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Something’s killing coho salmon in Seattle, and car tires are a prime suspect

Published on October 16, 2018

Water running through creek
Image Credit: Wikimedia commons: CC BY-SA 3.0: Finetooth

When autumn rains return to western Washington, so do coho salmon. But in many of the creeks they swim up, something in the water leaves fishes gasping for air. They die quickly, before they manage to spawn. A new study points at chemicals from tiny bits of car tires as a prime suspect in the fishes’ untimely deaths. Most cohos that come to Miller Creek, in the leafy Seattle suburb of Normandy Park, die prematurely.

On a sunny September morning, researcher and Associate Professor in the College of Civil and Environmental Engineering Ed Kolodziej from the University of Washington spotted a dozen young cohos, each about two inches long, darting in and out of the shadows on Miller Creek. Their two-foot-long elders were likely just offshore, waiting for rains to raise the creek and creeks like it all around Puget Sound.

Virtually every coastal stream in Washington where water flows year-round is home to coho salmon. But those rains also help send a toxic stew into urban and suburban creeks around the sound. “Stormwater flows actually kill these coho salmon before they have a chance to reproduce,” Kolodziej said.

Heavy rains carry a chemical cocktail of motor oil, wiper fluid, brake dust and other gunk from roads and driveways into nearby drains, creeks and eventually Puget Sound. Stormwater runoff from highways and roads is the largest source of toxic chemicals in the sound, according to the Puget Sound Partnership.

Continue reading at KUOW News

Originally posted on KUOW News by John Ryan
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