Effects of ecological operation of Three Gorges Reservoir on larval resources of the four major Chinese carps in Jianli section of the Yangtze River

In order to explore the effect of ecological operation of Three Gorges Reservoir on breeding of the four major Chinese carps in Jianli section of the Yangtze River, and evaluate the quantitative range of ecological hydrology indexes that stimulate spawning behavior of four major Chinese carps, in this study, we investigated the early life resources of the Four Major Chinese Carps in Jianli section of the middle reaches of the Yangtze River, from May to July, 2013—2017. Correlation analysis was made between the Four Major Chinese carps’ spawning and larvae collected and the ecological hydrology index. The results show that there is a significantly positive correlation between the daily flow increasing rate and the quantity of fish eggs. When the duration is 4 d and more, and the daily flow increasing rate is from 1 600 to 2 833 m³/(s·d), ecological operation is more effective to stimulate the reproduction of the Four Major Chinese Carps in late June. Preliminary results indicated, water rising of ecological operation of Three Gorges Reservoir has improved the hydrological conditions for the breeding of four major Chinese carps in Jianli section. The implement of ecological operation not only reduced the negative impact on fish breeding in the midstream of the Yangtze River, but also maintained fish population resources after the operation of the Three Gorges Reservoir.