The Role of Riparian Vegetation and Instream Habitat on Fish Communities in Intermediate-Sized Arizona Rivers
June 2016 - December 2018
The native fish populations of the southwest United States are highly endangered and drastically declining due to multiple anthropogenic stressors. Physical habitat has been defined through habitat suitability criteria (HSC) for these vulnerable populations yet has been primarily limited to depth, flow, and substrate. The relationship between riparian vegetation and instream habitat on fish communities in the arid southwest United States is uncertain. The relationship needs to be assessed in order to implement management practices to conserve fish populations of interest. Four streams within central Arizona (Verde River, Blue River, San Francisco River, Tonto Creek) were selected based on high priority. Over 1,200 sites, throughout the streams, were sampled using pre-positioned electrofishing devices during the 2017 summer low-flow period to identify relationships among fish presence and riparian and instream habitat variables (overhead canopy, bank stability, bank vegetation type, grazing pressure, presence of undercut banks and overhanging vegetation, and percentage of aquatic vegetation and large woody debris) using both in-stream measurements and ArcGIS. Currently, logistic regression models are being constructed for these habitat variables on the presence of several fish species. This research will allow agencies in the arid southwestern United States to better manage riparian areas to benefit fish populations accordingly. Field work and data analysis are underway for this project, and results will be presented in a publication and a thesis. Partners include USFS and USFWS.