Winnebago's Walleye Fishery: Can It Last?

Lake Winnebago's walleye fishery is robust today, having rebounded from a serious decline in the 1970s and '80s. Photo by Ron Sinfelt.

For as long as anyone can remember, there have been walleyes in Lake Winnebago, and for most of that time walleyes have provided good fishing on Wisconsin's largest inland lake. In fact, Winnebago's walleyes are the stuff of legend.

"Walleyes and Winnebago are almost the equivalent of Paul Bunyan and the blue ox lore," said Kendall Kamke, the Wisconsin Department of Natural Resources fisheries biologist in charge of managing Winnebago's walleyes. In his tenure, Kamke has seen a boom, bust and rebuilding of the lake's walleye population. He has watched over their spawning marshes in spring like a mother hen, monitored their growth rates, checked on the availability of their food supply, and in the course of his work has handled literally tons of the golden-flanked fish from fry to older adults.

In 2008, Kamke reached a milestone when he put tag No. 100,000 on a Winnebago walleye.

"That big female was kind of special to me," Kamke recalled. "Tagging began in 1989 and continues today to allow us to conduct index population estimates and minimum angler exploitation rates."

Today, Winnebago's walleye population is robust, with a good representation of year-classes. Saugers, too, have made a comeback and are doing well. (Editor's Note: We reported on the sauger comeback in the March 2006 issue of Wisconsin Sportsman magazine.) There was excellent fishing a generation ago, too, but that has not always been the case. Between then and now, Winnebago's walleyes took a hit and recovered, causing some people to think the lake's walleye population might be cyclical, rising and falling in response to some forces external to the walleyes themselves.

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Kamke is skeptical of the cyclical theory: "Does one boom and bust make a cycle?" he asked. "Until we have another crash, we wouldn't really know."

And of course, Kamke hopes to avoid another crash.

RECENT HISTORY
Over the past 40 years, Lake Winnebago's walleye population has gone full circle. In the early 1970s, walleye fishing was phenomenal. Thanks to excellent reproduction, walleye numbers in the lake were high. So high, in fact, that the walleyes apparently ate up most of the available forage.

"We had what was perhaps a 'perfect storm,' " says Kamke. "We had a high population of adults that ate the cupboard bare. Then we had high adult mortality, lots of older fish dying of old age, and they were in poor condition. During the late 1970s and early 1980s, walleyes were small and skinny. A 5-pounder was a real bragger."

Some anglers and biologists thought these sickly walleyes might have some kind of disease, so samples were sent to fish health specialists in Madison for evaluation. It turned out that the walleyes were just starving. The adult population had reached a point where the forage base could not supply enough food to keep the walleyes healthy and growing.

That situation set the stage for a population crash, and subsequent environmental conditions sealed the deal.

"We had a large population of older fish that were dying of old age and a low forage base," Kamke says. "Then in the late 1980s, there were four years of almost no reproduction because of low water levels in the spawning marshes in spring. That created a gap in the population."

Then in 1990, adequate spring water levels helped the remaining walleyes pull off a successful spawn and produce the first decent year-class in nearly a decade.

"It was almost like starting fresh," says Kamke. "Luckily, the forage base had rebounded and could support the influx of walleyes. That forage base has kept up with the walleye population since then. Anyone who has caught walleyes here in the last decade will tell you they are stuffed with fat."

On top of that success, the state and local sportsmen's clubs have conducted a lot of habitat work in recent years that is paying off. Most of Winnebago's walleyes spawn in marshes on the Fox and Wolf rivers. These are shallow wetlands connected to river backwaters that fill with water in early spring, allowing walleyes to gain access to them. When conditions are right, walleyes spawn in these marshes, their eggs hatch in the warm, shallow water, and then spring rains flush the just-hatched walleyes out into the rivers and down to lakes Poygan, Butte des Morts, Winneconne and Winnebago.

From the 1960s to the 1990s, road and residential construction had blocked the flow to some of these waterways and contributed to a decline in the quality of vegetation in spawning marshes, resulting in poor spawning success even during the years when walleyes could get into the marshes. Sportsmen's clubs, municipalities and state agencies such as the WDNR and Department of Transportation, recognized the importance of spawning habitat and gradually made improvements that revived the spawning marshes. The walleyes responded, and today Lake Winnebago and the upstream lakes boast a destination walleye fishery.

EXOTIC INVADERS
Exotic species have been in Lake Winnebago for more than a century, Kamke points out. European carp were the first invaders, and they are still present. "They have been here so long they're almost a native by now," Kamke says. "But they are still detrimental, rooting up vegetation and contributing to water turbidity."

More recently, zebra mussels have found their way into the lake, probably transported there from Lake Michigan by unsuspecting boaters. Kamke doesn't believe zebra mussels pose a significant threat, however, because there is not that much hard bottom to provide them with needed habitat.

"They are either in check or else their numbers ebb and flow," he said. "They may have reached the carrying capacity of the available substrate."

Zebra mussels have had some localized impact, but they have not caused lake-wide damage. Alive, they can clog water intakes and build up on piers and other hard structures. Their dead shells can pile up on beaches. Kamke knows of one shoreline resident whose small cove has repeatedly filled up with zebra mussel shells. He has spent thousands of dollars hauling them away.

Quagga mussels, a deep-water exotic that affects Lake Michigan, might be a different story, but they have not yet shown up in Winnebago.

Another exotic, the Chinese mystery snail has been found in the Wolf River above Shawano, so it is likely a matter of time before this invader reaches the lake. These snails are extremely prolific and capable of crowding out native species. Will they cause a problem when they get to the lake? Only time will tell.

