Stream Crossing Impacts on Freshwater Fish Communities and in-Stream Habitat in West-Central Alberta: Implications for Management and Conservation

Research has shown negative impacts on fish populations via cumulative effects of natural resource development, particularly where resource roads intersect streams. In large portions of Alberta, Canada, large declines in the distribution and abundance of stream fishes has been documented in relation to the tremendous growth of development. Employing a comparative study design, we performed fish and habitat surveys at 33 sites above and below culverts, bridges and crossing-free reference sites during the summer of 2013 to assess the extent to which industrially installed road-stream crossings are affecting stream fish communities. Total average catch-per-unit-effort (CUE; p = 0.009, p < 0.001, respectively) – and species richness (p = 0.003, p = 0.07) – were lower at both bridge and culvert crossing sites compared to reference sites. PCA analysis suggests culverted stream-crossings altered habitat features including pool/riffle/run percentages, substrate composition, and turbidity. Our findings highlight the importance of habitat connectivity in maintaining stream fish populations and support the conclusion that differences in local species richness and abundances can be an effective indicator of the extent to which stream crossings affect fish movement. Moreover, our results contribute essential data needed to assist in the prioritization of stream-crossing improvements and future planning decisions.