为了解桑河二级仿自然鱼道的过鱼效果,采用水力学条件监测、红外线水下视频监测和下闸排空捕捞的方法对鱼道内的水力学参数及过鱼种类组成、体型分布等进行统计分析。结果表明:鱼道内蛮石缝间的平均流速为0.79 m/s,通道内的平均流速为0.635 m/s,符合流速设计要求。监测期间调查统计到过鱼数量共计3 954尾,隶属9目、14科、21属、24种,种类组成以鲤形目为主,占75.99%,鱼类个体数量以头孔无须魮最多,黄尾短吻鱼、裂峡鲃次之,过鱼体型集中在体长10~20 cm、体宽0~5 cm范围内。鱼类洄游游向不同并具有昼夜差异和季节差异,监测到的鱼类中有68%通过鱼道上溯,白天(6:00~18:00)过鱼效果显著优于其他时段,过鱼季节集中在7—8月份,原设计过鱼季节选在4—8月份基本合理。桑河二级仿自然鱼道为鱼类洄游提供了通道和适宜的水流环境,具有良好的过鱼功能,对该流域的鱼类保护具有重要的意义。

[Objective] With the continuous expansion of China’s water conservancy infrastructure, hydraulic structures such as dams and sluice gates have obstructed fish migration routes and altered hydrological regimes both upstream and downstream. These changes have led to fragmentation of fish habitats, population declines, and even pushed some endemic fish species to the brink of extinction. To protect aquatic biodiversity and restore river connectivity, fishways have been widely implemented as critical passage facilities. Post-construction monitoring of fishway effectiveness is essential for verifying performance and identifying potential design improvements to enhance functionality and operational management. [Methods] This study evaluated the performance of the nature-like fishway at Sanghe River Secondary Hydropower Station through comprehensive monitoring. Hydrodynamic conditions were assessed using an Acoustic Doppler Current Profiler (ADCP) and 3D acoustic Doppler velocimeter (ADV) to measure water depth, temperature, and velocity parameters, ensuring they met fish passage requirements. Fish passage was monitored using infrared underwater video surveillance and capture methods during periodic dewatering, with data collected on species composition, abundance, size distribution, and movement patterns, providing references for domestic studies on nature-like fishway construction and fish passage monitoring. [Results] Results indicated all hydrodynamic parameters met design specifications. During monitoring, reservoir levels remained stable at 75 m, with fishway depths fluctuating between 0.03-1.22 m. Average velocities were 0.79 m/s in boulder crevices and 0.635 m/s in main channels, creating suitable migratory conditions. A total of 3 954 fish from 24 species (9 orders, 14 families) were recorded, dominated by Cypriniformes (75.99%). The most abundant species were Crossocheilus reticulatus, followed by Sikukia flavicaudata and Hampala macrolepidota, with most fish measuring 10-20 cm in length and 0-5 cm in width. Migration patterns showed distinct temporal variations: 68% of fish moved upstream, with significantly greater passage efficiency during daylight hours (06:00-18:00). Peak migration occurred in July-August, validating the design assumption of April-August being the primary migration season. [Conclusions] Measures to improve fish passage effectiveness include optimizing power generation-fishway coordination, removing debris in front of dam,dredging and maintaining fishway, and regular cleaning of monitoring equipment to improve reliability. The nature-like fishway at Sanghe River has successfully reestablished connectivity and created favorable hydrodynamic conditions for fish migration, demonstrating significant conservation value for the basin’s ichthyofauna.