Identifying optimal position for a fish collection system for endemic fishes in Hong River, China

Establishing a suitable location for a fish collection system is crucial for luring and collecting fish and requires the swimming characteristics of fish to be considered. This study aimed to identify a suitable location to lure fish to the fish collecting system (or barge) on the Hong River. For this purpose, a 3D computational fluid dynamics model for the downstream of dam was verified using Acoustic Doppler current Profiler (ADCP) velocity data to simulate the flow field of river channel considering of seven typical operation scenarios. The swimming performance of five endemic fish (Bagarius rutilus, Cyprinus carpio rubrofuscus, Semilabeo obscures, Channa argus, and Opsariichthys bidens) were evaluated using three indexes, i.e., induced flow velocity, critical swimming speed, burst swimming speed, to determine their migration behavior zones by analyzing different flow velocities. By adapting the simulated flow fields in each operation scenario, potential fish migration aggregation zones were analyzed. The results suggested that the most optimal position for placing the FCP was in the left bank of river channel at X = 400-500 m in typical operation scenarios. This study provides a reference for designing FCP for fish pass facilities that combine fish swimming behavior and hydraulic variables of the river channel.