Do fishes enjoy the view? A MaxEnt assessment of fish habitat suitability within scenic rivers

Scenic rivers programs are a potential tool to conserve freshwater habitat but few studies have attempted to characterize fish habitat within scenic rivers. Using the Virginia Scenic Rivers Program as a case study, we built species distribution models for a representative set of Virginia freshwater fishes and tested whether model-predicted habitat suitability values for scenic rivers are consistently higher than the range-wide average values. We began by selecting 33 fish species that were broadly representative of the complete functional trait space comprised by Virginia's freshwater ichthyofauna. This subset included 11 state-listed imperiled species. Next, we built maximum entropy species distribution models for each of the 33 fishes and used the models to predict habitat suitability throughout each species' range. Habitat suitability within state-listed scenic rivers was then summarized and compared with the complete, state-wide distribution of habitat suitability for each species. For 21 of 33 species, model-predicted habitat suitability was significantly higher in currently listed Virginia scenic rivers than in the state-wide distribution; of these 21 species, 5 were imperiled taxa. Furthermore, habitat suitability within scenic rivers is predicted to exceed the range-wide average by a significant margin for 25 species, including eight imperiled species, if all pending scenic listing petitions are approved. We conclude that scenic rivers provide important conservation benefits to Virginia's freshwater fishes. We also note that our flexible, model-based process can be applied in other rivers and used to inform other types of freshwater conservation programs that seek to identify and protect the highest quality habitats.