Higgins EyeLampsilis higginsii
The Higgins eye mussel (Lampsilis higginsii (Lea, 1857)) was originally distributed throughout the upper Mississippi drainage (from the confluence of the Ohio River to Minneapolis/St. Paul, MN). This species was one of the first freshwater mussel species to be declared endangered under the Endangered Species Act because of an estimate 50% reduction in its range. Since the original recovery plan developed in 1983, new research has extended the known range at the time of its listing by 180 river miles. During that time new threats were also discovered including the invasion by the zebra and quagga mussels. An updated recovery plan was prepared in 2003, written by Dan Hornbach. In the revised plan the impact of zebra mussels was considered so important that additional essential habitat areas (areas deserving special protection) were added for this species. Three of these areas are in the St. Croix River - Prescott, Hudson and Franconia.
More information regarding the factors that may have lead to the decline of the Higgins eye mussels can be found in the flyer produced by the Fish and Wildlife Service. A PDF copy of the flyer can be found here. The Recovery Plan for this species as a PDF is at Higgins eye pearlymussel recovery plan: first revision - PDF May 2004.