Evaluating the Ecological Impact of the Laluo Hydropower Station on Fish Migration and Spawning Habitats in Plateau River Systems

Abstract

To assess the impact of the Laluo Hydropower Station on fish community structure and spawning habitat, hydraulic and ecological surveys were conducted in typical upstream and downstream of the station, and the physical biotopes distribution and fish community composition were obtained. By comparing the differences in fish community structure and spawning environment factors between the natural river sections and the downstream river section of the dam, analyse the impact of the station on the spawning grounds of fish in the downstream reaches of the dam and extract the main influencing factors. Results showed that the fish community in the study area is composed of Schizopygopsis younghusbandi, Schizothorox waltoni and Triplophysa spp., with S. younghusbandi being the dominant species. The physical biotopes of the spawning grounds for S. younghusbandi includes pools or glide, with a water depth of 0.3 ~ 1.0 m, flow velocity < 0.3 m/s and a substrate primarily consisting of fine particles such as sand and fine gravel. Downstream, the number of sexually mature individuals was low, with a skewed sex ratio, indicating significant spawning ground degradation. Water temperature, altered by the station's operation, was identified as the main factor disrupting spawning. This study contributes to the existing body of data and case studies in the field, advancing research on fish habitats in plateau rivers. It holds significant implications for the conservation of fish resources and the preservation of healthy aquatic ecosystems in these regions.