Mille Lacs Lake: Building a sustainable future

View Mille Lacs: A System Under Change
View an introductory presentation that explains what's happening at Mille Lacs Lake and what steps DNR is taking to restore the lake's renowned walleye fishery.

Improving Mille Lacs Lake's walleye fishery as expediently as possible with as little negative impact to the local community as possible is the state's primary goal.

The situation will not turn around for several years. It will take time – as well as careful management, monitoring and analysis – for enough smaller walleyes to grow into the larger walleyes that anglers prefer to catch and that can contribute to future reproduction.

Even so, Mille Lacs remains a quality sport fishery. In addition to high numbers of large walleye, excellent quality fishing exists for northern pike, smallmouth bass and muskellunge.

Time and experience have proven that Mille Lacs is a resilient multi-species fishery for the anglers of Minnesota and tourists beyond our borders. A combination of regulations friendly to small walleye and cooperation among all users now will build and enhance the long-term sustainability of the fishery.

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2014 regulations set

As part of a plan to increase angling opportunity, improve walleye numbers and stay within the state's 1837 Treaty safe harvest allocation, the Department of Natural Resources will modify fishing regulations at Mille Lacs Lake for the 2014 season.

"The new regulations reflect our commitment to improving the walleye fishery as quickly as possible with as little harm to the local economy as possible," said Don Pereira, DNR fisheries chief.

More liberal northern pike and smallmouth bass regulations speak to the fact these species can withstand additional pressure because their populations are at or near record highs. The current walleye regulation and extended night fishing ban will protect upcoming year classes of young walleye, adult spawning stock and help ensure the harvest stays within the safe harvest level. Reasons for the changes are explained on the Regs FAQ tab.

2014 Regulations

  • Walleye: Two fish 18-20 inches. One may be longer than 28 inches.
  • Northern pike: Ten fish. One may be longer than 30 inches. Angling season closes March 29, 2015.
  • Northern pike darkhouse spearing: Ten fish. One may be longer than 30 inches. Darkhouse spearing season closes February 22, 2015.
  • Tullibee (Northern Cisco): Possession limit is 10.
  • Bass: Total of six smallmouth and largemouth combined. One smallmouth may be longer than 18 inches. Season opens Saturday, May 10. Smallmouth are exempt from the mid-September catch-and-release regulation. Bass may be caught through Sunday, Feb. 22, 2015.
  • No culling: You may not release fish already caught and kept and replace them with other fish you catch even before you reach your daily or possession limit.

2014 safe harvest levels set

Walleye anglers on Mille Lacs Lake likely will see regulations similar to last year when the season opens on Saturday, May 10, based on the safe harvest level recently announced.

The 2014 walleye safe harvest level is 60,000 pounds. Of this amount, 42,900 pounds is allocated to the state and 17,100 pounds is allocated to the eight Chippewa bands with 1837 Treaty harvest rights. These allocation amounts were recently agreed upon at a meeting of DNR and tribal natural resource leaders.

A limited harvest under the existing restrictive harvest slot, combined with potential additional more restrictive regulations, will provide the needed protection to the lake's struggling walleye population.

The conservative allocations – the lowest since cooperative treaty management of the lake began in 1997 – reflect biologists' deep concern about the lake's recent inability to produce large crops of young walleye, despite adequate spawning stock and excellent production of young-of-the-year, fingerling-sized fish.

The Mille Lacs safe harvest level has ranged from a high of 600,000 pounds in 2006 to this year's low of 60,000 pounds. Actual harvests, however, have been very low in some previous years. In 2003, for example, state anglers took only 66,492 pounds of walleye and similar situations occurred in 2004 and 2008.

National review of management planned

Unprecedented change is occurring at Lake Mille Lacs and the Minnesota Department of Natural Resources is taking unprecedented actions to address it.

The agency will convene a blue-ribbon panel of national fisheries experts to review past and current management practices as part of a new effort to increase the legendary lake's walleye population as quickly as possible with minimal impact to the local community.

"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 Brended, 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.

Pereira said the agency is also contracting with an internationally recognized fisheries expert at Canada's Simon Frazer University 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.

Mille Lacs is not the same lake it used to be. Unprecedented changes are causing unexpected impacts. Learn more about how the lake is changing by clicking each item in the list below.

Clearer Water

More Predators

Aquatic Invaders

Food Competition

Fewer Tullibee

Water clarity

Water clarity 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. Zebra mussels were first discovered in Mille Lacs in 2006. They did not exist in great numbers until 2011, which corresponds with a sharp upward trend in water clarity during the past three years. Improved water clarity has been linked to movement of young of the year walleye off-shore at smaller sizes and also may have benefited sight-feeding fish that prey on walleye and perch.


Underwater photo of Mille Lacs Lake bedrock after zebra mussels.
Underwater photo of Mille Lacs Lake bedrock before zebra mussels.


