Other Wisconsin Sightings

From September 10, 1991 (update #10)

GREEN BAY -- A spate of sightings of veliger and attached adults during August indicates that zebra mussels have infested the southern end of Green Bay, Lake Michigan. Because of its shallow, algae-rich and relatively warm waters, some biologists fear Green Bay could become as heavily infested as Lake Erie, where mussel concentrations have reached into hundreds of thousands per square yard. The latest sightings began July 31, when 13 zebra mussels were found attached to the outer housing of the circulating water pump for Wisconsin Public Service's Pulliam power plant at the mouth of the Fox River. The mussels ranged from one-fourth to one inch in size (0.6-2.7 cm). In early August, Wisconsin DNR biologist Dave Bougie found two zebra mussels attached to a buoy in southern Green Bay within a mile (1.6 km) of the mouth of the Fox River and the Port of Green Bay. Both mussels were just under a third of an inch long (<8 mm). Then, on Aug. 14, five mussels were found attached to Zebra Mussel Watch substrate samplers at Bayshore County Park, about 10 miles (16 km) north of the city of Green Bay. They ranged in size from 0.03 to 0.09 inches (0.8-2.3 mm) and numbered about 1,292 per square foot (120/m2). The samplers had last been examined four weeks previously. No mussels were found on the same samplers two weeks later. The first zebra mussel veligers observed in the bay were found Aug. 29, when Watch personnel detected a low density of 75 veligers per square foot (7/m2) in a plankton sample taken at Bayshore Park. That same day, Zebra Mussel Watch Assistant Coordinator Jory Jonas found three mussels attached to an anchor line for an oxygen meter at the Angle Lighthouse five miles (8 km) north of the Fox River entrance to the bay. On Aug. 30, recently settled mussels were found on substrate samplers at the Wisconsin Public Service's Pulliam power plant.

KENOSHA -- Zebra mussel veligers here were first detected in water samples collected from Kenosha Harbor on July 31. Substrate samplers examined the same day had no settled post-veligers, but two weeks later harbor water sample densities had increased to 35,314 per cubic foot (1,000/m3), and settled mussels were found on substrates at densities of around 500 per square meter. By Aug. 28, the number of zebra mussels on the substrate samplers had nearly tripled to 15,070 per square foot (1,400/m2). Veligers were also detected for the first time in water intake samples from the WEPCO Pleasant Prairie power plant on Aug. 7 and in those from the Kenosha Water Utility on Aug. 14.

RACINE -- Zebra mussel veligers were found for the first time on July 31 in water samples analyzed by Racine Water Utility personnel. Utility personnel detected increasing densities of veligers through Aug. 16, starting at levels around 4,238 per cubic foot (120/m3) and reaching 44,143 per cubic foot (1,250/m3) by the 16th. An upwelling of cold water (60*F/16*C) decreased veliger for the next two weeks, then densities jumped back, increasing to 5,200/m3) with a sudden increase 10*F jump in water temperature Sept. 3. Zebra Mussel Watch personnel found veligers in every water intake and Racine Harbor water sample they analyzed during August. Recently settled veligers were found Aug. 14 on Racine area substrate samplers at densities of 1,884 per square foot (175/m2); when checked again Aug. 28, the density had jumped to nearly 4,306 per square foot (400/m2). Scuba diver John Ames found a single zebra mussel 3/4-inch (19.1 mm) long in early August attached to a detached anchor near the south tip of the breakwater at the harbor entrance. In mid-August, diver Steve Hoeb said he found "zebra mussels everywhere" on rocks near the Racine Water Utility intake. The mussels ranged in size from 0.3 to 1.0 inches (6.5-25 mm).

PORT WASHINGTON -- Zebra mussel veligers were detected for the first time on Aug. 21 in both harbor water samples and water intake samples from the Port Washington Water Utility. The discovery could speed along the city's approval of a proposed $239,000 mussel defense system for its water intake pipes.

SHEBOYGAN -- A diver found mussels at densities of around 0 per square yard (6/m2) in mid-August near the intake for the Edgewater Generating Station, according to Wisconsin Power & Light Co. Production Engineer Dan Everson. Some of these mussels were as large as 1.2 inches (3 cm).

MANITOWOC -- Low densities of zebra mussel veligers were found Aug. 30 in plankton tows of Manitowoc Harbor waters by Zebra Mussel Watch scientist Hans Pearson of Silver Lake College.

ID: 19910910-3.

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.