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- For information on Wisconsin's natural communities, contact:
- Ryan O'Connor
Natural Heritage Inventory Assistant Ecologist
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.
Species of Greatest Conservation Need
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 the Wisconsin Wildlife Action Plan.
|Caspian Tern||Sterna caspia||3|
|Common Tern||Sterna hirundo||3|
|Horned Grebe||Podiceps auritus||3|
|Bald Eagle||Haliaeetus leucocephalus||2|
|Black Tern||Chlidonias niger||1|
|Blue-winged Teal||Anas discors||1|
|Forster's Tern||Sterna forsteri||1|
|Great Egret||Ardea alba||1|
|Lesser Scaup||Aythya affinis||1|
|Snowy Egret||Egretta thula||1|
|Trumpeter Swan||Cygnus buccinator||1|
No mammals species were reported to be associated with this community by the Wildlife Action Plan
|Reptiles and Amphibians||Score|
|Banded Killifish||Fundulus diaphanus||3|
|Lake Sturgeon||Acipenser fulvescens||3|
|Greater Redhorse||Moxostoma valenciennesi||2|
|American Eel||Anguilla rostrata||1|
|Skipjack Herring||Alosa chrysochloris||1|
Please see the Wildlife Action Plan, Chapter 2.4 to learn how this information was developed.
The following Ecological Landscapes have the best opportunities to manage for , based on the Ecological Landscapes of Wisconsin Handbook.
|Central Lake Michigan Coastal||Major|
|Northern Lake Michigan Coastal||Major|
|Southern Lake Michigan Coastal||Major|
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.
Threats / Actions
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 (PCB’s) 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.
- 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.
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.