Author(s): Lei Tang; Yuxing Zhang; Yuqing Lin; Qiuwen Chen
Keywords: Chinese carps; Numerical simulation; Spawning conditions; Velocity; Velocity variability
Abstract: The four major Chinese carps are important commercial fishes in China which mainly live in the Yangtze River. However, the regulation of large reservoirs in Yangtze River changed hydrological conditions of river and blocked the migration route, which affected spawning behavior of the four major Chinese carps seriously. According to recent survey, the populations of the four major Chinese carps was gradually reduced year by year, especially after the construction of Three Gorges Dam. In order to protect fish species and improve the fish population, the suitable conditions for spawning of the four major Chinese carps need to be studied. In this paper, two-dimensional hydrodynamic model was applied to simulate the flow dynamics from Yichang to Yangjiazui. Based on the survey data of the four major Chinese carps’eggs captured at Yidu section from May to July in 2014～2016, the spawning locations in the study area were calculated. Choosing velocity and velocity variability as the key driving factors, the suitable spawning condition required by the four Chinese carps was analyzed by establishing relationship between velocity, velocity variability and spawning. The trigger velocity for four major Chinese carps’spawning ranged from 1.11 to 1.49 m/s. The suitable velocity ranged from 1.40 to 1.60 m/s. The suitable velocity variability ranged from 0.04 to 0.12 (m/s) /d. This research can provide theoretical basis to recover spawning ground for four major Chinese carps, and also support reservoir biological regulation as technical reference. It has great significance for promoting the four major Chinese carps spawning benefits and maintain the sustainable development of fisheries resources in the middle reach of Yangtze River.