Lake Mille Lacs is Minnesota's own Rubik's Cube: a walleye fishery puzzle that seems impossible to solve.
The complexity came to a head this fall when the Department of Natural Resource's gill-net surveys showed a declining number of male walleyes in the big lake, as well as a drop in the overall walleye population to the lowest levels in 40 years. And the lake's larger walleyes are getting skinny, a sign they are not finding enough food.
Think you have the answer? Before you say yes, consider:
The walleye fishery is co-managed to serve thousands of sports anglers, local fishing and tourism-related businesses and Chippewa tribes, who net fish each spring.
Sharing the walleye harvest means regulations for sports anglers that require them to release larger fish, altering the composition of the fishery.
The bands' nets, too, tend to target smaller walleyes.
Smallmouth bass have become much more abundant, as have northerns, changing the dynamics of the fishery and potentially impacting the forage base.
The invading zebra mussel population has exploded, causing unknown effects.
Recent warming trends appear to be causing more frequent dieoffs of tullibees, a cold-water species that walleyes eat.
DNR and Chippewa fisheries researchers now are assessing the accuracy of DNR survey data, which, if correct, could lead to more restrictive fishing regulations. And they must solve the puzzle by January, because that's when officials meet to determine the safe allowable walleye harvest for 2013 and the fishing regulations necessary to restrict harvest.
"I'm reasonably confident we'll know better what's going on in Mille Lacs [by then],'' said Don Pereira, DNR fisheries research and policy manager.
If both the DNR and tribal officials agree on what's happening, they can propose actions, Pereira said.
"The challenge is going to be: What can we do to fix it?'' he said. "That's the $64,000 question. Is there a practical thing that can be done that would preserve all the things the fishery supports, including the local economy and tribal needs to harvest fish?''
One critic of the state's management of Mille Lacs said he believes that the numbers are accurate, that they reflect serious problems and they will require drastic action.
"There's no valid reason to not believe the numbers,'' said Steve Fellegy, a Mille Lacs fishing guide who has long opposed the Chippewa's claim to off-reservation hunting and fishing rights that were affirmed by a 5-4 U.S. Supreme Court decision in 1999.
He said the walleye fishery is imbalanced because of years of tribal netting and the resulting restrictions on non-band anglers, which require larger fish to be released.
"You've created a high amount of big predator fish, so the forage base that used to sustain the fish population is too small,'' he said. "To be honest, I don't see how you can tighten regulations more than they already have,'' without causing anglers to go elsewhere.
"As extreme as it sounds, I wouldn't be against shutting the lake down to all harvest for two years'' to help the fishery recover, Fellegy said. But the state would have to subsidize Mille Lacs-area businesses to keep them afloat during the closure, Fellegy said.
However, Dick Sternberg, a former DNR fisheries biologist, said the opposite might be needed:
"If the forage base is in trouble, it seems you'd want to take more fish out of the lake,'' he said. Regulations protecting large fish, including walleyes, northerns, smallmouth bass and muskies, could be responsible for the lack of forage fish -- and small walleyes -- he said, agreeing with Fellegy on that point.
Sternberg said it makes sense for researchers to reexamine the DNR's gill-netting results. "It's hard to believe the [walleye] population declined that much in one year,'' he said.
Neither the DNR nor the bands are talking about policy issues or possible regulation changes until the science is confirmed.
"No conclusions have been reached -- it's still under investigation,'' said Sue Erickson, public information office director for the Great Lakes Indian Fish & Wildlife Commission (GLIFWC), which represents 11 Chippewa tribes in Minnesota, Wisconsin and Michigan. GLIFWC researchers have been reviewing the data with the DNR and outside researchers.
The January meeting between the DNR and the bands is closed to the public, a sore point for some, including Fellegy, who believes the meetings should be open. But state officials say they can be legally closed.
Meanwhile, DNR officials will meet in February with the Mille Lacs Input Group, a consortium of area resort owners, bait shops and other businesses, to review their findings and recommend fishing regulations for 2013.
Doug Smith email@example.com twitter: @dougsmithstrib