The same shortage likely caused the high walleye catch rate on Mille Lacs last summer.

Here are other considerations DNR fisheries scientists and managers weighed in considering Mille Lacs walleye angling restrictions this spring and early summer:

— Mille Lacs no longer supports dependably regular strong year classes of walleyes. Abundant now are 2013 and 2017 year classes, with the 2021 and 2022 classes showing promise. But given cannibalism and other factors affecting young Mille Lacs walleyes, a year class isn't considered "safe" until age 3.

— Mille Lacs is no longer as fertile as it once was. Septic and other effluents flowing into the lake became cleaner beginning in the mid-1990s, and zebra mussels showed up in 2005, with spiny water fleas following in 2009. The lake is clearer as a result, and less fertile, reducing energy available to the lake's other critters, including walleyes.

— The DNR has no idea how quickly Mille Lacs will warm up this summer. If the state's early spring morphs into an early, warm summer, walleye release mortality will increase, which must be included in anglers' estimated harvest. Also unknowable is whether the summer's weekend weather will be stormy or pleasant. The former restricts angler activity, the latter encourages it.

— The DNR can't estimate the size of this year's yellow perch hatch until June. If it's good, Mille Lacs walleye fishing success likely will decline, which could increase DNR harvest options. If not, continued high harvest rates — and continued restrictions — are likely.

In the end, anglers can choose to believe fish and wildlife management science developed by professionals — or not.

Either way, as a wise fellow once said, "The good thing about science is that it's true whether or not you believe in it."

©2024 StarTribune. Visit startribune.com. Distributed by Tribune Content Agency, LLC.