MINNEAPOLIS — Fisheries officials extended the walleye angling closure on Mille Lacs Lake for an extra two weeks on Friday, acknowledging the pain it will cause to businesses on the popular lake but saying it’s necessary to ensure the long-term sustainability of its struggling walleye population.

The decision means walleye fishing on Mille Lacs will remain closed until Friday, Aug 11, instead of reopening July 28 as previously planned. The lake will then reopen for catch-and-release-only fishing for walleyes through the Labor Day weekend, when the season will close again as planned through Nov. 30, the Department of Natural Resources said.

DNR Commissioner Tom Landwehr said he recognizes the extended closure is “profoundly difficult” for Mille Lacs anglers and the area’s business community, but it’s what the agency needs to do to try to restore the fishery and comply with its agreements with Ojibwe bands that have treaty rights to a share of the lake’s fish.

The decision was prompted by new data that show how anglers already have exceeded the negotiated kill quota of 44,800 pounds of walleyes this season. The DNR will dip into a reserve of 11,000 pounds that it will have to pay back over the next three years, along with a 6,800 overage from last year, Fisheries Chief Don Pereira said in a conference call with reporters

In previous seasons the cap included walleyes kept by anglers plus those that die after being caught and released, a problem known as hooking mortality. Since anglers haven’t been allowed to keep any walleyes this season, the totals represent estimated hooking mortality only, without any harvest.

Landwehr said it’s too early to know what exceeding the limit this year will mean for next season. He said the DNR will first need to conduct its annual fall population assessment to get a better idea of how much walleye fishing Mille Lacs can sustain in 2018.

The DNR and Gov. Mark Dayton have been urging anglers to pursue the lake’s smallmouth bass, northern pike and muskellunge instead. Those seasons remain open, with some restrictions. The governor tried to go bass fishing there two weeks ago but was interrupted by a flotilla of protesters opposed to the temporary walleye ban.