Floodgates protect areas from flooding by controlling when water can pass through dikes but also might interfere with habitat connectivity for fish like salmon. A new study by Rebecca Seifert and Jonathan Moore, published in the journal of Estuaries and Coasts, provides insight into challenges and opportunities for balancing flood protection and fish habitat in the Fraser. 

 

Across more than 20 sites in the lower Fraser River, Seifert used time-lapse photography to document how often floodgates were open and closed and how this impacted fish. 

 

She discovered there was a huge range in how often these floodgates opened--some opened daily, while others were almost always closed. For those waterways that had floodgates open more often, there was higher native fish biodiversity and better oxygen levels. 

 

This study indicates that floodgates designed to open more frequently can benefit native fish, including salmon. The environmental NGO Watershed Watch Salmon Society is calling for municipalities to work towards fish-friendly flood protection. 

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