Mille Lacs Lake: Building a sustainable future

View Mille Lacs: A System Under Change
View a 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.


DNR At Work

Changes & Impacts

Lake FAQ

Newsletter

2015 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 2015 season.


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.

Bedrock

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

Boulders

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.

Click a question to view or hide the answer

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.

Hooked On Mille Lacs

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