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Rare animals
Find rare and non-game animals.
Rare plants
Learn about plants on the Natural Heritage Working List.
Rare lichens
Discover Wisconsin's lichens.
Natural communities
Explore Wisconsin's natural communities.
Other features
Discover unique resources.
Contact information
For information on Wisconsin's natural communities, contact:
Ryan O'Connor
Natural Heritage Inventory Assistant Ecologist

Lake Michigan


General natural community overview

Lake Michigan is among the largest and deepest lakes in the world. This massive waterbody covers 22,300 square miles and has 407 miles of coastline in Wisconsin. The lake is primarily cold water with summer maximum water temperatures below 22 degrees Celsius. Lake Michigan is relatively infertile, although it is warmer and more fertile than Lake Superior. Historically, the fish fauna consisted primarily of lake trout, ciscoes/whitefishes (Salmonidae), and sculpins (Cottidae). Warmer and more fertile harbors and bays (e.g., Green) had a more diverse assemblage of cool and warmwater fishes, especially in the family Percidae. Invasion by the sea lamprey due to commercial alterations of the Great Lakes waterways led to the first large-scale disruption of the biotic community, greatly depleting the native lake trout population. By the 1970's, three cisco species were extinct, and three others extirpated from Lake Michigan. (Only Lake Superior supports populations of two of these extirpated species, and only Lake Huron supports the third.) Over-harvest and other factors caused a steep decline in the population of lake herring. Now the biota is dominated by introduced or invasive non-native species, including Pacific salmon and trout, alewife, rainbow smelt, ruffe, white perch, gobies, zebra mussel, and exotic zooplankton.

Rare animals

Species of Greatest Conservation Need

Note: The information presented here comes from the 2005 Wisconsin Wildlife Action Plan. The 2015 revision has been submitted to the U.S. Fish and Wildlife Service for approval. Our website content will be updated when the plan has been approved.

The following Species of Greatest Conservation Need are listed according to their level of association with the natural community type, based on the findings in Wisconsin's 2005 Wildlife Action Plan.

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Caspian TernSterna caspia3
Common TernSterna hirundo3
Horned GrebePodiceps auritus3
Bald EagleHaliaeetus leucocephalus2
Black TernChlidonias niger1
Blue-winged TealAnas discors1
CanvasbackAythya valisineria1
Forster's TernSterna forsteri1
Great EgretArdea alba1
Lesser ScaupAythya affinis1
OspreyPandion haliaetus1
RedheadAythya americana1
Snowy EgretEgretta thula1
Trumpeter SwanCygnus buccinator1

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."

No mammals species were reported to be associated with this community by the Wildlife Action Plan

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Reptiles and AmphibiansScore
MudpuppyNecturus maculosus3

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Banded KillifishFundulus diaphanus3
Lake SturgeonAcipenser fulvescens3
Greater RedhorseMoxostoma valenciennesi2
American EelAnguilla rostrata1
Skipjack HerringAlosa chrysochloris1

Please see the Wildlife Action Plan, Chapter 2.4 to learn how this information was developed.


Management Opportunities

The following Ecological Landscapes have the best opportunities to manage for , based on the Ecological Landscapes of Wisconsin Handbook.

Map of the Ecological Landscapes of Wisconsin.

Major (3 on map)
A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important (2 on map)
Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present (1 on map)
The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.


Note: The information presented here comes from the 2005 Wisconsin Wildlife Action Plan. The 2015 revision has been submitted to the U.S. Fish and Wildlife Service for approval. Our website content will be updated when the plan has been approved.

These threats and priority conservation actions were identified for the community type in Wisconsin, and they apply to all of Wisconsin's Ecological Landscapes unless otherwise indicated. Please see the Wisconsin Wildlife Action Plan, Chapter 3.3 , for more information


  • Exotic aquatic species alter aquatic habitats, food webs and species interactions, and may have played and still be playing a role in the dramatic reductions seen in both yellow perch populations and in the lack of lake trout reproduction.
  • Development and urbanization of harbors and river mouths is causing degradation and loss of wetland and aquatic habitats.
  • Pollution from industrial micro-contaminants such as polychlorinated biphenyls (PCBs) is making fish unsafe to eat.
  • Dams on tributaries block fish migrations.
  • Poor watershed land-use practices are degrading nearshore and tributary habitat and water quality.
  • Overfishing (now largely controlled and regulated) had historically depressed populations of lake trout and lake herring.

Conservation actions

  • Various treaties, institutions, and citizen groups exist to help manage biodiversity in Lake Michigan, and these resources should be called upon to assist with management for Species of Greatest Conservation Need.
  • Improve regulations and education to prevent the introduction of additional exotic species and slow the spread of existing aquatic invasive species.
  • Protect and restore harbor and river mouth shoreline and wetland habitats, as is being done in the ongoing restoration of the Menominee River valley and estuary (Milwaukee County).
  • Work to reduce or eliminate and remediate sources of micro-contaminants.
  • Remove dams (as has been accomplished with the North Avenue Dam (Milwaukee County)) or install effective fish passage at dams.
  • Improve watershed land-use practices to reduce non-point source pollution.
  • Continue application of effective fisheries management, including ongoing efforts to restore the lake sturgeon population in the Milwaukee/Menominee rivers and estuary (Milwaukee County). The early 21st Century drop in alewife numbers may pose an opportunity to revitalize natural lake trout reproduction and to restore self-sustaining yellow perch and lake herring populations.




Dolomite pavement ("Great Lakes Alkaline Rockshore") on Hog Island, part of the Grand Traverse Islands Archipelago north of the Door Peninsula.

Photo by Emmet Judziewicz.


Fish Island is Wisconsin's easternmost point of land. This unvegetated island is composed mostly of dolomite cobbles.

Photo by Emmet Judziewicz.


Aerial of the Eagle Bluff an outcrop of the Niagara Escarpment along Green Bay. Peninsula State Park, Door County.

Photo by Eric Epstein.


Great Lakes Alkaline Rockshore and Boreral Forest, south end of Toft Point, Door County.

Photo by Eric Epstein.


Shallow bay of Lake Michigan, Great Lakes Alkaline Rockshore, mixed borealXnorthern hardwoods forest. Northern Door Peninsula.

Photo by Eric Epstein.

Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.

Last revised: Thursday, September 24, 2015