Columbia River Wild Sockeye Salmon Run Spikes, But Record Water Temps May Block Them From Spawning Grounds

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In the meantime, fisheries managers, tribal leaders, state officials and environmentalists are cheering the unexpectedly large run of sockeye this month. "We're in the middle of a record sockeye migration with respect to the Columbia River population of sockeye," said Miles Johnson, legal director at Columbia Riverkeeper. "That's a huge recovery story.” The sockeye resurgence is of wild fish, separate from hatchery breeding, Johnson said. "It's a testament to what these fish are capable of when we give them a chance,” he added.

Chad Jackson, a fish program manager in the Washington Department of Fish and Wildlife, described the event as a “bit of a perfect storm,” attributing the large number of fish to a successful outward bound migration and survival rates in the ocean. That success, however, must still survive the unusually warm temperatures in the Columbia River Basin’s tributaries. The problem is what scientists call a “thermal barrier,” which marks the point at which the water temperature becomes too warm for the fish to continue their journey — typically over 68 degrees during both day and night.

It’s found where the Columbia River meets the Okanogan River, which travels north into Canada and is reliant on snowpack and prone to low flows and high temperatures. The salmon will typically halt their upstream travels at this point in Brewster, Washington, while waiting for the water temperature to drop back to an acceptable level allowing them to move on. Biologists in the region warn the thermal barrier — which occurs annually — is starting earlier and expected to last longer than usual.

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Although temperatures in portions of the Columbia River Basin have spiked in previous years — an early heat wave in 2015 trapped fish in the Lower Columbia River, resulting in a major die-off, and temperatures in 2021 achieved levels similar to this season — salmon populations have never been physically relocated across the thermal barrier at the Okanogan River. "People are asking the question, people are thinking about it, but logistically there are a lot of steps and a lot of things to contend with," Jackson said. "It's not as simple as — pull some fish out of the river and truck them into Canada."

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https://www.eenews.net/articles/record-salmon-migration-runs-into-hot-water/