New Sightings in Wisconsin

From September, 1994 (update #22)

Zebra mussels were found for the first time in three inland Wisconsin lakes this summer. Moderate veliger densities were found in Okauchee Lake on a plankton sample taken July 22 by UW Sea Grant Advisory Services researchers. No additional veligers or adult mussels have been found in subsequent sampling of the 1,100-acre lake, including an August 10 diving survey conducted by Wisconsin Department of Natural Resources (WDNR) biologist Jim McNally and warden Gus Ernst. Okauchee Lake is upstream from the Oconomowoc River, which empties into the Rock River. The Elkhart Lake sighting was made July 31 by recreational diver Wyatt Wiehr, who found four mussels attached to a fishing rod recovered in 15 feet of water. Wiehr left the mussels with the Plymouth WDNR office for identification. Plankton samples and a WDNR dive survey turned up abundant veligers and adult mussels in the 286-acre lake. Wiehr made subsequent dives and found small numbers of mussels. On August 27 diver Bob Freedor collected zebra mussels at a depth of 17 feet in Racine Quarry, a 20-acre quarry located near the Root River a few miles from Lake Michigan. A follow-up investigation by WDNR biologist Steve Gallarneau turned up abundant mussels attached to a fishing pier along the quarry shoreline, and veligers were found in a plankton sample examined by Sea Grant personnel. Racine dive shop operator John Johnston of Reef Point Diving Center subsequently reported having observed zebra mussels in the quarry in 1993, perhaps as early as 1992. Although Racine Quarry has no public boat launch, Johnston said that he and other dive instructors from southeastern Wisconsin and northern Illinois regularly use the quarry for "check-out" dives and usually outnumber other water users. The quarry is located 40 yards from the Root River, a tributary to Lake Michigan. Anglers use a fishing pier and transport small boats to the quarry to catch stocked rainbow trout. The only prior inland zebra mussel sightings in Wisconsin were in the Mississippi River and a single sighting last September in Dairyland Reservoir on the Chippewa River. No additional mussels have been observed at the reservoir, and it appears unlikely that a population has become established there.

De PERE - Veligers were found in samples collected in the Fox River in early August seven miles from where the river enters the bay of Green Bay. A moderate density of veligers (1,500 per cubic meter) was collected in a plankton tow upstream, south of the DePere Dam. A similar density of veligers (900 per cubic meter) was also found at the same time on the north, downstream side of the dam, near Voyageur Park. Previous samples collected at these locations have not contained veligers. Four paper mills currently use water from the Fox River between the DePere Dam and its confluence with the bay of Green Bay.

ID: 199409-2.

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.