Leda A. Cunningham, Daniel J. Hornbach, Mark C. Hove. Macalester College, Biology Department, 1600 Grand Avenue, Saint Paul, MN  55105

Increasing threats to the native mussel community in the St. Croix River (e.g. bridge construction, zebra mussel outbreaks) make it necessary to study the efficacy of relocating mussels to less-threatened parts of the river. To determine the effects of relocation on mussel growth and survival a three-year in situ experiment was conducted at Wild River State Park, Minnesota. In 1997 a 25 m2 study grid containing 25 cells was placed near the confluence of the St. Croix and Sunrise rivers (reference site), and another was placed at the eastern boat launch at Wild River State Park (relocation site). Each cell was randomly assigned one of the following treatments: (1) double resident mussel density, (2) addition of 10 pimplebacks, (3) addition of 10 spikes, (4) addition of 10 pocketbooks, and (5) control (no manipulation occurred during the first year). In 1997 mussels were collected from the reference site, placed into study grids, and individuals from the first four treatments were measured, weighed, and marked. In 1998 and 1999 mussels were measured and weighed. Those found without a number were recorded as "new" and marked, those missing from the 1998 census were logged as "missing", and the rest were logged as "recovered", "control", or "dead" as applicable to their status. Preliminary examination of data indicates no difference in growth or mortality between treatments. Mortality was low (5 %) compared to similar studies (Cope and Waller 1995). Results suggest that relocating mussels to similar habitats may be an effective strategy for conserving mussel populations living in potentially harmful parts of the St. Croix River.

Funding provided by the Minnesota Legislative Commission on Minnesota Resources.
 

Presenting author: Mark Hove, Macalester College, 1600 Grand Ave., St. Paul, MN  55105. Phone (651) 696-6827  FAX (651) 696-6443  e-mail Mark.Hove@fw.umn.edu