Scientists discover possible cause of widespread salmon death

Salmon of the West Coast have died suddenly and mysteriously — Scientists finally know why.
A team led by researchers at the University of Washington Tacoma, UW and Washington State University Puyallup have discovered a chemical that kills coho salmon in urban streams before the fish can spawn. Shown here Jenifer McIntyre (left), an assistant professor at WSU School of the Environment in Puyallup; Edward Kolodziej (center), an associate professor in both the UW Tacoma Division of Sciences & Mathematics and the UW Department of Civil & Environmental Engineering; and Zhenyu Tian (right), a research scientist at the Center for Urban Waters at UW Tacoma; and are at Longfellow Creek, an urban creek in the Seattle area. (Photo by Mark Stone/University of Washington)

Over the years, salmon of the Pacific Northwest have begun to die at alarming rates. After years of intensive research, scientists have a lead on this puzzling case and it’s probably not what you expected.


New studies reported by CNN indicate that salmon are dying off due to chemicals used on tires. A chemical antioxidant called 6PPD is used to improve the lifespan of your tires, but it cuts the lifespan of native salmon short.

Over time, 6PPD reacts with the ozone to create an entirely new chemical byproduct called 6PPD-quinone. It’s carried via runoff to natural bodies of water that these fish inhibit, effectively slashing the lifespan of nearby salmon. The species of salmon that this impacts most regularly is the traditional coho salmon, which has a large population in Washington state.

The findings were published by an esteemed research team here.

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The study’s lead investigator, Ed Kolodziej, made a statement published by CNN: “We believe that 6PPD-quinone is the primary causal toxicant for these observations of coho salmon mortality in the field,” Kolodziej said. “It’s exciting to start to understand what is happening because that starts to allow us to manage these problems more effectively.”

Coho salmon span the West Coast of the United States, residing in Washington, Oregon California and reaching as far as Alaska. They are one of the five species of salmon that reside in the Pacific Northwest. Kolodziej noted that the presence of coho salmon is a strong indicator of a healthy natural ecosystem.

Now, researchers must shift focus toward fixing the issue before it’s too late. In central California, the coho population has died at alarming rates. In that region, they’re considered “threatened” by the US Fish and Wildlife Service’s Endangered Species Act.

Kolodziej himself is a representative of the University of Washington. He’s an associate professor of civil and environmental engineering at the state’s esteemed University. He also credits Zhenyu Tian, the lead study author and a research scientist at the University of Washington-Tacoma, for his efforts. Aquatic toxicologist Jen McIntyre of Washington State University is a co-author of the study as well.

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