A Family-Level Evaluation Of The Drivers Of Fish Invasions

The ability to predict the establishment of non-native fishes is critical to preventing their spread and conserving native fishes, but the drivers of fish invasions are relatively unclear; potentially (in part) due to the biological scale (e.g., species richness) that invasions are commonly evaluated.  We used fish community samples (n=163) from the Upper Colorado River Basin to evaluate the drivers of non-native fish occurrence at the family taxonomic level.  We calculated metrics of anthropogenic alteration to flow regime, physical habitat, water quality, and energy source using the density and severity of landscape-level threats as measures of habitat alteration.  Non-native cyprinid (e.g., fathead minnow Pimephales promelas) occurrence increased with habitat alteration, but decreased with increased native salmonid presence.  Non-native salmonid (e.g., brook trout Salvelinus fontinalis) occurrence decreased with increased presence of native salmonids and cyprinids.  However, non-native catostomid (e.g., white sucker Catostomus commersonii) occurrence increased with the presence of native catostomids and habitat alteration.  Habitat alteration and native fishes may be useful predictors of future invasions, but the drivers of invasions vary by taxa.  A taxonomic approach may be an informative approach for identifying the drivers of species invasions across large geographic areas.