Why Mille Lacs fishery faltered, and what we can do

Dick Sternberg didn't predict Mille Lacs walleyes would collapse when he wrote his first analysis of the lake's condition and management in 2003. But he did say 12 years ago that management of the lake, if not changed, likely would contribute to a marked downfall of Mille Lacs walleyes.

Which is what has happened, with Department of Natural Resources (DNR) Commissioner Tom Landwehr announcing Tuesday the strong likelihood that this year's minimalist Mille Lacs sportfishing walleye quota of 28,600 pounds might be exceeded by month's end.

If that occurs, walleye fishing on the big lake will end until at least Dec. 1.

Sternberg is a onetime DNR fisheries biologist whose Mille Lacs walleye management analysis was largely dismissed by the DNR.

In part this was due to bureaucratic parochialism, and in part it was because Sternberg undertook his data review at the request of PERM, or Proper Economic Resource Management, a group whose slogan is "Ban the gillnet.'' Consequently, some viewed Sternberg's work as an anti-netting hit job. It wasn't.

In fact, a review of Sternberg's study underscores that he pointed out what DNR fisheries managers have discussed more forthrightly only recently: that cannibalism of young walleyes by older and/or bigger fish, including older walleyes, might be the biggest Mille Lacs problem.

What's more, the DNR's continuation of tight harvest sportfishing slot limits in the years since likely has contributed to, if not solely resulted in, the lake's present-day imbalanced (measured by age and size) walleye fishery.

Consider the following, which Sternberg published in 2003:

"All [Mille Lacs] walleye year-classes since the year 2000 have been well above average, with the strongest year class coming in 2001. But in the case of both the 2000 and 2001 year classes, the numbers were seriously depleted by the time the fish reached a year of age, most likely as a result of predation by the increasing population of large walleyes.

"In fact, the exceptionally strong 2001 year class went from 225 percent above average to 98 percent below average within one year. … As the situation now stands, future walleye fishing in Mille Lacs depends greatly on the 2002 year class and possibly the 2003, assuming it does not meet the same fate as the 2000 and 2001 year classes.

"Conclusion: As long as the Mille Lacs walleye population remains heavily skewed toward the larger size classes, the threat of heavy cannibalism of young-of-the-year walleyes will persist.''

Now consider this, from an interview I did with DNR fisheries chief Don Pereira in 2014.

Question: What's the status of Mille Lacs walleyes?

Pereira: We have an abundance of spawning females. But there's an elevated mortality of young walleyes, and we're not sure why. Walleyes are in the lake in good numbers after the spawn, but they're not surviving in sufficient numbers as yearlings and 2-year-olds. … Our leading hypothesis is that they are probably dying from elevated predation.''

A few points:

• Co-management by the state and eight Chippewa bands of the lake's walleyes that began in 1998 and continues today has complicated that task beyond measure irrespective of whatever effect, if any, the bands' netting has on the lake's walleyes.

• In part this is because dividing the "safe allowable harvest'' of Mille Lacs walleyes between the two parties requires, first, an accurate estimate of the lake's walleye population and size distribution. Some observers question to what degree this is possible. To the extent that it isn't, if it isn't, harvest distribution and size and other management decisions flowing from it will be similarly inaccurate.

• Even if fisheries managers have accurately assessed walleye numbers and size distribution, the DNR and the bands nevertheless have continued to ignore the lake's growing predator/large fish problem or have mistakenly believed until recently that its effect on the lake's smaller walleyes is inconsequential. How else to explain the DNR's continuation of slot limits that encourage the harvest of the lake's smaller, rather than larger, walleyes?

• To reduce the number of big Mille Lacs walleyes, the DNR and the bands in the near future likely will have to agree to exceed the lake's safe allowable walleye harvest — a difficult but perhaps necessary decision to rebalance the lake.

What to do? Start here: The governor and key legislators should tell the DNR that its Mille Lacs fisheries management meetings with the Chippewa no longer can be held in secret.

Rather, to ensure from this point on that the public knows firsthand the nature, context and agreed-upon definitions of data being used to make management decisions, these get-togethers should be open to the public.

And should have been long ago.

Dennis Anderson • danderson@startribune.com