Lake Mille Lacs has been called the “walleye factory” for decades by Minnesota’s anglers.

The decision by the Minnesota Department of Natural Resources (DNR) to close walleye fishing on Mille Lacs, less than three months into a nine-month season, is an unprecedented blow for the sports-fishing industry that generates more than $2 billion for the state economy.

Gov. Mark Dayton has called for a special session to consider aid for businesses coping with the financial hit. If legislators meet, we hope the discussion focuses on solutions instead of assigning blame, even if there is plenty of culpability to pass around.

The walleye population on Minnesota’s most popular fishing lake is at a 40-year low, so the impact on resorts, restaurants, bars, bait shops, fishing guides and charter-boat services dependent on tourism will be huge. The businesses relying on sport fishing can operate much the same as they have, but any hooked walleyes must be released immediately.

The catch-and-release strategy won’t necessarily help the walleye population recover. A phenomenon called “hooking mortality,” where a walleye dies after being released, is at a level never seen before. The DNR estimates that during the first two weeks of July, anglers kept about 2,000 pounds of walleyes, while an additional 10,000 pounds died from hooking mortality.

DNR surveys show that the lake has plenty of spawning females and young walleyes, but for some reason they are not growing into mature adults.

There is hope in a generation of fish that hatched in 2013, when a record number of walleyes were born. These fish provided much of the action for anglers this year, but they haven’t reached reproductive age yet.

The DNR suspects that a confluence of factors — such as invasive species, warmer water temperature and other components — is altering the lake ecosystem. The northern pike, whose population is at a record high, is a predator of walleyes. Walleyes are cannibalistic, so the larger fish eat the smaller fish. Water clarity has improved — often attributed to the invasive zebra mussel — possibly making walleyes more vulnerable to predators. The smallmouth bass population has boomed in recent years, but DNR officials say walleyes are not a significant part of their diet.

The Mille Lacs Band of Ojibwe, one of eight American Indian bands that retained fishing rights to the lake through an 1837 treaty, agreed last week not to net walleye next year to help rebuild the fishery. We commend the Mille Lacs band for its leadership and hope the other seven groups will follow suit.

Many accuse the DNR of mismanaging Mille Lacs. Others accuse the tribes of overfishing, even though the DNR dismisses that as a factor for the plummeting population. Don’t point fingers at any particular group. What’s happened is a perfect storm of invasive species, climate change, and runoff from lakeside development and nearby row crops. We all share responsibility for this natural disaster.

Until the walleye population rebounds, we’ll have to get used to a new Mille Lacs identity as a factory for northern pike and smallmouth bass.