Potential benefits to the endemic fish habitat in the highland deeply incised high-energy river responding to hydropower development

The implementation of hydropower development in the Yarlung Tsangpo River (YTR), one of the largest rivers originating on the Qinghai Tibetan Plateau, has the potential to contribute to carbon neutrality. This study aimed to investigate the potential ecological impacts of upcoming hydropower development on the endemic fish habitats in YTR and to explore a possible balance between power generation benefits and fish habitats protection. A systematic field investigation was conducted on the logistically-challenging and data-lacking YTR, and accurate digital channel topography was generated. The potential changes in habitat of the endemic fish species Schizopygopsis younghusbandi were simulated under the different scenarios of coming hydropower operation modes, i.e., maximum energy mode (ME) and flood peak weakened mode (FW). The results showed that the habitats for non-spawning adults could be improved during hydropower operation throughout the whole year, especially under the ME mode that weighted useable area for fish (WUA) was increased by 21.3% on average. The spawning area could be increased by 2% on average under both modes. However, the habitats for juveniles could be reduced during spring and winter under both FW and ME operation modes. Following the principle of minimizing negative impacts on key life stages of the fish, a seasonally mixed operation mode of FW and ME is recommended for future to achieve both power generation benefits and aquatic ecology protection. This study extends the understanding of sustainable hydropower development in extremely high energy rivers and will benefit nature-based solutions for deeply incised rivers over the world.