Improved fishway, lower river flow raise salmon migration hopes at B.C. rock slide

Workers are seen on the cliff at the site of a massive rock slide on the Fraser River near Big Bar, west of Clinton, B.C., on Wednesday July 24, 2019. THE CANADIAN PRESS/Darryl Dyck

VANCOUVER _ Fisheries officials say they expect thousands of migrating salmon will be able to pass through an area where a massive rock slide has impeded them on British Columbia’s Fraser River after structural changes to a waterway and anticipated lower river flows.

They told a news conference Wednesday they are confident the improvements over the past two years at the Big Bar slide north of Lillooet will allow more salmon to reach their spawning grounds this year.

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Michael Crowe of Fisheries and Oceans Canada said chinook salmon are strong swimmers and are expected to make it through the slide zone without many problems, but early arrivals of sockeye salmon remain vulnerable in high waters.

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He said since the rock slide, a protected route to help salmon navigate the slide zone has been built, and a separate fish ladder has been constructed where salmon will be put in tanks and trucked to a calm area past the slide.

“We know the restoration efforts to date are working because we have better passage conditions than we’ve had in the past,” he said. “This year is better than last year and last year is better than 2019, so our work is progressing and is successful.”

Read more: Salmon expected to start arriving soon at Fraser River landslide: DFO

Crowe said they have hope that the nature-like fishway will manage most of the salmon trying to get through the slide area, particularly the late-arriving large runs.

“The particular populations that are in the hundreds of thousands, and collectively the more than one million we expect to see this summer.”

However, the future concern is ensuring the area allows salmon to continue to pass through every year, including those seasons with high water levels, he said.

The fish way was constructed to be a protected, slower-moving path that guides salmon past the slide area and back on their way to the spawning grounds. Crowe said the rocks and boulders were placed on the fish way to create tiny back eddy resting areas for salmon.

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The rocks were also placed to reduce the thrust of the rushing river, making it easier for the salmon to get through, Crowe said.

The slide in a remote canyon of the Fraser River was discovered in June 2019. Over 85,000 cubic metres of rock sheared off the 125-metre-high cliff into the river, creating a five-metre waterfall that trapped the salmon below.

Since then, fisheries workers and other experts have been trying to ease the passage past the slide by trucking them, building a fishway, blasting away the rocks to widen the channel and even using the Whooshh Passage Portal System, also known as the fish cannon, to propel the salmon in a tube past the rockfall.

Read more: Plans underway for ‘salmon cannon’ to help fish clear B.C. landslide

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Fisheries officials told a House of Commons committee last summer the early Stuart sockeye and chinook runs were decimated because the fish couldn’t make it past the slide area.

Crowe said up to 18,000 early Stuart sockeye are expected in the coming weeks and up to one million sockeye are due to arrive later this summer.

This report by The Canadian Press was first published June 23, 2021.

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