Editor's Note

From July 28, 1992 (update #14)

Zebra mussels showed only low levels of reproduction in Wisconsin waters of Lake Michigan during June and July as compared to peak levels late in the summer of 1991, though an upward trend in mussel reproduction was evident in the last two weeks. Water temperatures during this period were consistently lower than last summer. No signs of zebra mussel reproduction were seen in Lake Superior and Lake Winnebago. From June 15 to July 27, zebra mussel larvae (veligers) were detected in 11 of 72 water intake and 17 of 59 harbor samples from Lake Michigan. Recently settled post-veligers were found on five of 31 substrate samples examined from that lake. The only locations at which veligers were detected regularly in water samples were southern Green Bay and Milwaukee harbor. Peak densities observed were about 110,000 per cubic foot (3,100/m3) in the Milwaukee area and about 10,000 per cubic foot (280/m3) in southern Green Bay. During the same period, no veligers or post-veligers were found in eight water intake, 18 harbor and 42 substrate samples collected from Lake Superior. Nor were any veligers found in 10 plankton net samples from Lake Winnebago.

ID: 19920728-1.

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.