A new University of Washington study confirms that chemicals from car tires turns streams toxic and is proving deadly to Pacific Northwest coho salmon returning to spawn in those waters. The findings show that 6PPD-quinone — a highly toxic oxidation product of tire rubber particles — turns streams toxic and may be responsible for the annual die-offs observed among migrating adult salmon across the Pacific Northwest. Researchers say such regular acute mortality events, mostly in urbanized watersheds, is estimated to kill 40 percent to 90 percent of returning salmon before they have a chance to spawn.
Retrospective analysis also suggests that this deadly compound is widespread in stormwater-impacted waterways across the West Coast of the United States.
UW associate professor Edward Kolodziej notes that anecdotal reports of urban stormwater killing coho salmon first occurred in the 1980s in Bellingham, Washington. This occurrence was documented around Seattle in the 2000s by Nat Scholz and others at NOAA’s Montalke laboratory, “but as far as I know, nobody has really paid attention to possible coho sensitivity to stormwater and roadway runoff elsewhere,” he said.
Jenifer McIntyre, an assistant professor at Washington State
University’s School of the Environment in Puyallup, said that by dying in droves in urban streams, coho salmon have let researchers know that they are incredibly sensitive to something in stormwater runoff.
“Decades of research by NOAA Fisheries, U.S. Fish and Wildlife Service and UW has confirmed that roadway runoff contains the ‘something’ in stormwater runoff, and that tires are the most likely source,” McIntyre said. “Now that we have identified the chemical driving that toxicity in coho salmon we are starting to investigate the sensitivity of other aquatic animals to this toxicant,” she said. Researchers know that coho salmon are more sensitive to stormwater than many other species they have studied, but they have yet to determine whether this is directly related to their sensitivity to 6PPD-quinone, and they still don’t know the vulnerability of other aquatic life to this newly discovered contaminant.