Construction of a nature-like fishway past the Big Bar landslide, March 2021. (B.C. government)

Construction of a nature-like fishway past the Big Bar landslide, March 2021. (B.C. government)

Salmon getting through B.C.’s Big Bar landslide, runs rebounding

Early Stuart sockeye run expected near average after low years

Three years of work to allow salmon to migrate up the Fraser River past the Big Bar landslide is paying off, but warm and low water continue to affect the runs, the Pacific Salmon Commission says.

“All salmon arriving at Big Bar seem to be able to pass the slide using the nature-like fishway and there is no delay in the upstream salmon migration,” the commission said in its latest report July 23. “As of July 17, a total of 22,821 salmon have been detected at the Churn Creek telemetry site 40 km upstream of Big Bar. Sockeye stocks with spawning grounds in the watershed upstream of the rockslide need about 10 days to migrate from the Lower Fraser River to the rockslide location.”

Sonar images upstream and downstream of Big Bar, in the Fraser Canyon north of Lillooet, show chinook and sockeye passing the slide, which took place in 2018, dropping 75,000 cubic metres of rock into the river and blocking migrating salmon routes. Trucks and a “salmon cannon” were deployed to get fish past the blockage. Blasting and heavy equipment were used when conditions allowed to tackle the slide, and the fishway was constructed early this year.

Commercial salmon fisheries remain closed, after the commission’s Fraser River panel said catches remained low in marine test fisheries conducted this week. An estimated 76,300 sockeye have passed the acoustic monitoring site at Mission this season.

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The Early Stuart sockeye run has mostly entered the river, and the panel has upgraded its forecast with an in-season run size of 65,000.

“This would imply close to average productivity, instead of the very low productivity Early Stuart and other Fraser sockeye stocks have experienced in recent years,” the panel reported Friday. “The resulting run size is still very low compared to other years on this cycle line and substantially below the run size needed to achieve the escapement target of 108,000 which would trigger consideration of directed fisheries.”

Readings taken July 22 showed the Fraser River flow rate at Hope was approximately 23 per cent lower than average for that date, with water temperature 1.2 degrees higher than average.


@tomfletcherbc
tfletcher@blackpress.ca

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Fraser Riversalmon stocks