Ecological niche models as tools for freshwater fish conservation in a changing world

Freshwater biodiversity faces escalating threats from habitat loss, invasive species, and climate change, necessitating advanced conservation tools, such as spatial prioritization frameworks and ecological niche models (ENMs), which are increasingly valuable in freshwater fish conservation, allowing researchers to predict species distributions based on environmental and species detection data sets. Yet their adoption in freshwater ecosystems has lagged due to unique challenges like the dendritic nature of stream networks, data scarcity, and limited spatially continuous environmental predictors. Recent advances integrating fine-scale hydrological attributes and high-resolution topographic data have significantly enhanced ENM accuracy. Here, we used case studies spanning data-rich and data-poor riverscapes (i.e., Pacific Northwest of North America, South America, and the Himalayas) to showcase some applications of ENMs for freshwater fishes to evaluate habitat change due to climate change, habitat overlap between native and nonnative species, and hybridization risk between native and nonnative salmonids. Expanding ENM application in freshwater ecosystems promises improved conservation outcomes for fisheries management and conservation practitioners by identifying critical habitats and informing targeted management strategies.