Monday December 6, 2021

South Seattle Emerald

Every year, salmon journey from the open waters of the North Pacific, pass through estuaries along the coast, and swim upriver to spawn in the freshwater streams and creeks in which they were born. Yet across the western coast of North America, coho salmon are dying in large numbers as they return to urban watersheds. In West Seattle, a team of citizen scientists are surveying salmon to understand how many are affected.

Since 2015, small teams of volunteers have gone out every day in the fall to document returning salmon along a quarter mile stretch of Longfellow Creek.

The study, which is coordinated by the environmental nonprofit Puget Soundkeeper Alliance, is modeled after similar publicly funded studies run by the City of Seattle and the National Oceanic and Atmospheric Administration between 1999 and 2005. As Puget Soundkeeper Alliance’s Gillian Flippo explains, “The salmon are uniquely affected by the stormwater … causing them to die before they spawn.” It’s a phenomenon that researchers are calling “pre-spawn mortality” or “Urban Runoff Mortality Syndrome.” All told, the surveys show that each year between 50% and 80% of returning coho are dying from exposure to urban waters.


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