Contaminants found in juvenile chinook salmon along Fraser River, researchers find

Pharmaceuticals and flame retardants are among dozens of chemicals researchers found in juvenile chinook salmon living in the Fraser River estuary.

Researchers collected samples from hundreds of fish between 2019 and 2021, detecting more than 80 contaminants in the salmon tissue alone — the source is believed to be industrial and wastewater sites upstream. The team also studied water samples from salmon habitat, detecting 130 contaminants.

The research team expects the chemicals could be having negative effects on chinook growth, behaviour and their overall health.

"A lot of the stuff that goes into our wastewater goes into our fish," said David Scott, the lower Fraser research and restoration director for the Raincoast Conservation Foundation (RCF).

"We found a whole variety of pollutants from pharmaceuticals and personal care products to pesticides and flame retardants," he said.

The team monitored Harrison River chinook stock that develop in the Fraser River estuary, sampling their tissue and habitat at multiple sites.

According to the study, 16 of the chemicals uncovered were considered “priority” contaminants with the potential for adverse effects, including organic chemicals and pharmaceuticals. The flame retardant, PBDE-penta-total, was the lone priority contaminant found in salmon tissue samples. The other 15, including cocaine, and pesticides, were found in habitat water samples.

Eight additional "watchlist" chemicals, the presence of which corresponds to elevated biological risks, were found in salmon tissue samples. That included pesticides, pharmaceuticals and other organic chemicals.

The study was largely financed by the Department of Fisheries and Oceans, and done in conjunction with the RCF and Simon Fraser University.

Tanya Brown, study co-author and assistant professor at Simon Fraser University's department of biological sciences, said there are likely more chemicals the fish are being exposed to that wasn't screened for in the research, which focused on organic chemicals.

She said the combination of the various chemicals the fish are exposed to is alarming.

"There's over 30,000 high-volume use chemicals on our marketplace, many of which we can't even measure," said Brown. "There's likely a much larger list that warrant concern and additional monitoring here."

Similar work has been done in Washington state's Puget Sound, where researchers have tracked contaminants in fish habitat for more than 30 years.

Molly Shuman-Goodier, a research scientist with the Washington Department of Fish and Wildlife, said lab work has shown that the synthetic organic chemicals inhibit chinook growth.

"There's evidence this is likely happening, but we're trying to document it in the field," said Shuman-Goodier.

Shuman-Goodier said there could be potential long-term impacts.

"The research shows that that's the life stage where growth is really important, and if we don't grow fast enough, it influences return rates," she said.

And then there's what happens further up the food chain.

"These chinook salmon that we're capturing here, they go out to the ocean, they get big, and then they get eaten by southern resident killer whales," said Scott.

"Southern resident killer whales have some of the highest contaminant loads of any marine mammals we see."

Humans also eat chinook, and the organic chemical loads found in Puget Sound chinook exceeded the human health threshold set by the Washington State Department of Health.

Scientists on both sides of the border said the research could inform how chemicals are managed, whether it's through public policies, or even individual choices.

"We did detect a number of pharmaceuticals that were high on our priority list," said Brown. "Just being mindful of how we dispose of our pharmaceuticals is something we can do on an individual level."