Survey on performance of vertical slot and nature-like fishways at Angu hydropower station, Southwest China

To restore dam-blocked natural fish migratory passages, a growing number of artificial fishways have been built in water conservancy and hydropower projects in China. The Angu hydropower station involved diverse important fish habitats in the lower reaches of the Daduhe River in Southwest China. Therefore, a vertical slot fishway (VSF) and a nature-like fishway (NLF) were built near the backwater area of the reservoir to connect the upstream and downstream habitats. Hydrodynamic and aquatic ecological surveys were conducted after the completion of the project to estimate the fish passing effect of the two fishways. The results indicated that both fishways were in effective operation and could maintain the desired hydrodynamic conditions and be used by several local fish species. During the survey, 149 fish from 15 species and 111 fish from 17 species were captured by the traps in the VSF and NLF, respectively, while 1 263 fish from 27 species were found in the downstream area. Some species captured in the VSF were not found in the NLF, and vice versa, which implied the different preferences of fish. Meanwhile, 3 789 signals including 2 099 upward ones and 1 690 downward ones were monitored with an ultrasonic fish detector at the inlet of the VSF. These findings revealed the characteristics of fish species observed in and near the fishways and provided valuable insights into the different fish passing capabilities of VSF and NLF.