The chemical killing Cowichan coho comes off your tires

Qutxulenuhw Tim Kulchyski got the call at 6 a.m. On the line was Elder Siilh'na'mut Ken Elliott, who'd been restoring habitat near Duncan's sewage lagoons and followed a racket of crows and kingfishers to the water. What he found was thousands of juvenile coho on their sides, swimming in circles with their mouths wide open.

That was June 2007. Elliott drove to dry cleaners, car washes and gas stations that afternoon, convinced someone had dumped something toxic after the heavy rain. He found nothing. A fishery officer traced the dead fish to a spot right beside a storm drain.

The answer took thirteen more years, and it came from researchers across the water in Puget Sound. In 2020 they identified 6PPD-quinone, a compound that forms when 6PPD, a preservative that keeps tire rubber from cracking, breaks down in sunlight. Every car sheds a little rubber onto the road. When it rains, it washes into salmon habitat, and it can kill coho in hours at tiny concentrations.

Kulchyski now has no doubt that's what killed the fish in Fish Gut Alley, and he's pushing to make the scale of the problem understood. First Nations, he says, are on the front lines of dealing with it.