Defining Native Ranges of U.S. Inland Fishes

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The Science Issue and Relevance: Despite knowing a great deal about species distributions, there is surprisingly no database on the native ranges of conterminous United States and Alaska fishes. Freshwater fishes’ ranges have been dramatically affected by changes in land use and water flow, for example, by damming rivers. It is important to distinguish between a species' native (indigenous) range where it has historically originated and lived and its non-native (nonindigenous) range where a species has more recently established itself. Understanding the native versus non-native range of a species can provide information about dispersal, population distribution patterns, and human mediated movement across hydrologic barriers. This information is also useful for the U.S. Geological Survey Nonindigenous Aquatic Species (NAS) database as the native range provides the basis of knowing if a sighting of a fish should be included in the database.

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Methodology for Addressing the Issue: Native ranges were defined for a subset of fishes selected by the NAS program, with consultation from collaborators from Michigan State University and the U S. Geological Survey Gap Analysis Program. Fish species selected had to meet certain criteria: fishes must be currently tracked by NAS as native transplants, considered Landscape Conservation Cooperative priority species, and managed by states as a game species. In the first round in 2017, native ranges were defined for 63 species/subspecies. In 2018, the native range of 102 species and subspecies were defined (see Table 1 for full list of species). In 2019, the list includes 65 species.

In order to determine the native range for each species, information generated by NatureServe was used. However, the NatureServe dataset includes both native and non-native occurrences and has many large data gaps. That distribution was enhanced with sample locations from the National Fish Habitat Partnership’s fish dataset, which included aggregated fish community samples from various state and federal agency sampling programs since 1990, and the Global Biodiversity Information Facility which integrates numerous museum biodiversity collections. These data were brought into ArcGIS and displayed by eight-digit hydrologic unit codes. The known non-native locations of the species were added from the NAS database. Historical scientific literature, including state fish books, agency reports, and journal publications, was then reviewed to determine the original native range of the species. The defined native ranges went through multiple reviews by NAS scientists. For fishes tracked by the NAS program, the native ranges can be found on the species profile. All native range data for these species will also be made available via an Application programming interface (API) which will be used by U S. Geological Survey Core Science Analytics, Synthesis, and Libraries.

Future Steps: The NAS program is working on a third installment of the fish native ranges for 2019 and have selected a new set of 65 species using the previous criteria. The third installment of native ranges will be completed by June 2019.