Panel of national fisheries experts to study Mille Lacs walleye issues

Mark Koivula of Duluth holds a walleye he caught in July 2013 on Mille Lacs Lake. (News Tribune file photo)

The Minnesota Department of Natural Resources will convene a blue-ribbon panel of national fisheries experts to review past and current management practices as part of an effort to increase Mille Lacs Lake’s walleye population, the agency announced today.

“We will have nationally recognized fisheries experts review our work and offer recommendations,” said Don Pereira, DNR fisheries chief. “We want the lake back on track. This is one strategy to do that.”

Panel members are: Drs. Jim Bence and Travis Brenden, Quantitative Fisheries Center at Michigan State University; Dr. Paul Venturelli, University of Minnesota; Dr. Nigel Lester, Ontario Ministry of Natural Resources and the University of Toronto; and Dr. Lars Rudstam, Cornell University and Oneida Lake Field Station.

Mille Lacs, a 132,000-acre lake in central Minnesota, is long-favored by anglers due to its abundant walleye population. However, the walleye population has been in decline for a number of years. Pereira said a key problem is the vast majority of walleye that hatch but do not survive to their second autumn in the lake.

He said that while the lake continues to have adequate walleye spawning stock and more than enough egg production and fry to repopulate the lake, the lake hasn’t produced a strong year-class of walleye since 2008.

To further help solve the problem, Pereira said the agency intends to contract with a nationally recognized fisheries expert to do an intensive review of the state’s fish tagging and fishing population estimates.

These reviews, combined with a new predator diet study to determine impacts on small walleye survival and fishing regulations that aim to protect young walleye, are all part of a systematic approach to improve walleye fishing, Pereira said. The diet study also includes winter sampling of predator fish under the ice.

The DNR acknowledges that state and tribal fisheries management has played a role in the decline, but long-term solutions will involve better understanding an evolving system that now has clearer water, a variety of unwanted aquatic invasive species, growing walleye predator populations and decreasing prey populations, such as perch and tullibee.

Water clarity on Mille Lacs has nearly doubled since the mid-1980s. Improvement began about 25 years after the implementation of the federal Clean Water Act in the early 1970s and has trended sharply upward since zebra mussels were discovered in the lake in 2006. Improved water clarity has been linked to movement of young of the year walleye off-shore at smaller sizes, and may also have benefited sight-feeding fish that prey on walleye and perch, fisheries officials say.

Northern pike and smallmouth bass populations have risen significantly since the early 1990s, biologists say. In 2013, the northern pike population increased to the highest level ever observed. The 2013 smallmouth bass population was the second-highest ever recorded. Smallmouth bass populations have been on the increase throughout Minnesota and Canada.

Once devoid of aquatic invasive species, Mille Lacs now contains zebra mussels, spiny water fleas and Eurasian watermilfoil. While it’s unknown exactly what implications these infestations are having, it’s suspected the increase in milfoil is providing more ambush cover for northern pike. Also, water-filtering mussels are contributing to water clarity that allow more aquatic vegetation to grow at deeper depths and in more dense stands.

Guides and residents on the shores of Mille Lacs Lake have heard all the DNR’s theories about the lake’s walleye decline and have seen the data, said Bob Carlson of Isle, who has been guiding for nearly 20 years on the lake.

He and many other residents believe the problem is treaty-affirmed netting by Chippewa bands rather than clearer water, pike predation or the lack of young walleye survival.

“You don’t need experts to see what’s going on,” Carlson said. “Since tribal netting has started, the population has been going down… When you go to the buffet and scoop in the pan long enough, it’s going to run out.”

DNR fisheries biologists say, while Chippewa netting and angler harvest both influence the fishery, anglers are still taking more walleyes and more little walleyes than tribal netters. But some Mille Lacs Lakes residents like Carlson allege that not all of the tribal harvest is being documented.

 

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