Zebra mussels attached to hard substrate.

Under the guidance of the Ashland National Fish and Wildlife Conservation Office (NFWCO), Jeremy Bates, a student at the University of Wisconsin (UWS)-Superior and a Wisconsin Sea Grant volunteer, inspected a total of 16 boat hulls as the vessels were being lifted from Wisconsin waters of Lake Superior for winter drydock.  The vessels spanned six marinas from Bayfield to Port Wing, Wisconsin, a distance of 36 miles.  Unidentified snails were collected from three vessels, and identification of the snails is pending.  In addition, the managers of the marinas of Ashland and Washburn, Wisconsin, reported no mussels or snails observed on over 30 vessels lifted at their marinas.

Typically, Lake Superior does not contain sufficient calcium content for zebra and quagga mussels to become established, but the discovery of two zebra mussels in the mouth of the Amnicon River, Wisconsin, during the fall of 2007, and increased warming of Lake Superior waters encouraged the Ashland NFWCO to initiate limited mussel and snail surveillance in Wisconsin waters of Lake Superior.  The Amnicon River is a Lake Superior tributary, 10 miles east of the Duluth-Superior Harbor, the only location in Lake Superior where zebra mussels are established.  Dr. Mary Balcer, director of biological research at UWS, expressed concern that higher temperatures in Lake Superior for longer periods of time may help invasive mussels to survive longer.  This observation coupled with private vessel traffic between Ashland, Wisconsin, and the Duluth-Superior Harbor has also stimulated renewed interest in invasive mussel and snail monitoring by the Ashland NFWCO.