Underwater photo of Mille Lacs Lake boulders after zebra mussels.
Underwater photo of Mille Lacs Lake boulders before zebra mussels.

Click each photo above to see underwater photos taken before and after zebra mussels infested Mille Lacs Lake. Note the difference in water clarity.

A northern pike

A northern pike

Increased predation

Northern pike and smallmouth bass populations have risen significantly since the early 1990s. 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.

Invasive impacts

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.

Underwater photo of native Mille Lacs Lake mussel after zebra mussels.
Underwater photo of native Mille Lacs Lake mussel before zebra mussels.

Before zebra mussels infested Mille Lacs Lake, cadis fly, snails and other native organisms co-existed with native mussels (left). Now, zebra mussels attach themselves to native mussels, displacing those symbiotic organisms. Native mussels, now with restricted feeding openings and competing with zebra mussels for the same microscopic food, eventually starve to death (right).

The aquatic food chain

The aquatic food chain

More competition for zooplankton

First detected in 2009, spiny water flea numbers have fluctuated but show no signs of declining. Spiny water fleas may be having a negative impact on the native zooplankton community by directly competing with small fish for food and altering the historic aquatic food chain.

Tulibee, also called cisco, have been a preferred food source for Mille Lacs Lake walleye.

A tullibee or cisco

Changes in key forage species

The most prominent change is a decline in tullibee, likely the result of warmer water temperatures. A decline in tullibee is likely negatively affecting walleye in Mille Lacs, especially larger walleye, as walleye grow significantly faster when they are able to feed on this species because it is higher in calories than other prey species, including yellow perch.

DNR has solicited the input of national and international fish experts as part of a broad approach to understand and improve the Mille Lacs walleye situation as quickly as possible without unwanted consequences to the local community. Click each name below to learn more about panel members.

Lars Rudstam

Jim Bence

Travis Brenden

Nigel Lester

Paul Venturelli

Jim Bence

Jim BenceA professor at Michigan State University and the co-director of the Quantitative Fisheries Center located there. A fish population modeling expert, Bence has developed harvest management strategy simulations for Lake Erie walleye. He has conducted professional reviews of Lake Erie yellow perch and walleye stock assessments, as well as ongoing collaboration on Saginaw Bay walleye assessments. Bence is a past president of the International Association for Great Lakes Research. He is familiar with Mille Lacs through previous reviews of management and stock assessment models.

Travis Brenden

Travis BrendenAn associate professor at Michigan State University and the associate director of the Quantitative Fisheries Center. Brenden has extensive experience with modeling and stock assessment of Lake Erie walleye and yellow perch fisheries. His work also extends to predator-prey dynamics, gillnet selectivity analysis and age-based stock assessment models, such as those used on Mille Lacs.

Nigel Lester

Nigel Lester

A research scientist with the Ontario Ministry of Natural Resources in Peterborough and an adjunct professor for the University of Toronto. Lester has extensive experience in the areas of walleye life history, sustainable fishing and estimating sustainable harvest rates. His experience studying the effects of light and temperature on walleye abundance and production will be extremely important in regard to the water clarity changes Mille Lacs has undergone beginning in the 1990s and continuing through the present.

Lars Rudstam

Lars Rudstam

A professor at Cornell University and the director of the Cornell Shackelton Point Biological Field Station on Oneida Lake, New York. Oneida is an important and historic walleye lake that has undergone extensive ecosystem and fish community change. These changes have been influenced by zebra and quagga mussels, cormorants and Eurasian watermilfoil. Rudstam's work on Oneida and the Great Lakes is very applicable to Mille Lacs in terms of system change, walleye and perch dynamics, zebra mussel impacts, and zooplankton dynamics.

Paul Venturelli

Paul Venturelli

An assistant professor at the University of Minnesota. Venturelli has extensive experience with walleye population dynamics and life history as they relate to sustainable fishing in Ontario. He also serves on the Red Lakes Technical Committee and has closely studied the effects of temperature, density, and harvest on walleye reproduction.

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What is happening at Lake Mille Lacs?

The aquatic system is undergoing significant change, including a declining walleye population. The vast majority of walleye that hatch do not survive to their second autumn in the lake. The DNR is initiating unprecedented actions in response to this unprecedented change. The agency wants to increase the walleye population as quickly as possible with minimal impact to the local community.

Why is this happening?

While state and tribal fisheries management has played a role in the decline, the persistent problem of promising walleye year classes that disappear year after year is also linked to system change. Changes include increased water clarity that benefits sight-feeding fish; the introduction of zebra mussels, Eurasian watermilfoil and spiny water fleas; significantly higher populations of smallmouth bass and northern pike that may prey on walleye; a changing zooplankton community that may be altering the aquatic food chain; and declines in certain forage species, including tullibee.

What is the DNR doing?

