Fishing for the Big Picture: Aquatic Habitat Representation at Large Spatial Scales

Abstract:

Rivers are often altered to meet human needs, although water development degrades and fragments aquatic habitat, threatening fish and other organisms. Simple and generalizable methods to identify suitable aquatic habitat across large spatial scales are needed to inform conservation planning and water resource management. Habitat suitability models offer a solution, but existing approaches are difficult to apply at large spatial scales or lack ecological relevance. We used publicly available GIS and remotely-sensed data to estimate aquatic habitat conditions and model monthly habitat suitability for Bonneville Cutthroat Trout and Bluehead Sucker in Utah. We validated aquatic habitat estimates, then compared habitat suitability model accuracy using species presence data. We quantified habitat fragmentation using the dendritic connectivity index, and compared barrier-only connectivity to connectivity including barriers and habitat suitability. Aquatic habitat conditions and habitat suitability estimates were accurate at the statewide scale. Results indicate that simple habitat suitability models using few variables best predicted habitat suitability for both species. Utah stream networks are highly fragmented by instream barriers, and seasonally unsuitable habitat caused additional fragmentation. Findings from this research inform conservation and water resource management, and identify promising habitat protection and restoration locations to conserve aquatic species. The modeling approach is generalized for different species and suitable for large spatial scales, expanding current methods for quantifying aquatic habitat.