ST. PAUL — Minnesota’s Department of Natural Resources announced Sunday it will close Mille Lacs Lake for walleye fishing tonight, a first for the state’s marquee walleye lake.

Years of dropping walleye populations in the central Minnesota lake combined with heavy fishing in early July that surpassed the state-imposed harvest quota led to the decision. The state had to choose between closing the lake, which will likely harm area resorts and businesses that cater to anglers, or risk irreversibly harming the lake’s walleye population, Department of Natural Resources Commissioner Tom Landwehr said.

“This is a pretty dark day for anglers and businesses in the Mille Lacs area,” Landwehr said. “We’re sort of in a box here.”

The closure, which begins at 10 p.m. Monday, highlights the precipitous decline of walleye at Mille Lacs that prompted years of increasingly strict quotas. A 500,000-pound quota in 2012 fell to 40,000 pounds this year, with a one-fish harvest limit.

The department previously said a surge in walleye catching in July put them on track to close the lake by Aug. 3. Landwehr said Sunday that the latest survey at the lake revealed anglers had surpassed the quota by 2,000 pounds.

State officials tentatively plan to re-open the lake for winter fishing on Dec. 1.

Today’s closure will also further fuel calls to step in to provide financial assistance to resorts and businesses in the Mille Lacs area.

Gov. Mark Dayton wants a special session of the Legislature, and a working group of lawmakers is expected to assemble later this month to hash out a financial assistance package that could include zero interest loans and funds to promote fishing for other species, such as bass, northern and muskies — a point that Landwehr stressed after announcing the closure.

But in the long term, Sunday’s decision prompts a deeper examination of what’s behind the fish’s decline and how to reverse it. Landwehr said the department hopes to establish a research station to better monitor what’s at play and determine whether restocking it is a viable option.

“The lake could be going to a different equilibrium. We really don’t know yet,” said Don Pereira, fisheries section chief.

Landwehr called the Mille Lacs Band of Ojibwe’s recent decision to halt walleye netting on the lake a “nice gesture” that ultimately won’t have a marked effect on the population.