August 30, 2005
BOONE - The Iowa Department of Natural Resources (DNR) has
confirmed that two zebra mussels were recently found in Clear Lake
near Methodist Camp. Further investigation of the area revealed no
"This sighting of zebra mussels is certainly cause for concern,"
said Kim Bogenschutz, the DNR's aquatic nuisance species program
coordinator. "But it is too early to tell if there is a reproducing
population in the lake or if this is an isolated incidence of a
couple individuals that were released into the lake."
Zebra mussels look like fingernail-sized clams. The D-shaped shells
have alternating light and dark bands, and most are less than one
Zebra mussels are native to the Caspian Sea region of Asia and were
introduced into the Great Lakes in the 1980s from ballast water of
oceangoing ships. They spread from the Great Lakes to the
Mississippi River and were first documented in the Mississippi River
in Iowa in 1992. Clear Lake is the state's first inland report of
Zebra mussels are filter feeders that attach to hard underwater
surfaces using fibers called byssal threads. In the case of large
infestations, they may interfere with aquatic food chains, kill
native mussels and clog water intakes. "There's no getting rid of
zebra mussels once they are in a lake or river," Bogenschutz said.
DNR biologists will continue monitoring Clear Lake to determine
whether there are more zebra mussels. Divers will search underwater
surfaces, and docks and hoists will be inspected for zebra mussels
as they are removed from the lake for the winter.
One thing is certain, Bogenschutz said, the sighting of zebra
mussels in an interior lake highlights the spread of invasive
species in Iowa waters. "The zebra mussels in Clear Lake probably
arrived on or in a boat that had picked up the mussels in an
infested waterbody," she said.
Young zebra mussels are microscopic and can be unintentionally
transported with water in live wells or bait buckets. Adult zebra
mussels can attach to boats, trailers and aquatic vegetation.
"People from all over Iowa and the Midwest visit Clear Lake. If they
come from an infested waterbody, they can unintentionally transport
zebra mussels, Eurasian watermilfoil, or other aquatic invasive
species if they do not take the proper precautions to prevent their
spread," Bogenschutz said.
Anglers and boaters can help prevent the spread of aquatic invasive
Inspect your boat, trailer, and equipment and remove visible aquatic
plants, zebra mussels, other animals, and mud before leaving a water
Drain water from bait buckets, livewell, bilge, transom, and motor
before leaving a water access.
Dispose of unwanted live bait and worms in the trash.
Spray/wash your boat, trailer, and equipment with high pressure or
hot water before going to other waters, OR
Dry everything for at least five days before going to other waters.
The DNR is requesting the help of anglers, boaters, and homeowners
in the search for zebra mussels in Clear Lake. If you see a zebra
mussel, please note its location and contact Jim Wahl, fisheries
management biologist, at 641-357-3517.