Ice fishing can have varied impacts

Can you catch more and bigger fish in Sunset Country through a hole in the ice in the winter than from a boat in the open-water season? What about specific species?
Are Rainy Lake walleye more prone to bite under a blanket of ice and snow? Do creel surveys suggest hard-water anglers have an upper hand? Or one hand tied behind their backs?
And what about icy impacts? Can ice fishing affect your favourite fishery?
Those were just a few of the questions I wondered about recently when I spoke with several biologists across the heart of ice-fishing country. As usual, when you’re dealing with complex fisheries’ questions, the answers ranged from yes to no, with several definite “maybes.”
According to Wisconsin biologist Steve Hogler, winter anglers have returned nearly every northern pike tag he has ever received. Open-water anglers, on the other hand, have returned nearly every bass tag.
It is not surprising given the reluctance of warm-water fish to eat more than a marginal meal in winter. But cold water-loving lake trout, speckled trout, splake, whitefish, herring (tulibee), and burbot feed heartily under the ice.
So do many cool-water favourites like northern pike, walleye, and perch.
Lake trout, though, are the embodiment of a winter angler’s dream fish. Lakers love cold water. The summer, with its soupy conditions and reduced oxygen levels in the deeper parts of a lake, actually can be a stressful time for the trout.
Indeed, lake trout bite so well in the winter when they’re confined to small, reasonably accessible lakes, over-harvest issues worry managers. A fact that is apparent to ministry researchers studying the effects of ice fishing on Squeers Lake near Thunder Bay.
Carl Wall, angling program manager with the Manitoba Department of Conservation, says the same thing is problematic in brook trout lakes. He notes stock depletion is not a concern in southern Manitoba, where brook trout are planted in lakes on a put-and-delayed-take basis with the specific intention of being caught.
But in remote speckled trout waters that rely on natural reproduction, over-fishing in winter can be cause for concern.
For this reason, Wall says Manitoba prohibits ice fishing for trout in creeks, streams, and rivers. Most of the Prairie province’s trout streams are small and the fish cram into relatively few isolated deep pools, where they are extremely vulnerable to ice fishing.
Still, when over-harvest is not an issue, winter is typically the best time to target cold-water species like trout, splake, and whitefish.
As if to underscore the point, biologist Stephen Schram points out that in Lake Superior, where ice fishing generally has no adverse affect on the trout population, winter anglers catch up to a quarter of Wisconsin’s fish.
It is especially true when ice conditions are good and anglers can gain easy access.
Perhaps nowhere is the affect of ice conditions and winter accessibility more evident, though, than on the big ice of Lake Michigan’s Green Bay, where fishing for yellow perch attracts legions of anglers.
During the 1990 and 1991 ice-fishing seasons, biologist Terry Lychwick says two million perch were hauled up through holes in the ice each winter. That was compared to 1.5 million perch caught by anglers fishing during the much longer open-water season.
According to Lychwick, thousands of anglers descended on Green Bay during those two winters when weather, ice, and travel conditions were ideal. That is in contrast to the open-water months when wind and waves can keep you shore-bound for days.
On more moderately-sized lakes, like the 7,000-ha Lake Scugog, north and east of Toronto, summer and winter accessibility is about the same. MNR creel data show neither open-water anglers nor their ice fishing counterparts enjoy an advantage and walleye harvest rates are almost identical.
One of the things that can drastically influence ice fishing success is the quality of the forage base. Kendall Kamke is responsible for managing the Lake Winnebago system and for the last several years, he says the open-water harvest of walleye and northern pike has far outnumbered the ice harvest.
On the Winnebago system, as elsewhere, sport fish populations largely are dependent on summer forage levels. When forage is abundant during the summer and fall, sport fish go into the ice-covered period healthy and well-fed.
As a result, ice anglers typically experience mediocre fishing for walleye and pike.
When forage fish are scarce, however, Kamke says predators likely are to feed more actively under the ice. Indeed, during winters of abnormally low forage crops, he says ice fishing can have a dramatic impact on the number of sport fish and the structure of the population.
It is precisely what occurred during the late 1980s and early 1990s when Winnebago experienced a huge increase in shad as a result of warm weather conditions.
With a plentiful food supply, walleye and northern pike flourished. Test nets revealed above average numbers of 40-inch plus pike.
Then the shad base collapsed during the unusually cool summer of 1992. Pike went into the winter hungry and ice fishermen enjoyed incredible action.
Too much of a good thing some might suggest. So many large pike—typically egg-laden females—were harvested that trap nets set the following spring revealed pike numbers were down between 64 and 81 percent from previous surveys.
Kamke says that from a northern pike size structure point of view, the Winnebago system still is recovering a decade later from that one winter harvest.