Fish Tags Covered with Mussels

From June, 1994 (update #21)

GREEN BAY, Wis. -- Zebra mussels were found attached to thin plastic tags implanted in three northern pike caught this spring in southern Green Bay. Two of the tags were returned to Wisconsin Department of Natural Resources (WDNR) personnel without the attached mussels, but the third tag was returned with at least 40 intact mussels. The mussel-encrusted tag was retrieved from a 33-inch northern pike caught just south of Longtail Point. The fish was tagged two years ago near DePere Dam in the Fox River. The tag became detached as the fish was brought up through a hole in the ice, according to Dan DuBois, who caught the fish. WDNR fish manager Terry Lychwick said zebra mussels on fish tags could produce problems estimating northern pike exploitation rates. Other than fish mortality, any factor that causes tags to fall off jeopardizes the WDNR's ability to estimate vital population parameters. Another concern is whether fish are impaired by mussel-covered tags. Northern pike are slow-moving "lie-and-wait" predators, which might increase their contact with settling zebra mussels. While fish fins and scales can shed settling mussels, a fish tag offers a suitable substrate. Lychwick said that more walleye than northern pike have been tagged in Green Bay, yet no similar mussel-covered walleye tags have been reported. The WDNR will attempt to verify similar reports. Lychwick would appreciate information from other biologists using similar fish tags in zebra mussel-infested waters.

ID: 199406-4.

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.