Managing Sport Fisheries
Walleye have dramatically changed fish communities in the western United States. Idaho Fish and Game’s, Roger Phillips. "They are a very predatory fish.” Canyon Ferry Reservoir in Montana provides a cautionary look at how walleye can eat themselves out of house and home. Illegally introduced in the 1980’s, walleye depleted the prey base in the reservoir, collapsing perch, rainbow trout, and white sucker populations over the next decade. Following the loss of prey, walleye condition and size dropped. Ultimately, angler satisfaction in the entire fishery declined due to walleye.
Lake Pend Oreille has long been known for its trophy rainbow trout and bull trout, having produced world records for both species. Along with being a popular sportfish, kokanee are the primary prey base for these trophy fisheries and therefore considered the backbone of the fishery. As history shows, a downturn in the kokanee population can have reverberating effects across a lake’s food web.
For example, borrowing a page from lake trout management,
just over a decade ago, lake trout threatened to collapse the kokanee fishery in Lake Pend Oreille. Similar to walleye, lake trout are an introduced, top-level predator in the lake ecosystem. Since 2006, Fish and Game staff and the angling community have worked to manage and suppress lake trout. Angler rewards and commercial netting were the tools used to reduce lake trout abundance.
The program is a success, as kokanee are now highly abundant and the trophy rainbow trout fishery is outstanding. A similar management approach may work to limit walleye population growth but biologists want to test this strategy before committing long-term.