A strong north wind whips across the large lake, sending white-capped waves crashing upon the shore. It's been only days since the ice melted. The water temperature rises grudgingly into the 40s. Beneath the waves, atop shallow, rocky shoals, walleyes are in the midst of their annual spawning cycle. Male walleyes fertilize the hundreds of thousands of yellow eggs that females produce, and if everything goes right, the newly fertilized eggs will fall into the nooks and crannies of the shoal below, where the wind-driven current oxygenates the eggs and keeps them free of algae and other substances that could suffocate them. Soon, swarms of mosquito-sized walleyes will hatch.
Places like this are where most Minnesota walleyes begin their lives. But these conditions are relatively uncommon, occurring on only about 260 of the 1,600 state lakes where walleyes are present. Lakes with big, windswept shoals include some of the state's most well-known—Cass, Leech, Vermilion, Winnibigoshish, Upper Red, Mille Lacs, and Lake of the Woods among them—and account for about 85 percent of the walleyes anglers harvest each year. However, in the majority of lakes where walleyes exist, it's because of a $3 million annual stocking program that provides anglers with opportunities they wouldn't otherwise have to catch Sander vitreus, Minnesota's state fish.
While stocking can't create fisheries that are on par with the state's best walleye waters, it "can create modest walleye fisheries where they otherwise wouldn't exist," says Department of Natural Resources Fisheries chief Don Pereira, who notes the state has a long history of fish stocking. "Fish management here started as fish culture way back in the 1800s. Back then, fish management was simply stocking fish and putting them everywhere we could so people would have more fish to catch and consume. We knew nothing about ecology, we didn't know that native fish [could provide strong fisheries on their own], and we did some incredibly naïve things."
The agency's biologists and scientists know a lot more today, having honed the state's stocking programs in recent decades and studied the outcomes. Most recently, they've discovered ways to make walleye stocking more efficient. In 1999 a project dubbed the Accelerated Walleye Program began doubling the number of cigar-sized fingerling walleyes stocked in 254 lakes around the state. The results of those massive stocking increases were generally poor, according to a review that compared pre- and post-stocking gillnet catches: 70 percent of the lakes did not see increases in walleye populations.
"We doubled the base rate for fingerling stocking, and the broad view is it didn't move the needle," says Doug Schultz, DNR area fisheries supervisor in Walker. "In many cases, fingerling stocking was already working, but stocking twice as many fingerlings didn't work better. Walleye populations increased in only about one-quarter of the lakes. They decreased in about one-quarter of the lakes, and the rest of the lakes had increases or decreases of about three fish per net. That really isn't a meaningful change for most lakes.
"The big message from all of this is it's always trial and error when it comes to stocking fish. Our systems are always changing, and what worked today maybe didn't work 20 years ago, and vice versa."
The road here
The earliest records of walleye stocking in Minnesota date back more than 100 years. Those stockings consisted of fry—mosquito-size walleyes—stocked in lakes shortly after they've hatched. By the 1940s refinements led to the stocking of more fingerling walleyes, which are 4 to 6 inches in length. (Walleyes are not stocked in Minnesota rivers, which often hold self-sustaining populations.)
Fisheries managers of the time gave little thought to where stocking should occur or its effect on existing fish communities.
The 1970s and 1980s saw a more systematic walleye-stocking approach based on individual lake plans and stocking guidelines for various types of lakes. In the late 1980s, the DNR reduced the number of walleye fingerlings and the overall number of lakes that it stocked on the recommendation of a 1986 report from the state auditor on the state's fisheries management. Then, a University of Minnesota review in the mid-1990s found stocking walleye fingerlings in lakes with natural reproduction was not likely to increase fish abundance and could impede the growth of individual fish. This, coupled with budget cuts, caused the DNR to stock even fewer fingerlings.
DNR data at the time indicated that walleye populations in fingerling-stocked lakes were generally increasing or stable, but many anglers perceived that walleye fishing had declined on many of the lakes where stocking was reduced. Public discontent resulted in a series of meetings on walleye stocking in the Minnesota Senate. Those meetings paved the way for the Accelerated Walleye Program in 1999, which aimed to reverse course and again increase walleye fingerling production. The DNR hired an independent consultant to review the program's implementation, and the consultant recommended doubling the rate of stocking to 1 pound per littoral acre (the area of a lake less than 15 feet in depth) per year.
In the early 2000s, the agency adopted that fingerling-stocking rate as the statewide standard, with a preference for every-other-year stocking. Both anglers and advocates for increased stocking had high hopes for the program and expected it to boost walleye catches.
Evaluating the program
In 2015, DNR Fisheries set out to evaluate how the increased rate of fingerling stocking had worked out on the 254 lakes where fingerling stocking was doubled. They compared gillnet catches before and after the increase. Some lakes showed increases, while others showed decreases. In most lakes, there wasn't a meaningful change in gillnet catches.
When walleyes reach 3 years of age, they become less vulnerable to predation and are considered recruited into the population. These fish, which are 13 to 15 inches long, are also at the size where many Minnesota anglers consider keeping them. In 52 percent of the Accelerated Walleye Program lakes, walleye recruitment hadn't changed. It declined in 20 percent of the lakes and increased in 17 percent of them.
Additionally, the mean gillnet catch in lakes that were part of the Accelerated Walleye Program wasn't higher than in other walleye lakes across the state. As part of the program's analysis, researchers examined other factors including the abundance of walleye prey, such as perch, and predators, such as northern pike. They found that walleye catches were higher where yellow perch catches were higher. In lakes where northern pike catch rates were higher, walleye catches were lower.
As a result of the review, 70 of the lakes will continue to be stocked at the increased fingerling level. Stocking density will be reduced on 85 of the lakes. On 10 lakes, stocking density or stocking frequency will be increased. On 36 lakes, managers will stock walleye fry instead of fingerlings. Stocking will be discontinued on 8 lakes, and evaluation of increased fingerling stocking will continue on 45 lakes. Across all 254 lakes, that means 55,626 pounds per year of fingerlings will be stocked, which is a reduction of 24,852 from the previous annual average.
While this may appear to be a major change to fish management in Minnesota, it's not much different from the process the DNR undertakes on all the lakes it manages, according to Schultz. "We implement a management action on a lake, give it 10 or 12 years to have an effect, and then evaluate it to see if we are meeting our management objectives," he says. "If not, then we make a change. In reality, it's what we've always been doing."
Neil Vanderbosch, the DNR Fisheries consultant who oversees the state's walleye-stocking program, says area fisheries managers will continue to work with lake associations and will tie stocking levels to individual lake management plans. Those plans take into account such factors as available habitat, results of past stocking efforts, and the presence of prey.
Pereira says that in an era of limited budgets, the DNR is trying to be a good steward of anglers' dollars. That, in part, means taking a close look at what's being put into lakes and comparing it with what's coming out, while keeping in mind the extent to which Minnesotans and tourists treasure walleyes.