A task force appointed by the Great Lakes Fishery Commission found the ruffe to be a threat to North American fisheries and recommended a plan of research and control. The Aquatic Nuisance Species Task Force, a Federal board established by the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990, found the ruffe to be an aquatic nuisance warranting a control program and appointed a Ruffe Control Committee, chaired by the Service, to develop this strategic effort.
"The Ruffe Control Program, managed by the Service, is the first of its kind to be developed under authority of the Act, " says Tom Busiahn, Committee Chair and Project Leader for the Services Ashland, Wisconsin Fishery Resources Office. "We feel that we have a window of opportunity, if we act immediately, because the cold water of Lake Superior is unfavorable habitat for ruffe and has slowed its range expansion."
The ruffe (Gymnocephalus cernuus), a type of perch fish native to lakes and rivers over a broad area of Europe and Asia, is an exotic nuisance fish capable of explosive population growth. Because of its small size (4 to 6 inches in length), it has no value in the commercial or recreation fishing arenas. Ruffe became abundant within a decade of introduction into habitats in Scotland (Loch Lomond) and North America (western Lake Superior), while native fish populations sharply declined.
Ruffe were introduced to Duluth Harbor on Lake Superior through ballast water of an ocean-going freighter and were first collected in fish surveys in 1986. By 1991, ruffe were the most abundant fish in the 13,000 -acre harbor. They had spread eastward 55 miles to several estuaries on the south shore of the Lake, and were collected in Thunder Bay, Ontario, 180 miles to the northeast. The most likely culprit for transport from Duluth to Ontario was in the ballast tanks of a cargo ferry. By 1993, ruffe were more abundant than any other fish combined in the trawl samples from Duluth Harbor, and had spread 97 miles east of Duluth to the Bad River.
The potential range of the ruffe extends from the Great Plains to the eastern seaboard, and northward into Canada. Prime areas for colonization in the Great Lakes include Lake Erie, Lake St. Clair, Saginaw Bay, and Green Bay, all of which support major fisheries for walleye and yellow perch. If it colonizes southern Lake Michigan, the ruffe has access to the Mississippi River basin via the Chicago River.
The Ruffe Control Program has six components: (1) range reduction; (2) ballast water management; (3) predator evaluation; (4) population investigation, including biology and ecology; (5) surveillance, focusing on the movement and spread of the ruffe; and, (6) education. The Committees focus is comprehensive. It has recommended the development of educational and regulatory actions to prevent bait bucket transport. With Committee assistance, the maritime industry developed a ballast water management plan to reduce the risk that ships navigating the Great Lakes might transport the ruffe out of western Lake Superior. Additionally, the Program proposes to eliminate reproducing populations of ruffe, using chemicals to further prevent range expansion; research on ruffe populations and their effects on the ecosystem; and, surveillance to look for newly established colonies. Finally, the Control Program proposes a thorough evaluation of biological control measures undertaken by Minneosta and Wisconsin, in which these agencies sought to control ruffe by enhancing populations of predator fish.
"Ruffe control will depend on the use of chemicals, or piscides, in the near term, "says Busiahn. Ruffe are susceptible to all piscides registered in the United States such as rotenone, antimycin, TFM, and Bayluscide. "However," the aquatic pest managers toolbox is nearly empty, and integrated pest management is poorly developed for aquatic pests in open systems."
Under certain conditions of water chemistry, TFM, used to control sea lamprey, will selectively control ruffe. "A TFM treatment for sea lamprey control in the Brule River, Wisconsin, eliminated 97 percent of the ruffe population, with no significant mortality among native fish.
Over the long term, "stated Busiahn, "a bottom release formulation of antimycin may have the greatest promise of eradicating ruffe colonies in lakes and estuaries with minimal impact on other fish."
"The Ruffe Control Program should continue until ruffe expand their range beyond western Lake Superior, or until new information shows that the ruffe is not a threat to North American fisheries and aquatic ecosystems. If the ruffe escapes from western Lake Superior, the Program should be re-examined, and terminated if control appears to be unrealistic. Ultimately, the Ruffe Control Committee believes that the invasion of the ruffe is a symptom of larger problems of ecosystem health. Aquatic ecosystems with integrity and biodiversity may be more resistant to invasion by nonindigenous nuisance species, " Busiahn said.
The Great Lakes-Big Rivers Region of the U.S. Fish and Wildlife Service includes the states of Illinois, Indiana, Iowa, Michigan, Minneosta, Missouri, Ohio and Wisconsin.
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
