"The most immediate and damaging zebra mussel impact to the St. Criox River ecosystem will probably be to the native mussel populations," says project leader Pam Thiel, Winona Fishery Resources Office (FRO).
The St. Criox River harbors a fragile and diverse native mussel community of at least 42 species and provides habitat for the only known population of the federally endangered, winged mapleleaf (Quadrula fragosa) and one of the few reproducing populations of the federally endangered, Higgins Eye pearly mussel (Lampsilis higginsi). Numerous state endangered and threatened native mussel species also inhabit this National Scenic Riverway.
"The invasion of zebra mussels into the St. Criox River poses a very real threat of extirpation to extinction for some native mussel species," says Thiel. "To address this threat, the interagency St. Criox River Zebra Mussel Joint Task Force developed and implemented a monitoring plan in 1993 to provide early detection and determine the extent of zebra mussel infestation in advance of any resource management actions designed to respond to this threat. A similar monitoring effort will be conducted again this open-water season."
The St. Criox River Zebra Mussel Joint Task Force is comprised of members from the Service, the National Park Service, the US Army Corps of Engineers, the U.S. Coast Guard, the Minnesota and Wisconsin Departments of Natural Resources, the Minnesota and Wisconsin Sea Grant Institutes, the Minnesota-Wisconsin Boundary Area Commission, and the Northern States Power Company.
Monitoring includes both passive and active sampling. Passive monitoring involves the deployment of multi-plate polyvinyl chloride (PVC) artificial substrate samplers. Inspections of the plate samplers are made every other week from April to November for adult zebra mussels. Thirty-nine locations on the St. Criox and Namekagon Rivers, including all major marinas and public access sites, have been identified as zebra mussel monitoring stations. The Services Winona FRO is monitoring 19 locations below Taylors Falls, Minnesota and the National Park Service is sampling 20 sites above Taylors Falls.
Active monitoring involves a commercial diver who inspects pre-selected sites such as bridge piers, navigation buoys, and mussel beds. In 1993, active monitoring was conducted five times, and this summer diving will be utilized on four occasions. As with passive monitoring, all active monitoring observations have found no zebra mussels.
Spring 1992, seven tributaries have been monitored by volunteers with technical assistance and equipment provided by the Services Winona FRO. Five tributaries (Chippewa, Buffalo, Trempleau, Black, and La Crosse Rivers) are located in Wisconsin and two (Zumbro and Whitewater Rivers) are in Minnesota.
"Monitoring plays a vital role in understanding the nature of the threat to the aquatic ecosystem. Our most effective monitoring tools are the eyes of the public because they are constantly making observations of boats, docks, shorelines, and other structures. We enlist the assistance of the public to conduct informal monitoring and contact our office whenever they spot zebra mussels anywhere other than the Mississippi River," says Thiel. Individuals are encouraged to call the Winona Fishery Resources office if they think they have found a zebra mussel in a lake or a tributary to the Mississippi River. The phone number is 507/452-4390.
The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 93-million-acre National Wildlife Refuge System which encompasses more than 530 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 66 national fish hatcheries, 64 fishery resource offices and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies. For further information about the programs and activities of the U.S. Fish and Wildlife Service in the Great Lakes-Big Rivers Region, please visit our home page at: http://midwest.fws.gov
