Strategic methodology to set priorities for sustainable hydropower development in a biodiversity hotspot.

Massive exploitation of freshwater systems for hydropower generation in developing countries is challenging sustainability due to cumulative environmental impacts in regions with high endemism. Habitat fragmentation is recognized as a major impact on river ecosystems. The nature and magnitude of connectivity loss depend on characteristics of the hydropower projects, and of the threatened fish communities. In areas where appropriate mitigation technology is lacking, there is a need to identify the fish species that are most at risk to better concentrate efforts. This paper aimed to set conservation priorities for sustainable hydropower development by analyzing native fish species and project characteristics. The Chilean ichthyogeographic province, an ecoregion with high endemism and massive hydropower projects development, has been considered as a case study. By using overlapping information on the characteristics of 1124 hydropower projects and distribution of native fish species, we identified three project categories of projects based on their need for mitigation. These were projects where mitigation was considered: a) not required (15%), b) required and feasible (35%), and c) required but challenging (50%). Projects where mitigation was not required were located at sites where native fish were absent and/or where water intakes allowed fish to pass. Interestingly, projects where mitigation was feasible were inhabited by a species assemblage that comprised the genus Trichomycterus, Diplomystes and Percilia, and the species Ch. pisciculus and B. maldonadoi. This finding emphasizes the need to develop a multispecific fishway that can accommodate this group. Projects where mitigation would be difficult to achieve were located at sites with a variety of different assemblages, thus making a standard fish pass solution challenging and site-specific. This study advances understanding for the need to develop mitigation strategies and technologies in ecoregions of high endemism threatened by hydropower and to prioritize the construction of planned projects.