Located in the
Lyman F. Anderson
5201 Fen Oak Drive
Madison, WI 53718-8827
Map to Fen Oak
The zebra mussel is a tiny (1/8-inch to 2-inch) bottom-dwelling clam native to Europe.
The mussel takes its name from its striped shell. Zebra mussels were introduced into the
Great Lakes system in 1985 or 1986 and first turned up in Lake St. Clair. They were first
found in Wisconsin waters of Lake Michigan in 1989. Zebra mussels have been found on Lake
Monona and are likely in Mendota and Waubesa.
The exotics clog water-intake systems of power plants and water treatment facilities, along
with the cooling systems of boat engines. According to the Dane County Fisheries Biologist,
Kurt Welke, their presence can also damage the aquatic ecosystem. They can severely reduce
and may eliminate native mussel species. Because they filter plankton (microscopic plants
and animals) from the surrounding water, water clarity may improve, but the long-term
effects aren't well understood at this time. Newly hatched larval fish need zooplankton
and phytoplankton to survive and zebra mussels, which are incredibly efficient filterers,
are competing with native fish for the same food source. Ironically, even though zebra
mussels filter out many planktonic species, the nuisance blue-green algae - often the
summer bane of the Madison lakes - is not one of them. In simple terms, zebra mussels take
out the good stuff, but not the bad stuff.
Four species of carp native to Asia (grass, black, bighead and silver) have been introduced
to North America. Among these Asian carp, the bighead and silver have gained recent notoriety.
Both species have established large populations and impacted native fishes in the Mississippi
and Illinois Rivers, and are moving north toward Lake Michigan. It is possible that the silver
carp is already in Wisconsin.
Eurasian Water Milfoil is a submersed aquatic plant native to Europe, Asia and northern
Africa. It is one of eight milfoil species found in Wisconsin and the only one non-native
to the state. It first showed up in Wisconsin's counties in the 1960's and in the past
three decades, has expanded its range to about 310 lakes including seven lakes in Dane
County (Crystal Lake, Fish Lake, Kegonsa Lake, Mendota Lake, Monona Lake, Waubesa Lake,
Because of its potential for explosive growth and its incredible ability to regenerate,
Eurasian watermilfoil can successfully outcompete most native aquatic plants, especially
in disturbed areas. In a number of Wisconsin lakes, Eurasian watermilfoil has formed huge
monoculture stands with vast mats of surface foliage that shade-out native aquatic plants
and diminish the aesthetic beauty. Recreational activities like swimming, boating and sport
fishing are also diminished on Wisconsin lakes infested with Eurasian watermilfoil.
For pictures and info refer to the
field guide to aquatic plants and animals.
Boaters using Wisconsin waterways can help prevent transporting exotic plants and animals
from one lake or river to another by taking the following precautions with their boats and
The Yahara Waterways Water Trail Guide is a great resource for exploring our area waters.