Threats and Opportunities for Fish Habitat Connectivity Conservation in the Missouri River Basin At Multiple Scales

Dependent relationships between fish population persistence and habitat connectivity highlight the importance of understanding broad-scale patterns responsible for local community composition and set the stage for prioritizing conservation opportunity areas in which habitat connectivity might be maintained or restored. However, identifying appropriate spatial scales at which conservation actions might be most effective is challenging because of variability in fish habitat needs among species. In this study, we focus on the spatial distribution of barriers (road-stream crossings and dams) and native fishes among streams of various size (small streams to large rivers) in the Missouri River Basin and relate these distributions to species imperilment. We also use a systematic conservation planning approach to demonstrate the sensitivity of conservation solutions to management scale (e.g., state, hydrologic units, entire basin) by considering which fish species stand to gain the most by approaches at each scale. We found that barriers and native species were not distributed equally across stream sizes and that imperiled species such as large-river specialists would benefit most from conservation approaches implemented at the largest planning scale (Missouri River Basin). Our study highlights cost-effective management approaches that increase cooperation between states and tribes in the Missouri River Basin with the ultimate goal of enhancing protection of fish biodiversity.