Assessing coverage of freshwater fish data in the United States

Study shows large bias towards flowing water bodies and calls for increased focus on surveying still waters, like lakes and dam reservoirs

Data resources used via GBIF : 557,680 species occurrences
Notropis percobromus
Carmine shiner (Notropis percobromus) collected in 2014 from Apple River near Elizabeth, Illinois. Specimen via the Field Museum, photo licensed under CC BY-NC 4.0.

The work of researchers testing ecological and evolutionary hypotheses using primary biodiversity data, like species occurrences in, depend on the evenly distribution of ecological surveys in both space and time. The ecological coverage of freshwater habitats having a disproportionately high number of species, is largely unexplored and thus in urgent need of assessment.

Through compilation of all available freshwater fish records from GBIF, the Multi-State Aquatic Resources Information Facility (MARIS) and federally administered fish survey (FFS), authors of this paper set out to assess the completeness of freshwater fish data in the contiguous United States.

Having standardized taxanomic nomenclature across the entire dataset of 1.5 million occurrences of 21 million individuals across 892 species, their analysis revealed spatial and temporal differences between the three sources. FFS data was sparse but widespread, whereas GBIF data was dense in coastal regions, however, spanned more years than FFS or MARIS data.

Overall, more than 95 per cent of data originated from flowing waters such as springs and rivers, suggesting that while data on freshwater fish is plentiful, future surveys should focus on still waters–like lakes and reservoirs–to improve completeness.

Link to original article

Troia MJ and McManamay RA (2017) Completeness and coverage of open-access freshwater fish distribution data in the United States. Diversity and Distributions. Wiley 23(12): 1482–1498. Available at: