Walleye continue to move upstream, pose threat to native salmon and steelhead

Anglers in the lower Snake and Salmon rivers encountered more walleye so far this year than they did in 2023, indicating an increased presence by the nonnative predatory fish that pose a threat to wild salmon and steelhead.

According to the Idaho Department of Fish and Game, it tallied more than 60 verified reports of anglers catching walleye in the two rivers this year. That compares to 19 verified reports in 2023.

“The increase is likely due to increasing abundances of walleye and our efforts to reach out to anglers about walleye,” the agency said in a news release.

Walleye were first documented upstream of Lower Granite Dam on the Snake River in 2016. But the fish, which are popular with many anglers as table fare, have been in the Columbia River system for decades. They were likely illegally introduced into Lake Roosevelt above Grand Coulee Dam about 80 years ago. From there, they moved down the Columbia, likely helped by more illegal introductions, and then started pushing up the Snake. Lyons Ferry, downstream of Little Goose Dam, has become a destination spot for walleye anglers in the region.

Like nonnative smallmouth bass and native northern pikeminnow, walleye prey on juvenile salmon and steelhead as they flush downstream to the Pacific Ocean each spring and summer. Fisheries managers believe abundant walleye populations in the Salmon River and the Snake River in Hells Canyon will pose a greater threat to salmon and steelhead than do populations in the lower and middle Columbia River and even the Snake River downstream of Lower Granite Dam. That is because the downstream populations only have access to salmon and steelhead smolts during their outmigration to the ocean.

Populations of walleye further upstream have access to juvenile salmon and steelhead not only during outmigration but also during the one or more years the young fish spend in freshwater.

Fisheries managers are asking anglers to keep any walleye they catch. There are no size or bag limits on walleye in areas where they overlap with salmon and steelhead.

“Thousands of anglers fish the Snake and Salmon rivers every year, and if they killed every walleye they caught it could slow their expansion,” the department said in its news release.

So far this year, walleye have been caught all the way up to Hells Canyon Dam on the Snake River and at Riggins on the Salmon River. They have ranged in size from 13 to 30 inches.

Anglers who catch walleye from the Snake or Salmon rivers are asked to report their catches to Idaho Department of Fish and Game regional wildlife biologist Marika Dobos at marika.dobos@idfg.idaho.gov, or (208) 750-4228.