Viral hemorrhagic septicemia, or VHS disease, has been found in the lake, but this exotic disease hasn't caused any major problems yet.

"We had one fish kill in 2007 from VHS in freshwater drum (sheeps­head)," said Kamke. "We haven't seen any outbreak since then, but we are still watching for it. We did a fairly ambitious sampling of fish last fall, but haven't seen any mortality attributable to VHS. We don't know if it's present but in low quantity, if it's in a resting state, or if we have carrier fish. We've got a lot of questions, but not many answers."

Last fall, Kamke sent 250 walleyes and 250 sheepshead to the WDNR lab in Madison for disease testing. Last spring, 50 or 60 walleyes were tested. So far, everything has come back negative. Kamke is cautiously optimistic, but he said we must remain vigilant until it becomes apparent the disease is gone or no longer a threat.

"VHS has a great potential impact," Kamke said. "In spring, you have fish already stressed by spawning, water temperatures in the range where the disease is active and lots of fish in close proximity. Should there be an outbreak, we could lose thousands of walleyes in a very short time."

Rusty crayfish are another non-native species, but they don't appear to have had a big impact on the fishery. In some inland lakes, they have practically wiped out aquatic vegetation.

"We've had rusty crayfish for awhile, but we don't seem to have the habitat they need. They probably wouldn't have much impact on walleyes, but they could hurt panfish populations," Kamke said. "If we lost our panfish, we'd lose some food for walleyes, but the crayfish probably don't have the capability of reaching sufficient numbers to decimate our vegetation."

Kamke believes Asian carp -- bigheads and silvers -- could thrive and have a huge impact in Winnebago, but so far, they have not arrived.

"We've been lucky to dodge a lot of exotics, and I hope it stays that way," Kamke said. "People need to stay vigilant, however. If anglers get complacent and don't clean out their livewells, we could be in trouble."

CLEAN WATER, MORE VEGETATION
Lake Winnebago is noticeably cleaner now than it was just a few years ago. As a result, aquatic vegetation now flourishes where it was previously nonexistent. Aquatic vegetation provides food and hiding places for young fish and a place for predators to hide. The increased vegetation has played a large role in the recent growth of the panfish population. Crappies, perch, white bass and bluegills have all increased in number in recent years. They add to a balanced fishery, and their young provide food for walleyes.

Some observers credit zebra mussels with the cleaner water, but Kamke says their impact is probably minimal because they inhabit a small ring of rocky habitat around the outside of the lake.

Instead, the same player that caused most of the water-quality problems -- man -- has worked to resolve them, Kamke said.

"The system as a whole has benefited from millions of dollars spent by communities and the state to reduce both point and non-point sources of pollution and thus reduce the inflow of nutrients," Kamke said. "Better agricultural practices, such as contour plowing, buffer strips and manure management have also helped. And there are new rules to control runoff in construction sites. None of that would show results overnight, but in the last decade we're starting to reap the benefits."

All four of the Winnebago Pool lakes have benefited, but Lake Winnebago has shown the greatest improvement because it is "at the bottom of the drain" as Kamke puts it. In the 1970s and '80s, Lake Winnebago turned green shortly after ice-out in spring and remained murky all summer. That has not occurred in 10 years, Kamke said. Much of the lake remains clear all summer, thanks to the aquatic vegetation that filters the water and reduces turbidity.

Turbidity is still a big problem in the rivers -- the Fox and Wolf -- that feed the system. Early spring rains will wash silt from farm fields before crops get going. Wakes from boats of all sizes also contribute to turbidity all summer long, Kamke said.

WHAT'S AHEAD?
For the short term at least, the walleye picture looks bright. A huge hatch in 2008 produced a year-class that will probably dominate the fishery for the next decade. Those fish will be 12 inches long or so this spring. The class of 2009 was much smaller, but those fish will still make a contribution.

"If we had a hatch like we did in 2009 every year, we'd probably have a pretty good fishery," Kamke said. "I hope we're not ramping up like we did in the 1970s where we'll see a problem with the forage base. It doesn't look like it because we had a good hatch of trout, perch and gizzard shad last spring, and there's always the venerable drum to provide forage for walleyes.

"Unless we're missing something, we can expect the walleye fishery to continue strong for the near future. About the only two things that could drive a drastic reduction of the fishery would be a disease problem, like VHS, or a forage base collapse."

CATCHING WALLEYES
Traditionally, most anglers jigged Winnebago's reefs for walleyes, and this method is still one of the best. There are good maps that show the reefs scattered along the west and east shores. Working the windward side of these reefs with a small jig tipped with a minnow in spring and a crawler, leech or plastic tail in summer will take fish. You can also catch them by casting shallow-running crankbaits over the reefs.

Anglers have recently discovered that walleyes also hang out in the shallow weeds. This should come as no surprise, as this vegetation teems with baitfish. Weedless spoons, slip-bobbered leeches and spinnerbaits all work on these weed-eyes.

The biggest development in the past 20 years or so has been the advent of deep-water trolling.

Popularized by tournament pros, this method targets the larger walleyes that suspend over the lake's mud flats in 15 to 20 feet of water. Serious trollers use planer boards to spread their lines out and drag crankbaits or crawler harnesses at different depths to pick up suspended fish.

Whatever method you use, it is hard not to catch walleyes now that the lake is full of them. From the looks of things, this bug-eyed bonanza will continue for the foreseeable future.