First Non-hitchhiking Mussel Sighted in St. Croix River

From September, 1996 (Update #28)

Despite unparalleled boater restrictions to keep the St. Croix National Scenic Riverway free of zebra mussels, two adult zebra mussels - the first zebra mussels to be found on a substrate other than a boat - were found in mid-August in the St. Croix River near Stillwater, Minn., according to Sue Jennings, a St. Croix National Scenic Riverway resource management specialist. The zebra mussels were found near a sandy beach where boaters park their boats. Jennings speculated that the zebra mussels were dislodged from a boat. Divers from several cooperating agencies had been regularly inspecting about 20 other sites, including piers, pilings and native mussel beds, without finding any other zebra mussels. For several years the National Park Service, the U.S. Fish and Wildlife Service, and the Minnesota and Wisconsin Departments of Natural Resources have conducted a boater inspection and education effort to keep zebra mussels out of the St. Croix National Scenic Riverway to protect a unique fauna of native mussels, including the winged mapleleaf, a federally endangered species. For the first time this summer as part of this effort, boats on the St. Croix were randomly inspected by agency divers. New Minnesota and Wisconsin laws give state inspectors the authority to fine owners if attached zebra mussels are found on their boats. As of late August, two boats required cleaning after 30-40 zebra mussels were found attached to their trim tabs. Both boats had been harbored on the St. Croix in Afton, Minn., about 15 miles upstream from the river's confluence with the Mississippi River. Both contaminated boats were wintered in bubbler systems, which, Jennings speculates, may have contributed to the presence of zebra mussels on these boats. Boaters should pay particular attention to trim tabs as an area likely for zebra mussel attachment, Jennings advises. For further information, contact Sue Jennings, phone (715) 483-3284, email SACN_Resource_Management@nps.gov.

ID: 199609-3.

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.