A relative 'Newcomer' inhabits one of Northern Idaho's river/lake systems

December 11, 2014

A newcomer is establishing itself in northern Idaho. Walleye, a staple of the Midwestern United States, have not historically been a part of the northern Idaho landscape. They have found their way into area waters fairly recently. Lake Pend Oreille, well known for its kokanee, Kamloops rainbow trout, bull trout and cutthroat is now also home to a growing walleye population. Walleye were illegally introduced into the Clark Fork River, upstream in Montana. They gradually worked their way downstream into Idaho and were detected in Lake Pend Oreille and the Pend Oreille River around 2004-2006. Although occasionally caught by anglers, substantive catches of walleye weren't really evident until 2010. The Idaho Department of Fish and Game (IDFG) completed walleye surveys in 2011 and 2014 that showed walleye are expanding. Using gill nets, IDFG biologists sampled waters from the Clark Fork delta, across Lake Pend Oreille, and down the Pend Oreille River. Catches show walleye abundance has nearly doubled in the three years between surveys. Walleye in the Pend Oreille system are growing fast. Five and six pound fish are relatively common. Although walleye are increasing, they are still relatively low in abundance compared to well- established populations in the northwest such as Washington's Lake Roosevelt, with over twice as many walleye per acre. Walleye present a unique challenge for fishery managers. They are often revered by anglers for the quality of their meat and the challenging angling experience they provide. A walleye fishery has not been available in northern Idaho, and biologists recognize it is something a number of anglers desire. Biologists recognize that new fisheries come with risks. Walleye are predators that live almost entirely on a diet of other fish. In Lake Pend Oreille and the Pend Oreille River, that means walleye may reduce the number of other species that anglers like to catch. They may also pose problems for some of the native fish in the system, such as cutthroat and bull trout. Like them or not, walleye are now a permanent part of the northern Idaho waterscape. Eliminating the population would not be possible. However, because walleye were illegally introduced and may have detrimental impacts on some of the lake's existing fisheries, IDFG will not encourage walleye population growth. IDFG has an official policy that states the Department will not promote or enhance fisheries for illegally introduced species. Rob Ryan, Regional Fisheries biologist for IDFG says the policy is intended to discourage anglers from establishing new fisheries through illegal introductions. "Although illegal introductions may provide a new fishing opportunity for some anglers, it always comes at the expense of someone else," said Ryan. Ryan acknowledges that many of Idaho's most popular fisheries are based largely on non-native fish, but notes not all introductions were well thought out. "Over the past 100 years, there have been hundreds of introductions by government agencies, sportsmen's groups, and private individuals. Many of them provided benefits, but others have caused irreparable damage." Taking into account the lessons learned, IDFG is now very cautious about stocking non-native fish into new waters, and fishery managers now implement a rigorous process to evaluate the potential impacts and benefits of new species introductions.