Evaluating the effects of flood proofing barriers on fish communities in urban streams

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David investigated the effects on fish communities related to structural flood proofing barriers commonly used to control flows between the lower Fraser River and its tributaries. Anadromous fish species, like salmon, require the ability to move between freshwater and marine habitats to complete their life cycles. Flood proofing structures may inhibit this movement. In particular they may prevent juvenile salmon from migrating out from their natal streams and prevent some species, such as Chinook salmon, from accessing non-natal rearing areas before they migrate out to sea. Flood proofing barriers also cause water to become stagnant and may be associated with oxygen-depleted “dead zones”. To investigate this, he repeatedly sampled fish communities in tributaries of the lower Fraser River at five barrier sites and five reference sites throughout the summer of 2013. His findings inform managers on the potential trade-offs associated with installing flood–proofing barriers; information that is pertinent with the increasing need for these structures due to predicted climate change induced future sea-level rise.   

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Current Position: Research Biologist, Raincoast Conservation Foundation, Vancouver