New findings confirm zebra mussels in
DNR biologists have found two more adult zebra mussels
in Lake Monona.
The new finding, in combination with one of the mussels
found last year, confirms that the exotic nuisance species
has arrived in Lake Monona, and probably in lakes Mendota
and Waubesa as well, said Kurt Welke, a Department of
Natural Resources fisheries biologist.
"This seals the deal," he said Thursday. "We found the
two with a minimum of effort. We thought there were more
zebra mussels in the Madison lakes and this tells me they
are now an established population. Now the Madison lakes
represent a source for zebra mussels to be transported
(by boaters) to other lakes."
The two mussels discovered this month were located near
the Monona Terrace Convention Center. The one found last
year was near Olbrich Park.
Given the estimated age of the mussels at two to three
years, Welke said they have likely been here for two or
three breeding cycles.
The small, fingernail-sized zebra mussels are native
to the Caspian Sea region of Asia. They were believed
to have been brought to the Great Lakes in ballast water
from a transoceanic vessel. They are now showing up in
In Wisconsin, zebra mussels have been found near the
shores of Lake Michigan, in 21 inland lakes, and in rivers,
including the lower Fox River and Oconomowoc River.
Zebra mussels don't pose a health risk to divers or swimmers
except that their sharp shells can make walking on them
The shells can make shorelines unusable and they produce
a stench as they decay and rot, Welke said.
"The nuisance mussels clog water-intake systems of power
plants and water treatment facilities as well as the cooling
systems of boat engines.
They also pose a threat to native mussel species. And
they filter microscopic plants and animals, which may
improve water clarity but might compete with native fish.
The DNR has begun posting inspectors at boat launches
along some popular Wisconsin waters in an effort to prevent
zebra mussels, Eurasian water milfoil and other invasive
species from spreading. The inspectors will talk to boaters
about the species and encourage preventive steps.
"They are not authorized to issue citations. Our challenge
now is to get the word out," Welke said.
Boaters are urged to drain bilge water and bait buckets
and remove aquatic plants on trailers or propellers before
leaving the water access area. They are also advised to
wash the boat, tackle, downriggers and trailer with hot
water when they return home.
Wardens could eventually issue citations in which fines
and court costs could amount to $120 for a first offense
and $145 for a second offense for launching boats or placing
boating equipment in navigable waters if aquatic vegetation
or zebra mussels are attached.