Why are Salmon Dying? Chemicals from Tires in Highway Runoff Rainwater Explain Why 90% of Coho Salmon Mysterious Die Each Year

Coho salmon keep dying in streams of Washington state every year.
Study by university scientists has discovered the cause of these fish deaths.
Car Tire chemicals in waterways causing mass die-off of Salmon on West Coast.
Study has found one added highly toxic chemical in old tires is deadly to salmon.
Chemicals washed off roads is found on every single nearby spawning streams.
Stormwater containing the chemical Y exposure causes acute mortality.
Deaths occur when salmon migrate to urban creeks to reproduce.
Salmon are experiencing a serious threat somewhere in their native range.

New study found that runoff for rain water carries fragments of old tires from road surfaces.
Preservative substance in car tires, 6PPD, is toxic chemical responsible.
Salmon, other fish, & other creatures in the U.S. also at risk from the car tire chemical.
Chemical is highly toxic quinone transformation product of N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine) (6PPD),

Filtering storm water through soil is relatively ineffective.
Installing infiltration basins to treat road runoff before spawning streams tried.
But filtering process is very expensive & labor intensive.
Cohu salmon is on federal lists of threatened or endangered fish along test Coast.
This one species of salmon facing threats from dams, polluting & climate crisis.
To save Salmon, Federal agents granted permission to cull sea lions along  Columbia River basin.
Desperate attempt to save declining numbers of Chinook and sockeye salmon.
One potentially problematic solution for reducing tire-shedding involves changing the texture of pavement.
No agency or official has apparently called for the discontinued use of 6PPD.

 “The more we look, the more we find it. In some years all of the fish we find dead did not spawn.” –
— Jenifer McIntyre, an assistant professor of aquatic toxicology at Washington State University.

90 percent of coho salmon are lost every year.


1)     Pollution from car tires is killing off salmon on US west coast, study finds –https://www.theguardian.com/environment/2020/dec/03/coho-salmon-pollution-car-tires-die-off#:~:text=Pollution%20from%20car%20tires%20that,state%20were%20dying%20before%20spawning.

2)    How Scientists Tracked Down a Mass Killer (of Salmon – https://www.nytimes.com/2020/12/03/climate/salmon-kill-washington.html

3) A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon –https://science.sciencemag.org/content/early/2020/12/02/science.abd6951

4)  Science  04 Dec 2020:
Vol. 370, Issue 6521, pp. 1145

5) LA TIMES, December 4 Issue, “Chemical From Car Tires Killed Salmon”


Erik Stokstad  Science Magazine Journalist [Wrote article)
Edward Kolodziej, an associate professor at the University of Washington.
Jenifer McIntyre, assistant professor, aquatic toxicology, Washington State U.
Mariska Obedzinski, California Ses Grant Fisheries Biologist
Peter Moyle, UC Davis Professor
Rebecca Sutton, Co Author of the Study
Joe Dillon, Water Quality, NOAA Fisheries
Matt St. John, California Water Quality Control Board

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