Study on the spawning period of typical fishes in the lower reaches of Jinsha River under the influence of water temperature change

To analyze the influence of the water temperature change in the lower reaches of Jinsha River on the spawning period of typical fishes before and after the completion of the Xiangjiaba Dam, the interannual water temperature trend and the variation range in recent years are analyzed and studied based on the measured data; and then the suitable water temperature range of 14 typical fish species in the historical spawning period is projected to the change curve of current water temperature, so as to obtain the variation of spawning period. The influence of water temperature change on the spawning activity is quantitatively evaluated by the proposed index of time overlap. The results show that the rise period of temperature in the lower reaches of Jinsha River before the dam construction is from February to June, and the annual variation range is 11.8 to 23.2℃. After the dam is built, it is postponed to April-July, with the variation range of 14.0 to 23.1℃, and the temperature fluctuations show a decreasing trend. Under the water temperature condition after the dam construction, the main spawning period of typical fishes in the lower reaches may move from early March-late July to late March-early August.