Sightings in Wisconsin

From December 17, 1993 (update #19)

SUPERIOR-In early November divers found low densities of zebra mussels (less than 0.3 per square meter) attached to breakwalls and pilings in Superior- Duluth Harbor, according to University of Wisconsin-Superior biologist Mary Balcer. By contrast, a large number of mussels was found near an ore dock. These zebra mussels were found in moderate densities ranging from approximately 50 per square meter near the surface to more than 130 per square meter at a depth of eight meters.

Balcer speculated that this colony could have become established by veligers released from a ship's discharged ballast water. She plans to investigate whether this colony can successfully reproduce.

LOWER FOX RIVER, GREEN BAY-No zebra mussels were found on navigation buoys retrieved November 3 from the Fox River between the DePere Dam and Fort Howard Paper Mill, according to the U.S. Coast Guard. (During this summer's Zebra Mussel Watch, barely detectable densities of veligers were found in plankton tows on one occasion in the same area.) The buoys were located about five miles upriver from mussel-infested waters in the bay of Green Bay.

In early November, the U.S. Coast Guard Aids-to-Navigation Unit removed similar buoys from the mouth of the Suamico River. At that time, the Coast Guard reported that the buoys were heavily encrusted with zebra mussels.

LA CROSSE-Zebra mussels were found for the first time in early October at the Northern States Power (NSP) French Island power plant, according to NSP instrument and control technician Bill Metcalf. Mussels had previously been reported at several Dairyland Power stations along the Mississippi River in southwestern Wisconsin.

By contrast, no zebra mussels have turned up at eight other NSP power plants in Minnesota, according to senior biologist Ken Mueller. Six of these stations are located on the Mississippi River. The other two are located on the St. Croix and Minnesota rivers a few miles from the Mississippi. Mueller said he was surprised that no mussels have been found in these upper Mississippi River system power plants. Zebra mussels have been regularly found attached to locks and dams in that region for the past two years.

ID: 19931217-2.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.