Number of Fish Species by Freshwater Ecoregion

Number of freshwater fish species, by freshwater ecoregion. The map of freshwater fish species richness—the number of species present in each ecoregion—was generated from a variety of sources by Abell et al. (2008). Only species using freshwater for at least a portion of their life cycles, as identified using the habitat assignments in FishBase, are included. For the United States, NatureServe provided presence/absence data for individual species, coded to eight-digit hydrologic unit codes (HUCs); these HUC occurrences were then translated into ecoregions, and the data were manually cleaned of erroneous occurrences derived from species introductions and problematic records. For all other ecoregions, species lists were provided by [...]