Wednesday was the 111th consecutive, and final, day of ice fishing this season for Gregg Hennum, co-owner of Sportsman’s Lodge on Lake of the Woods.

This weekend’s predicted warmup will congeal the deep snow piled atop the northern border lake into a slushy mess, Hennum said, making travel all but impossible and perhaps dangerous.

“Too much snow, too much slush and the snowbanks are too high,’’ he said. “We’re done for the year.’’

Farther south, hard by the shores of Mille Lacs, Terry Thurmer has similarly parked for the season the weary Ford and Chevy trucks whose transmissions have been fried and whose plows have been bent and busted this winter clearing roads for anglers wanting to fish Curley’s, Sherman’s, Banana and Rock Pile flats.

“Deep snow was the big problem,’’ said Terry’s wife, Vicky. “We probably broke our plows 20 times. Motors went out. Fuel pumps went out. It was tough.’’

Across Minnesota, largely out of the public eye, the winter angling industry — an integral and growing segment of the state’s overall $4.5 billion fishing economy — is quietly going out of business for another year.

Bait dealers. Ice-fishing contest organizers. Wheelhouse retailers. Fishshanty-rental outfits. Each is closing the books on a seasonal sport whose grip on a seemingly ever-increasing number of Minnesotans — and their pocketbooks — appears lock-tight.

Mille Lacs is an example.

Anglers there, some outfitted with high-tech electric augers and underwater cameras, among many other modern ice-fishing gizmos, could keep only a single walleye this winter between 21 and 23 inches.

Yet because that dimension is relatively rare among walleyes in the lake, Mille Lacs anglers’ chances of leaving the lake with even a single fillet to fry were minimal.

So why were some 3,500 fish houses on the lake at one time this winter? So many houses that on some mornings veritable fleets of angler-driven pickups streamed by the Department of Natural Resources’ shore-stationed creel clerks rather than wait in long lines to be asked how many fish they did or didn’t hook.

“One Sunday, one of our clerks counted 115 vehicles that passed by her in 50 minutes,’’ said Eric Jensen, the DNR’s Mille Lacs large lake specialist, noting anglers are not legally obligated to report to the clerks.

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Why people fish in the cold months — especially on a lake unlikely to yield them even a single legal walleye — is a head-scratcher, Jensen conceded.

“But it’s not a question we ask on our surveys,’’ he said.

Karen Theismann of Wabasha, Minn., thinks she knows the answer.

“What else are you going to do in winter?’’ she asked.

The office manager of the Wabasha-Kellogg Chamber of Commerce, Theismann, like many other residents of those Mississippi River towns, is both an organizer and participant in Wabasha’s annual Grumpy Old Men Festival.

Named for the movie starring Jack Lemmon and Walter Matthau, whose hangout in the 1993 film was the late Slippery Bach’s namesake burger joint in Wabasha, the annual February celebration features storytelling, a costume contest, bingo, a poker tournament and a Grumpy Plunge, during which otherwise sane people leap into the Mississippi to raise money for local charities.

But like the other 100 or so DNR-permitted hard-water competitions held in Minnesota since Jan. 1 alone — among them the Perch Jerk on Pokegama Lake and the Fishing for Ducks tournament on Mille Lacs, the centerpiece of the Wabasha festival is a fishing contest.

“I’m surprised how many fish are caught,’’ Theismann said, “from itty-bitty perch to big northerns.’’

Catching fish is nice, James Ly agreed. But it’s not necessary to have a good time while winter fishing.

Ly, of Lakeville, is among a group of Twin Cities residents who regularly drive north to Leech Lake in winter, where they fish in portable shelters hoping for a walleye or northern pike to bite, but oftentimes settling for tullibees and whitefish.

“We deep fry them and they’re good to eat,’’ Ly said. “But I don’t have to catch any fish to have a good time on Leech Lake in winter. We fish there because it’s peaceful, it’s quiet and we’re out in the open, with fresh air. It feels good.’’

Ly and transient anglers like him have been critical this winter to the retail bait business, said Ben Kellin of Ben’s Bait and Tackle in Grand Rapids.

“When there’s a lot of snow, like there has been this winter, local anglers tend to fish less,’’ Kellin said. “In that respect, anglers passing through to Upper Red Lake and Lake of the Woods, especially those who own wheelhouses, have really helped us. They’ll stop to buy bait on their way to those lakes.’’

Yet winter fishing’s upward popularity trajectory is not without its costs, Kellin said, noting that many Minnesota bait ponds have been overharvested to supply anglers’ needs.

DNR fisheries managers also worry that excessive numbers of bluegills and crappies are being caught and kept in winter, and that on Lake of the Woods, where winter fishing pressure has jumped by more than 1 million angler hours in the past two decades, the sauger catch in recent years is unsustainable.

Hennum, the resort owner Up North, shared these concerns. But on Wednesday, his 111th and final day this winter in the ice fishing business as co-owner of Sportsman’s Lodge on Lake of the Woods, he was ready for a vacation.

“But I can’t take one yet,’’ he said. “My son is in bantam hockey, and he still has more games to play.’’