A B.C. conservation group believes a common chemical found in car tires is responsible for the death of dozens of salmon in a North Shore creek.
The West Vancouver Streamkeepers says student volunteers monitoring Brothers Creek recently discovered at least 30 dead coho salmon, shortly after heavy rainfalls.
Streamkeepers former president John Barker said the group contacted Fisheries and Oceans Canada (DFO), and believes the chemical 6PDD quinone, used to prevent tires from cracking, is likely responsible for the deaths.
“The indicators are that that’s where it’s come from,” he said.
Automobile tires that break down, it sits up on the roadways in the summer, and then with the influence of sunshine the toxicity is really elevated, and then believe it or not it can run off into the stream and just annihilate coho.”
Other salmon species in the stream appeared to be unaffected, he said, which is also consistent with the chemical being much less toxic to other salmonids.
Within a short period of time, other coho returning to the stream appeared to be unaffected, he added, suggesting the chemical was washed into the waterway by recent rains.
“It was like a plume or a flush came through and took these fish out,” he said. “The following week, absolutely amazing … the last team to survey on week three had 27 fish, and 15 were coho, all alive and all healthy.”
DFO research scientist Tanya Brown said Brothers Creek is one of several waterways the agency is monitoring in Metro Vancouver for 6PDD quinone.
Researchers have been taking water samples before, during and after rain events in order to test for surges of the chemical, she said.
While the results aren’t back yet, Brown said research elsewhere in the region suggests it could “very well have led to die offs.”
“From the work we have been doing over the last two and a half years for all of our Metro Vancouver sites … our average levels at all of our Metro Vancouver sites at various creeks exceed levels that where we would expect lethality in coho salmon,” she said.
“From the time we go out before to during a rain event we are seeing up to a 90-fold increase in 6PPD quinone concentrations, and those levels are at levels where we are expecting to see lethality.
Brown described the consistently high levels of the chemical in local waterways during rain events as “very concerning,” adding that DFO had scheduled a meeting with the West Vancouver Streamkeepers next week to discuss the issue.
Barker said he believes the chemical is present in all major tire manufacturers’ product, leaving consumers with little they can do.
But he said he’d like to see municipalities building more bioswales — landscape features that soak up polluted runoff and use earth and vegetation to filter it out — ear sensitive waterways.
“It’s sitting on the roadways, it’s had its effects from the oxygen, it’s terribly toxic,” he said of 6PPD quinone.
“As soon as you get a rainfall that’s either going to find a catch basin or come over the hillside and enter the streams.”
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