Idaho sockeye returns improving, but face an uncertain future

It’s a good news/bad news thing. Idaho’s sockeye returns are improving, and about 90 adults have returned to the Stanley area this summer. This year’s total is already the sixth-highest sockeye return to Idaho since the early 1980s, according to Idaho Fish and Game statistics, and more have been counted at Lower Granite Dam on the Snake River that are headed to Stanley. Between 1999 and 2010, 3,193 mostly hatchery-produced adult, sockeye returned to the Sawtooth Valley.

Since 1991, Idaho’s sockeye have been listed as endangered under the Endangered Species Act, and Idaho sockeye nearly became extinct in the 1990s. Between 1991 and 1998, only 16 wild sockeye returned. But in 2010 a modern “record” 1,355 returned to Stanley. Thousands of sockeye returned annually in the early 20th century before dams were constructed on the rivers.

Idaho’s sockeye are the southernmost population of their species and have to swim 900 miles up the Columbia, Snake and Salmon rivers to reach the lakes in the Stanley basin. Most are the product of the Eagle hatchery where adults are spawned and young fish raised. Future runs could improve with help from a new hatchery in Eastern Idaho that comes online next month that will boost production from about 200,000 sockeye smolts to more than a million.

But here’s the “but.” Hotter summer weather like we’ve experienced in recent years boosts temperatures in the Columbia, Snake and Salmon rivers, which can be lethal to adult fish. When the rivers are around 70-degrees, the number of fish crossing Lower Granite Dam and completing their migration to Stanley declines, so more smolts released doesn’t necessarily equate to more adults returning if hotter summers persist.

Photo by Roger Phillips. Adult sockeye swim in tanks at the Eagle Hatchery, where they are spawned and smolts raised to be released into the wild.

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