(Idaho Fish and Game Press Release, October 25, 2023)
Like a romcom movie, the relationship between walleye and Idaho is complicated. Some anglers enjoy them as a tasty fish, but walleye tend to upset the balance of existing fish populations, so it won’t be an entertaining story if walleye populations expand across the state.
Idaho and walleye just aren’t a good match in most places, and here’s why. Walleye are native to large Midwestern lakes that tend to have large and prolific forage bases of minnows, shiners, chubs and other small baitfish. Those baitfish are not available in most Idaho waters, so walleye are likely to eat other game fish that are highly valued by Idaho anglers. Eventually, those other fish species could be gone, or greatly diminished, and the end result could be a bunch of unhealthy, unsustainable walleye populations.
Not exactly a happy movie ending, and unfortunately, the prequels have already played out in far too many waters in surrounding states.
That’s why Idaho Fish and Game is extremely selective where it provides walleye fishing, which is currently limited to three locations: Salmon Falls Creek Reservoir, Oneida Reservoir, and Oakley Reservoir.
Fish and Game asks anglers to kill all walleye they catch outside of those waters, and to report any of those fish to a regional Fish and Game office.
Walleye are being discovered by Fish and Game biologists in waters where they aren’t wanted and were likely illegally released. Most recently in Lake Lowell near Caldwell, but sporadically in other Idaho waters as well. Some are also naturally migrating into places where they could harm resident and ocean-going fish populations, such as in lower Snake River near Lewiston.
Fish and Game has an ongoing project in Lake Pend Oreille in North Idaho to keep established walleye populations from growing and consuming kokanee that provide a popular fishing opportunity, as well as feeding trophy trout populations in Idaho’s largest lake.
Not a bad fish, just the wrong fish for Idaho
Some anglers have accused Fish and Game biologists of being biased against walleye, which isn’t true. Biologists have spent decades surveying anglers for their preferences, and biologists have done their best to provide diverse fishing opportunities that are geared toward angler preferences, which includes walleye fishing.
However, in most Idaho waters, biologists aren’t managing a single species, they’re managing multiple species that must be somewhat compatible with each other. Any given water can only support so many fish, and while it’s common for game fish to feed on each other, there’s an opportunity to maintain a reasonable balance between species.
Biologists take all those factors into consideration before introducing a fish species into any water. Unfortunately, in the case of Lake Lowell, someone decided to illegally release walleye that are showing signs of successfully reproducing.
“When a highly predatory species is introduced to a water outside that established process, as walleye were in Lake Lowell, we are forced to dedicate a lot of resources towards assessing the impact on the existing fishery, and unfortunately, most of our anglers are robbed of the opportunity to weigh in on the matter,” Fish and Game’s Southwest Region Fisheries Manager Art Butts said.
Walleye are a valued fish with a checkered history
Walleye are among the favorite fish species in the some parts of the country, particularly the upper Midwest and Great Lakes area where the fish flourish and anglers love to catch and eat them.
But numerous cases in the Northwest and Rocky Mountain states have shown a fairly predictable trend after walleye populations are established in waters that didn’t previously have them. At best, the available fish species shift and another fishing opportunity is added. But more often, a limited walleye fishing opportunity displaces established and valued fish populations of other species.
Case in point is Canyon Ferry Reservoir in west-central Montana. The reservoir had a thriving perch population, as well as a healthy trout population. In the 1990s, anglers started catching walleye, which were previously unknown in the reservoir.
Walleye populations quickly grew and by 2000, their average size had grown to the point they were effective predators of perch and trout. By 2004, nearly all the perch were gone, and trout populations had also plummeted. Montana shored up the trout population by planting catchable fish rather than fingerlings, but overall, trout angling efforts were roughly halved.
Anglers turned to walleye, which offset some of the loss of angling effort, but perch populations never recovered, and interest in trout fishing declined. Walleye fishing continues at Canyon Ferry Reservoir, but largely for small to medium-sized fish because they’ve consumed most of the available forage.
Moses Lake in Washington is another case where walleye have dramatically changed a fishery. In the early 1980s, the lake’s crappie population crashed, and when Washington Department of Fish and Wildlife biologists surveyed the lake, they discovered a walleye population.
According to WDFW fisheries biologists Marc Peterson, the walleye population there “expanded before we knew what was going on.”
In the decades since, he’s seen walleye shift the lake’s entire fish population from crappie, bluegill and largemouth bass to mostly walleye and smallmouth bass as the predominate species. He added that other fish species still exist, and their populations can fluctuate from year to year, but “you can change the complexion of a lake’s entire fish composition with walleye.”
Idaho’s salmon and steelhead runs could take a hit
Walleye have long existed in the Columbia River, and now they are migrating upstream into the Snake River, and monitoring at Lower Granite Dam downstream from Lewiston is showing more walleye moving upstream.
“Salmon and steelhead did not evolve with these nonnative predators and can be especially vulnerable to predation,” Fish and Game anadromous fish biologist Marika Dobos said. “Walleye only add to the many difficulties that salmon and steelhead face, and as walleye expand their range and abundance in large rivers, more hungry mouths will be eating salmon, steelhead and other native species. This is especially important for wild juvenile salmon and steelhead that often overwinter and rear in large rivers in Idaho before making their journey to the ocean.”
Protecting Lake Pend Oreille
Fish and Game biologists are working to keep walleye at low density in Lake Pend Oreille by using commercial netting and angling. A commercial fishing company nets walleye for several weeks each spring, and biologists implant transmitters in walleye to track their location and share that information with anglers to improve their catch rates. Anglers can get money by turning in walleye heads they harvest, and this helps increase fishing effort for walleye. This program has been largely successful so far, but will likely need to continue indefinitely to balance the lake’s predator and prey populations and sustain one of the most popular recreational fisheries in Idaho.
Too risky to take a chance
Biologists understand that each body of water reacts a little differently to a new species. Many of Idaho’s large lakes and reservoirs see one species thrive, then decline, then come back on a cyclical basis because shifting environmental conditions often favor one species over another.
But considering the basic needs of walleye, which is a large, prolific forage base, the odds are in their favor when competing with other game fish.
Idahoans have repeatedly told Fish and Game biologists their preference, which is overwhelmingly healthy trout populations, followed by bass, panfish, salmon and steelhead, catfish, etc. Other anglers are simply interested in any fish they can catch, and a minority of anglers have asked for more walleye opportunities.
Biologists know choices have to be made because while many waters can support a variety of fish, including species that compete with each other, but adding a predatory fish like walleye typically means they will come at the expense of, and possibly the eradication, of other fish that Idaho anglers prefer.
Walleye and illegal transplants will cost all anglers
Regardless of how walleye get into Idaho, biologists have to deal with them, which will take them away from other projects. Because walleye could potentially (and likely) negatively effect on other fish populations, biologists will have to spend more time and effort surveying those waters and using different management strategies to minimize their impact.
For example, biologists may have to shift from stocking inexpensive fingerlings to more expensive catchables so the small trout don’t get consumed by walleye. That could easily cost tens of thousands of angler dollars annually.
One simple solution
People simply should never move live fish from one body of water to another, and they should report anyone who does. It’s not only illegal, it can be very harmful and risky to other wildlife and habitat.
Currently, Fish and Game has been able to manage walleye where they occur, but they can only do so much, so keeping walleye out of other waters will benefit Idaho’s valued fisheries.