Millions of cubic metres of mine waste escaped from a tailings pond Monday into local waterways near the town of Likely, B.C., raising alarm about harm to salmon spawning grounds.
"It could alter their senses, put them in a bit of disarray and stress them out," said Gord Sterritt, executive director of the Upper Fraser Fisheries Conservation Alliance.
"And they wouldn't be able to mate and get back to their spawning grounds," he added.
As of Tuesday night, the Department of Fisheries and Oceans banned salmon fishing in the Cariboo and Quesnel Rivers because of the Mount Polley mine spill.
Sterritt said he's been fielding calls from First Nations groups seeking advice on whether it's safe to eat the fish they've caught.
"The big question is we don't have any monitoring results on what actually has been released. We've seen what was in the pond and it's some pretty scary stuff," said Sterritt.
The conservationist said he's frustrated with the lack of information provided by officials.
"The water samples could have been processed much sooner."
Imperial Metals, owner of the mine, said the water quality report is expected Thursday.
Sterritt said the summer sockeye runs are just beginning to show up on the river, with a peak expected in the next three weeks.
"This is one year we were sort of counting on potentially upwards of three million for the run alone," he said.
"With the disaster, we're unsure."
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Craig Orr, the executive director of the Watershed Watch Salmon Society, has also received several calls from First Nations groups about how the spill will affect sockeye migration in the next few weeks.
"Quesnel Lake is a major summer sockeye producer in the Fraser River," he said.
Orr said salmon travel through the Horsefly River, Quesnel River and Mitchell River, all waterways potentially affected by the spill.
"We don't have a lot of those, there's only 24 lakes associated with sockeye in the entire Fraser and seven of those are listed in the red zone [depleted of fish]."
Orr said he's not just worried about the salmon.
"These fish feed the local wildlife," he added.
"I feel really badly for those folks there, it's gonna take a long time for the system to recover from this very major spill."