Case Study of Impacts of Highway Culverts on Salmon and Steelhead

The salmonids, salmon and trout, are economically and socially important fishes that require consideration and protection when roads are constructed and maintained within their ranges. Over the courses of their lives both resident and anadromous salmonids require a variety of aquatic habitats. It is well established that that these fishes need to have efficient access among streams in addition to efficient access to different habitats within streams to maintain viable populations. Barriers may either physically block movement or impose excessive energy costs on movement, thereby preventing or seriously impeding access to necessary habitats and affecting population sizes. Insuring fish passage at highway stream crossings is a key component of salmonid conservation and restoration efforts. Thus, the identification, prioritization, and treatment of migration barriers is a vital step towards recovering salmonid populations by restoring ecological connectivity.