Ecological perspectives of endemic fish species under cascade hydropower development

Abstract

Wang Y, Wang Q, Zhang W, Wang N, Cong N, Kattel G, Qi Y, Yao W. 2024. Ecological perspectives of endemic fish species under cascade hydropower development. Lake Reserv Manag. XXX–XXX. The upstream Lancang River basin (in Tibet) offers rich hydropower resources together with some of the most delicate freshwater fish species diversity in the world. However, a large dam construction scheme throughout the basin has threatened the fish species diversity and ecology. Our study focuses on the extent to which hydropower construction in the basin influences the river’s ecological status, including the aquatic environment, fish migration, and fish spawning sites. We surveyed the water quality, fish distribution, and fish spawning sites and estimated the fish spawning capacity in the basin. Our results indicate that the water quality prior to dam construction would meet China’s water standards. However, water quality would decline significantly following dam construction, exacerbating the rate of loss of 7 of the protected endemic fish species, as well as threatening the habitat of several other fish species. Our analysis shows a loss trend of fish populations and spawning capacity after damming the river. Cascade dams constructed in the upstream Lancang River basin would obstruct natural migration of fish and inundate their spawning sites, causing reproductive failure and population decline. Based on our analysis, and eco-hydraulic engineering principles, we recommend several ecological protection measures and management options in the upstream Lancang River basin, including the construction of artificial fish ladders, the implementation of ecological regulation, and a fish strategy that will reduce the negative effect of cascade dam constructions.