This dataset provides a distribution of fish species by HUC across the United States. The dataset was created in 2013 using the 8-digit Watershed Boundary dataset, disributions of all North American freshwater fish species from Nature Serve (http://www.natureserve.org/getData/fishMaps.jsp), and ESA/IUCN listed status information from NatureServe Exporer (http://www.natureserve.org/explorer/). Although the ESA provides a federal listing of species or candidates for listing, the vulnerability of organisms to habitat modification may not be fully captured by federal listing alone. IUCN developed a 9 tiered ranking status based on evidence of extinction, population changes within the last 10 years (or 3 generations), the extent of an organism’s geographical range, the occupancy within that range, population size, and the availability of data. Only the ranking status of extant fish was considered. IUCN ranks include critically endangered, endangered, vulnerable, near threatened, least concern, data deficient, and not evaluated. Critically endangered organisms are considered to be at high risk of extinction, with decreasing extinction risks from rankings at endangered to least concern. Thresholds for each category are provided in the IUCN Red List Categories and Criteria (IUCN, 2001).
Tables of HUC08s for each fish species were merged into a single composite dataset and joined to lists of federal listing status and IUCN ranking by scientific name. Numbers of fish species within each status/ranking category were summarized for each HUC08.
Descriptions of IUCN criteria are available from: IUCN (International Union for the Conservation of Nature) (2001), IUCN Red List categories and criteria: Version 3.1, IUCN Species Survival Commission, IUCN, Gland, Switzerland and Cambridge, UK.