Taking a Leap of Faith: Assessing the Passability of Fish Through Road Culverts

Habitat connectivity has one of the most significant effects on the persistence and/or recovery of aquatic species. The modification of stream barriers is a critical step towards the reconnection of movement corridors for fish species. One important aspect in the improvement of stream barriers is an understanding of how barriers affect the movement of fishes. Multiple models have been developed to assess the passsability of stream barriers. Although these models appear to be theoretically sound, relatively few have been validated with in situ observations. Using an antenna array at 5 culvert locations with adjacent downstream control sites, we analyzed a number of stream barrier metrics commonly used in determining passability coefficients. The results of this study will assist managers in accurately assigning stream barrier thresholds which in turn will provide more accurate information to inform decision makers about restoration scenarios.