庆丰都县)进行鱼类早期资源调查, 以了解三峡库区鱼类早期资源现状, 四大家鱼在库区是否仍有产卵场等问题。调查共采集到鱼类50 种, 分属5 目9 科。采集时, 卵汛出现在6 月后流速较高的时段, 其中贝氏的数量最多, 占86.24%。仔鱼出现的高峰期为6 月上旬至7 月中旬, 太湖新银鱼的数量最多, 占58.36%, 其次为子陵吻虎鱼, 占27.04%。在仔鱼中, 种类组成呈明显的月份差异, 4 月鲤、鲫占数量优势;5 月太湖新银鱼、子陵吻 虎鱼占数量优势;6 月后鲌亚科、鳅科、鳜等种类开始出现, 种类明显增多。通过估算, 调查期间流经丰都断面的鱼卵总量为4.37108 粒, 四大家鱼鱼卵为0.21107 粒;仔鱼总量为111.98108 尾, 四大家鱼仔鱼为0.21108 尾。通过产卵场的推算, 丰都断面采集的四大家鱼来自涪陵城区江段和三峡库区上游的重庆巴南区至朱沱镇江段的产卵场。通过对卵苗漂流密度的昼夜规律分析, 6 月之前夜间仔鱼密度显著高于白天, 而6 月后仔鱼昼夜漂流密度无显著差异。本研究表明, 从三峡库尾进入三峡水库的鱼类早期资源丰富, 大部分鱼类繁殖发生在6 月以后水温较高、入库流量大、库区流速较高的时段, 库尾部分江段在流速较高时期, 仍存在四大家鱼的产卵场。  

THE STATUS OF THE EARLY STAGE FISH RESOURCES IN THE FENGDU SECTION OF THE THREE GORGES RESERVOIR

In this study, we evaluated the early-stage fish resources and the spawning grounds of major four Chinese carps in the Three Gorges Reservoir (TGR). We collected samples of fish eggs and larvae in the Fengdu section from April to July of 2014. There were 50 fish species that belonged to nine families and five orders. The fish eggs were abundant after June 1st, and the larvae were abundant from early June to mid July. The dominant eggs were from Hemiculter bleekeri (86.24%), and the dominant larvae were from Neosalanx taihuensis and Rhinogobius giurinus. The species composition of larvae varied in different months: Cyprinus capio and Carassius auratus were abundant in April, Neosalanx taihuensis and Rhinogobius giurinus were the most abundant species after May, and the proportion of Cultrinae and Cobitidae increased after June. We estimated that there were 0.437 billion eggs and 11.198 billion larvae drifting through the Fengdu section, including approximately 2.1 million eggs and 21 million larvae of the major four Chinese carps. The spawning grounds of the major four Chinese carps could be located in the Fuling reach and the passage from Banan to Zhutuo. The density of the larvae in the nighttime was significantly higher than in daytime before June 1st, but there was no difference after June 1st. This study suggested that a large amount of fish eggs and larvae drifted through the Fengdu section and flew into the TGR, which provided massive resources for the fishery in the TGR. The spawning time for most fishes in the TGR was post June when the water temperature, discharge and velocity were relatively higher. Moreover, there were also some spawning grounds of the major four Chinese carps at the end of the TGR.