As part of a multi-pronged approach, the DNR will convene a blue-ribbon panel of national fisheries experts to review past and current management practices. These experts will review the DNR's work and offer recommendations. The agency will also contract nationally recognized fisheries expertise to do an intensive review the state?s fish tagging and fish population estimates. These reviews, plus new and more intensive field studies, are part of a systematic approach to improve walleye fishing.

What will this mean to anglers?

The agency will continue to implement regulations that protect young walleye. The lake has not produced a strong year class since 2008. That year class and upcoming year classes need to be protected to ensure there is adequate spawning stock in the future. Currently, there is adequate spawning stock, more than enough egg production and abundant fry production.

Anything else planned?

Details still are being finalized but DNR will explore new and innovative ways to engage citizen input on future management decisions; consider any feasible methods to manage aquatic invasive species; continue discussion and cooperation with tribal natural resource managers; and support a new Mille Lacs tourism marketing initiative with Explore Minnesota Tourism.

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Why was the night fishing closure extended through 6 a.m. Monday, July 21?

Normally, night fishing on Mille Lacs between 10 p.m. and 6 a.m. is closed from the Monday after the opener (May 12, 2014) until mid-June. The night closure, which was lifted beginning at 10 p.m. on Monday, July 21, was being extended through the end of the open water season (Dec. 1) this year to reduce the chances of going to catch-and-release only for walleye fishing. If the 2014 walleye harvest is projected to exceed the state's safe harvest level of 42,900 pounds at any point during the season, then catch-and-release only walleye fishing would be imposed through Dec. 1. No one wants that. This regulation is extra protection against catch-and-release only walleye fishing.

It is still possible that even with the extended night fishing closure, state anglers will exceed the walleye safe harvest level. That's because this year's walleye regulation (a limit of two from 18 to 20 inches, except one longer than 28 inches may be taken) has a 33 percent chance of being too liberal. The extended night fishing closure regulation reduces that potential for exceeding the safe harvest level to about 10 percent. But if a really hot walleye bite develops or unusually warm summer temperatures increase the mortality rate of walleye caught and returned to the water, the odds of going to a catch-and-release regulation increase.

DNR consulted with the Mille Lacs Fisheries Input Group and others and has decided that the level of risk with the existing regulation and the added assurance of the night closure extension is more acceptable than imposing even more restrictive walleye bag and/or slot limit regulations. The night closure begins at 10 p.m. (rather than a later time) because it's intended to reduce harvest. Pushing closure time to a later hour would defeat the intent of the regulation.

Will this regulation affect other anglers?

Yes. Most notably it will have implications for those muskellunge anglers who fish after dark. Though these anglers are not targeting walleye, it is an unworkable enforcement situation to have one subset of anglers on the lake after 10 p.m. while restricting others. Muskellunge anglers are being asked to accept this inconvenience as part of the larger effort to improve the walleye population as quickly as possible.

What is the rationale for the northern pike regulation change?

Like the new smallmouth bass regulations, new northern pike regulations are designed to increase angling opportunity and harvest, while maintaining an abundant population and trophy-sized fish. The new regulations are not intended to drive down the northern pike population. Instead they are designed to allow additional harvest by anglers for whom harvesting a meal of fish is important, and who might not fish Mille Lacs if they feel that harvesting a meal is unlikely.

The regulation was based on the following facts. Northern pike have been increasing in abundance since 1995. Young-of-year northern pike were at record numbers in 2012 and 2013. Many of the 2012 pike will be approaching sizes favored by anglers during the 2014 season, and could provide substantial harvest opportunity with little risk to the population. The 10-fish bag emphasizes the surplus nature of these smaller pike, and the one over 30 inches is to help conserve the valuable larger fish. The complete removal of the protected slot was to accommodate an increased opportunity to harvest fish by both angling and spearing. Northern pike grow very fast in Mille Lacs, much as they do in productive lakes of southern Minnesota. They can grow to 26 inches in only three years. Current research is underway to better understand the ecological impacts of elevated rates of northern pike production.

What is the rationale for the smallmouth bass regulation change?

Like northern pike, smallmouth bass numbers have been increasing. Their numbers began to grow possibly as early as the 1980s but certainly since the mid-1990s. In 2000, very conservative regulations (bag of 1, 21-inch minimum size) were put in place to protect what was thought to be a small and highly vulnerable smallmouth bass population. Since that time, the population has increased approximately sevenfold. The increase is more likely related to changing lake and environmental conditions (i.e. longer growing seasons, clearer water allowing more light penetration and vegetation growth) than to the protective regulations. If the 2014 smallmouth catch is similar to 2013, the harvest would be a very small portion of the overall population. Similar to northern pike, the one over 18 inch smallmouth bass regulation is to conserve the trophy quality of the fishery.

Can changes be made?

All Mille Lacs fishing regulations are reviewed annually and can be adjusted as needed if they do not perform as expected.

Hooked On Mille Lacs

A quarterly newsletter from the Aitkin Area Fisheries Office that focuses on Mille Lacs Lake.