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NW Fishletter #391, March 4, 2019

[6] Walleye: Ravenous Salmon Predator Or Popular Sport Fish?

On one hand, walleye are a great catch--considered a delicious freshwater, white fish. On the other, they tend to dominate an ecosystem when they're not native. As an unwelcome transplant in the Snake and Columbia rivers, they gather at the mouths of tributaries and in pools below dams to gobble up young salmon and steelhead attempting to make the already treacherous journey to the ocean.

Fishery managers in Washington, Idaho and Montana have all been dealing with different forms of the walleye issue recently. They say the question of whether walleye are friend or foe depends on where you find them.

Walleye are not native anywhere in the Pacific Northwest. As one of the most popular sport fish in central northern states, they were brought here in the mid-1900s, and now populate many of the region's lakes, rivers and streams, including the Columbia and Snake rivers and many of their tributaries. They average 16 to 25 inches in length and weigh 2 to 12 pounds, but can grow much larger.

How they're managed depends on where they are.

At Lake Pend Oreille in Idaho's Panhandle, the Idaho Department of Fish and Game started a new reward program on March 1. Lucky fishermen now have a chance to catch one of 50 walleye injected with an internal tag and worth $1,000 when turned in to the agency. Non-winners will be entered into monthly drawings for 10 cash prizes of $100 each. While the reward program isn't likely to get rid of the lake's population, the agency hopes it will keep the new walleye population in check and prevent a collapse of its native kokanee fishery.

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Walleye are not native to the Pacific Northwest and prey on young salmon in many parts of the Columbia Basin. Photo: Matt Corsi IDFG.

Walleye are a relatively recent discovery in the lake, said IDFG communications manager Kiira Siitari. The population likely moved into the lake from Noxon Reservoir, by way of the Clark Fork River. She said biologists don't know whether the kokanee population is being significantly impacted yet, but will use information from the reward program to determine whether that will be an effective way to keep the population in check.

In Idaho, walleye are stocked in some lakes, with strict fishing limits. In others, the agency is working to suppress them, Siitari said. When walleye are illegally introduced, including those that made their way to Lake Pend Oreille, managers try to reduce the population, and offer fishing with no bag limits and sometimes a reward program. "They're a controversial species because, even though they're not native, a lot of people like catching them. They're a very popular sport fish," she said.

They're so popular in Montana that fishermen recently asked the Montana Fish, Wildlife and Parks Commission to reclassify walleye as native, providing peer-reviewed literature with maps showing that their native range included all of Montana east of the Continental Divide. The agency did its own research, consulted with experts from across the country and used the best available information to determine they are not, Eric Roberts, the agency's fish management bureau chief, told Clearing Up.

Montana FWP held a meeting on Feb. 28 to explain its decision to the public. "Our plan is to keep walleye as a non-native fish. Even with that, walleye are still a very important sport fish, especially in eastern and even central Montana. There's a lot of quality walleye fisheries here, and we intend to manage to keep those," he said.

However, the agency's continuing policy in much of western Montana--including tributaries to the Columbia and Snake rivers--is to keep walleye from expanding by having liberal or no bag limits. Roberts said Noxon Reservoir is a primary concern, as are any rivers or lakes where new populations arise.

After a recent discovery of walleye in Swan Lake, biologists determined they had been illegally transported and planted there from Lake Helena. "We have a mandatory catch-and-kill, and a requirement to report it and bring the fish to FWP within 48 hours so we can do biological sampling," he said.

In Washington state, two bills--House Bill 1579 and Senate Bill 5580--have made their way through legislative committees addressing the non-native status of walleye, along with bass and channel catfish. Looking to adopt some of the recommendations by the state's Southern Resident Orca Task Force, the bills include measures to better protect salmon habitat through enforcement of hydraulic codes, and attempt to increase prey for orcas by reducing salmon predation.

The House version directs the Washington Fish and Wildlife Commission to adopt rules liberalizing bag limits for bass, walleye and channel catfish in all anadromous waters to reduce predation risks to salmon smolts. The Senate bill removes the three non-native species from the state's list of game fish, which would eliminate the need for a fishing license and take away the agency's management abilities.

Chris Donley, WDFW regional fisheries manager in Spokane, said Washington, too, has many places where the state preferentially manages for walleye, and the agency sees it as an important fishery in areas like the Potholes Reservoir. "It's a highly sought-after game fish, and they're worth a lot to us economically. And they're not having an ecologic impact," he told Clearing Up.

It's a different story in the Columbia and Snake rivers, he said. "In the anadromous zone, where we're spending billions of dollars to recover salmon and steelhead, we do not view it as the same thing. The entire Columbia Basin and all the tributaries to the Snake and Columbia currently have no limit on those species," he said.

Even without a bag limit, Donley said there generally aren't enough fishermen to keep walleye from posing a serious threat to salmon--even though the Columbia has a reputation for trophy walleye fishing. In 2014, a fisherman landed a 20-pound 5-ounce walleye in Lake Wallula, formed by McNary Dam. The catch not only broke Washington's previous all-time record for walleye, but was also the first time since 1988 that a walleye larger than 20 pounds had been caught anywhere in the United States.

Donley said without scientific studies, it's hard to know how much of an impact walleye, bass or catfish are having on salmon and steelhead smolts. For years, scientists pointed to Northern pikeminnow--a native to the Columbia Basin--as the major fish predator. "What we know about walleye and bass, and to a lesser degree, catfish, is that they participate in acute predation events. It may be only a week or two days--but they hang at the mouths of tributaries or in pools below dams and they eat [juvenile salmon] at alarming rates. We have a study on the Yakima River confirming the amount of Chinook they take is mind-blowing," he said.

Donley said at other times or in other parts of the river, they may eat only a few young salmon in their varied diet, but that can add up to a lot of smolts if walleye and bass populations are high.

To begin a reward program--like one that the Bonneville Power Administration funds to control Northern pikeminnows--would first require studies to determine the numbers and sizes of walleye or bass that need to be caught to make a difference. "We do not currently have the funding to do that. When you're talking about populations of fish that are on the order of millions, to fund some sort of program like that is expensive," Donley said. "We haven't waded into that world." -K.C. Mehaffey

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NW Fishletter is produced by NewsData LLC.
Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
Phone: (206) 285-4848 Fax: (206) 281-8035

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