Review of the Impact of Water Project on the Four Major Chinese Carps in the Yangtze River and the Corresponding Ecological Measures

Major Chinese Carps are the main economy fishes in China, and the Yangtze River is an important place with high-quality germplasm resources of the Four Major Chinese Carps. However, the population and the spawning quality of the four Chinese carps in the middle and lower reaches of Yangtze River are in decline currently. It is generally considered that water conservancy projects is the leading cause of the changes in the flow regime of the natural rivers. Based on a review of the ecological and hydrological factors affecting the spawning of the Four Chinese Carps, this paper tried to categorize the changes in the hydrological regime in the middle and lower reaches of the Yangtze River over years and the changes in the spawning grounds of the Four Chinese Carps. The hydrodynamic conditions of the Four Chinese Carps spawning grounds and their natural reproduction were also summarized. Furthermore, this paper analyzed the effects of Gezhouba and Three Gorges water conservancy projects on the hydrological situation and the reproduction of the Four Chinese Carps. Meanwhile, China Three Gorges Corporation (CTG) has monitored the spawning and population changes of Four Chinese Carps since beginning of the environmental impact assessment (EIA) of the Three Gorges Project in 1991. According to the long-term study of the four major Chinese carps, CTG has enforced ecological regulations to simulate the natural flood peaks during the spawning period of four major Chinese carps from May to August to enlarge the scales of fish populations since 2011, then to monitor their spawning and hatching at the downstream. To some extent, this measure would gradually help recover the populations of four major Chinese carps in the middle and lower reaches of the Yangtze River.