The successful fish upstream movement through a dam/gate is closely associated with the hydraulic conditions of a fishway. To improve the passage efficiency, this study investigated the upstream swimming behaviors of juvenile grass carp, a representative fish of four major Chinese carps, under characteristic hydraulic conditions of a designed vertical slot fishway model. The impacts of different discharges and baffle lead angles on the successful movement of test fish were analyzed, and the selection of the movement trajectory was studied through overlay of their upstream swimming trajectories on the water flow field resulting from numerical modeling. We found that under the same discharge, the percentage of successful test fish movement with a lead angle of 45° was higher than 60° and 30°. Within a fixed lead angle, the higher the discharge, the lower the percentage of successful movement. During upstream movement, the test fish had a preferred water velocity of 0.01–0.45 m/s in the pool, and avoided areas where the turbulence kinetic energy (TKE) was greater than 0.012 m²/s². These results provide a basis for the hydraulic design of vertical slot fishways and a reference for studying swimming behaviors of other fish species.

中文翻译：

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幼草鲤鱼上游游泳行为与垂直槽鱼道特征水力条件的关系

鱼通过坝/闸门成功地向上游运动与鱼道的水力状况密切相关。为了提高通过效率，本研究调查了在设计的垂直槽鱼道模型的特征水力条件下，幼年草鱼（四种主要鲤科鱼类的代表鱼）的上游游动行为。分析了不同流量和挡板导角对试验鱼成功运动的影响，并通过数值模拟将上游游动轨迹叠加在水流场上，研究了运动轨迹的选择。我们发现，在相同的排放量下，铅垂角为45°的成功试验鱼移动的百分比高于60°和30°。在固定的导程角内，放电越高，成功移动的百分比越低。在上游运动过程中，试验鱼在池中的水速优选为0.01–0.45 m / s，并避免湍流动能（TKE）大于0.012 m的区域² /秒²。这些结果为垂直槽鱼道的水力设计提供了依据，也为研究其他鱼类的游泳行为提供了参考。