Walleye Moving Up The Snake Past Lower Granite Dam

You won’t find it on the Fish Passage Center or Columbia River DART websites, but another species is now being counted at a Snake River dam: walleye.

Idaho fishery managers report an “increasing number” are showing up at Lower Granite, with 2022 expected to see the highest annual tally yet.

Even more alarming is that walleye may be colonizing the Gem State’s fabled salmon and steelhead streams.

IDFG reports “Anglers are encountering walleye in Idaho’s anadromous waters with increasing frequency,” including one fish that was caught in Riggins, 80 miles up the Salmon River, which flows into the Snake in Hells Canyon.

The news is unwelcome on both sides of the state line.

“I’ll be brief: No matter how you slice it, it’s bad for salmon and steelhead,” said Chris Donley, the Washington Department of Fish and Wildlife fisheries manager for far Eastern Washington’s Region 1.

Nolan Smith, an Idaho Department of Fish and Game fisheries technician, terms walleye “effective and opportunistic predators that will prey on emigrating salmon and steelhead smolts” that are already subject to the jaws of a host of native and nonnative fish, birds and pinnipeds. He says that research done elsewhere in the Columbia-Snake system found an average walleye will eat 2.5 smolts a day in spring, as the young Chinook, coho, steelhead and sockeye move downstream to the Pacific.

It’s believed that walleye, a popular game fish originally from the Upper Midwest, were illegally transplanted into Northeast Washington’s Lake Roosevelt or thereabouts in the 1960s, and they’ve since spread throughout much of the Columbia Basin and well downstream. This season, three were turned in by Northern Pikeminnow Sport-Reward Program anglers at the Rainier, Oregon, station, across the big river from Longview, Washington.

To be clear, at the moment Lower Granite walleye counts are nowhere close to those seen during spring Chinook and summer steelhead runs – or even struggling sockeye, for that matter.

IDFG estimates that 2020 saw 160 swim through the dam’s fish ladder and into the Snake’s Lake Lower Granite and another 45 were trapped and removed there, while last year saw 294 and 75, respectively.

“We will run our expanded estimate at the end of the season, but the number of walleye that have been trapped so far in 2022 suggests that we are slightly ahead of pace relative to 2021,” states Smith.

He says that annually, roughly 20 percent of fish that enter the ladder are trapped.

Walleye trapped in 2016 – the first year they were apparently observed at Lower Granite – as well as 2017, 2018 and 2019 were released back into the Snake below the dam.

Since 2020, trapped walleye have been lethally sampled “to better understand things like age, growth, maturity and diet,” says Smith.

He reports that the average Lower Granite walleye runs just under 18 inches and 2 pounds, but the largest sampled so far went 23 inches and 4.5 pounds.

Well upstream of there, pikeminnow program data from this season shows that two were turned in at the Greenbelt boat ramp in Clarkston and three at the Swallows Park launch halfway to Asotin. Prior years saw four reported at Swallows in 2021 and one at Greenbelt in 2018, when managers started detailing weekly game fish catches.

As for how that one walleye got all the way up the Snake and Salmon to Riggins, my immediate assumption was a @$%@$ bucket biologist had caught it elsewhere and dumped it into the wilderness river, but that’s not what IDFG honchoes believe.

“Although walleye are not known to be the dynamic swimmers like salmon, they have been found to swim hundreds of miles in large lakes in a matter of a couple months. They will also migrate up rivers during their spawning migrations of over 100 miles,” states Joe Dupont, the Clearwater Region fisheries manager.

“So, swimming from Lower Granite Dam to Riggins over multiple years would not be considered an outlandish feat for a walleye. People who illegally move walleye usually target lakes where they could potentially flourish. For those reasons, it is most likely that the fish caught by Riggins migrated there on its own accord,” Dupont adds.

Smith points out that there no restrictions on walleye harvest in Idaho’s Snake, Clearwater and Salmon and the fish “make tremendous table fare!”

“So, if you happen to find one at the end of your line, we encourage you to keep it and enjoy your meal,” he advises.