The Effects of Negative Water Pressure and Pressure Variation on the Fingerling Adaptability of the Four Major Chinese Carps

The construction of the dam blocks fish migration. The complex flow passage construction and the hydrodynamic characteristics in a turbine may cause the entrained fish damage or even death. In order to optimize the flow passage of hydraulic turbine and reduce the damage probability of the entrained fish, it is important to investigate the relationship between the pressure characteristics of hydraulic turbine and fish adaptability. A combined model simulation, video analysis, and biological anatomy method is proposed to get the effects of pressure on fish. The four major Chinese carps, typical migratory fishes in Yangtze River, are used as the research objects. The results suggest that among the four species, the adaptation ability to negative pressure in the order as: black carp, grass carp, bighead carp, and silver carp. The injuries degree and mortality of test fish to negative pressure depended on the minimum pressure value and the pressure reduction rate. The injury pressure threshold of four major Chinese carps is 20KPa. These results can further guide the “Fish-friendly” turbine design and the optimization of “Fish-friendly” passage structure.