Research Document 2020/049

Review of information to guide the identification of Critical Habitat in the riparian zone for listed freshwater fishes and mussels

By Caskenette, A.L., Durhack, T.C., and Enders, E.C

Abstract

Fisheries and Oceans Canada’s Species at Risk Program provides protection of the habitat necessary for the survival or recovery of listed freshwater fishes and mussels. It is well documented that the riparian zone is essential for the maintenance of freshwater aquatic habitats, fishes, and mussels. Despite this extensive body of literature, riparian features are not consistently included as Critical Habitat for listed freshwater fishes and mussels. An evidence based approach was required to guide the identification of features in the riparian zone as Critical Habitat. Riparian Critical Habitat are riparian features that: maintain the quality of aquatic features identified as Critical Habitat, and are directly used by fishes and mussels. We performed a literature review to determine the relevant riparian features, and the processes by which they affect aquatic features and water quality attributes. From these literature reviews we identified seven main processes by which riparian features affect aquatic features and water quality attributes: erosion, filtration, infiltration, isolation, meandering, shading, and subsidization. In addition, we identified riparian features that may directly support freshwater fishes and mussels’ functions depending on their life history. Meta-analyses, reviews, and primary research articles were assessed to provide some guidance on the extent of riparian habitat required to support these seven processes. We outlined the current state of the literature regarding the extent of habitat required, and denoted where more empirical evidence is required. The dependencies of each process on attributes of the floodplain and other important considerations were summarised and can be consulted to determine what riparian features should be protected as Critical Habitat for a listed species. We have included additional resources to aid in the application of this guidance when defining the geographical area to be protected. Finally, five case-studies were used to provide an example of how practitioners may apply the guidance provided here to determine riparian Critical Habitat for a listed species.

Research Document 2020/049 (PDF, 2,144 KB)

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