GIS tools to assess the risks and benefits of barrier removal to native fish populations in Idaho

Removing fish passage barriers is a strategy for improving native fish habitat, however it can favor the spread of invasive species and pathogens.  In this study, we developed a framework to assess the risks and benefits of barrier removal to native fish species using GIS tools and statistical models.  The framework combines landscape- and local-level approaches in two phases: (1) delineation of habitat characteristics of invasive brook trout, New Zealand mudsnails and tubificid annelids (host of whirling disease parasite) and (2) spatial analysis of stream network connectivity.  We used GIS to derive habitat requirements such as stream channel slope, contributing area, stream temperature, percentage agriculture and spreading vectors such as angler access to streams.  We prioritized barriers to increase suitable habitat for native species while minimizing risk of spread of invasive species.  We used the Upper Boise River Basin in Southwestern Idaho as a case study to evaluate bull trout habitat.  We provide a Spatial Decision Support System (SDSS) to use this approach in other mountainous watersheds.