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.