Fisheries, Midwest Region
Conserving the Nature of America

Winged Mapleleaf Mussel

The Winged Mapleleaf Mussel (Quadrula fragosa) was listed as a federally endangered species in 1991. It was once found in 13 states in river and stream tributaries to the Mississippi River where it lived on gravel or sand in riffles of clear, high quality water. Today it is only found in one river, the St. Croix River in Minnesota and Wisconsin. Its decline and restricted range is mainly due to changes in the ecology of the Mississippi River - especially the spread of the zebra mussel, an aquatic nuisance species. Zebra mussels become abundant and smother native mussels. Other factors that could lead to the decline of the winged mapleleaf mussel are contaminants and an increase in sediments.

In 2002, the La Crosse Fishery Resources Office, WI worked with the USGS- Upper Midwest Environmental Sciences Center (UMESC) in laboratory studies to identify the host fish necessary to complete the reproductive cycle of the winged mapleleaf mussel. This process involved locating gravid female winged mapleleaf mussels and working with a variety of fish in an attempt to identify the host fish. Divers searched for gravid female mussels and Genoa National Fish Hatchery, WI and the UMESC provided fish for testing. Very few gravid female mussels were found and it is hoped the project will contine in 2003. The University of Minnesota is also investigating host fish for the winged mapleleaf mussel.

For more information on the winged mapleleaf mussel view the Endangered Species Fact Sheet or Species Profile.