Conservation Priorities for Threatened and Restricted-Range Freshwater Fishes in the Northeastern Mata Atlântica Freshwater Ecoregion, Brazil

In light of the growing loss of aquatic biodiversity amid the current freshwater biodiversity crisis, systematic conservation planning is crucial for developing conservation policies to establish new protected areas that effectively address the complexity of freshwater environments. This study aims to identify priority basins for conservation of threatened, near-threatened, and restricted-range endemic freshwater fish species in the Northeastern Mata Atlântica freshwater ecoregion, highlighting irreplaceable and critical locations for conservation and impact mitigation. Through spatial prioritization, three scenarios with distinct conservation features were considered: (a) 35 threatened species, (b) 118 near-threatened and restricted-range species, and (c) all 153 species. A total of 50 and 89 basins were prioritized in the first two scenarios, respectively, and 135 basins in the third scenario, with 36 classified as critical due to environmental stressors, particularly in the Rio Doce basin. Our results suggest that the current protected area network is insufficient for safeguarding most target fish species. This study presents an initial framework for prioritizing areas that can provide a basis for further, more refined assessments and to support conservation policies such as national or regional action plans, protecting basins and species.