During a routine Eurasian ruffe surveillance survey in Lake Michigan waters off Escanaba, Mich., last week, U.S. Fish and Wildlife Service biologists captured and destroyed an adult Eursian ruffe. This is the first confirmed finding of a ruffe in Lake Michigan.
The Eurasian ruffe is an exotic invasive species first discovered in the Duluth, Minn., harbor and St. Louis River estuary of Lake Superior in 1986. Since then, ruffe numbers in the Duluth harbor have increased to become the most common species found while sampling with trawls. Their range has expanded into the Wisconsin, Michigan and Ontario waters of western Lake Superior, and to one location in Michigan waters of Lake Huron. Control measures have slowed range expansion since 1995, but this recent invasion in Lake Michigan indicates that ruffe are continuing to expand in the Great Lakes.
"Although the effects ruffe will have on native Great Lakes fish populations are difficult to predict," said Mark Dryer, project leader for the Services Ashland Wisconsin Fishery Resources Office. "Strong evidence suggests they compete with native fish for food and space." The ruffe is in the same family as native yellow perch, walleye and some darters. In the Duluth harbor where ruffe have become a dominate species, native species like yellow perch and some bait fish have declined. Unfortunately, unlike native perch species, ruffe have no known economic, recreational or environmental value in North America.
Biologists are uncertain about how the fish moved into Lake Michigan. It is possible, though unlikely, that the fish naturally migrated from another location since they were not previously found in Lake Michigan. However, it is more likely the fish was transported in the ballast water of a commercial ship. Ballast water exchange is believed responsible for the initial movement of ruffe from their native habitat in Europe to the Duluth harbor. When a ship takes on ballast water to stabilize a cargo load, aquatic species can be drawn into the tanks and survive until they are released into a new area. Since 1993, the Great Lakes maritime industry has undertaken voluntary measures to prevent ruffe from being spread in the ballast water of Great Lakes ships. However, these voluntary actions may not be 100 percent effective.
The U.S. Fish and Wildlife Service is the lead agency for the Ruffe Control Program that was approved by the Aquatic Nuisance Species Task Force in 1995. The Ruffe Control Program is a joint federal-state-tribal-private partnership that is responsible for monitoring and controlling ruffe populations. Since 1986, Service biologists have been tracking the spread of ruffe by surveying shipping ports, tributaries and coastal locations throughout the Great Lakes. The Ontario Ministry of Natural Resources is also monitoring populations in the Canadian waters of the Great Lakes.
U.S. Fish and Wildlife Service Regional Director Bill Hartwig is less concerned about how the fish arrived in Lake Michigan than what needs to be done now. "It would be helpful to know how these fish got here so we can expand measures to stop future movement," said Hartwig. "But, the more immediate issue is what we do about the ruffe now that they are here. If they move into southern Lake Michigan, it is possible they could enter the Mississippi River ecosystem through the Chicago Canal system."
The Great Lakes and Mississippi River ecosystems were artificially connected when the Chicago Ship and Sanitary Canal was created in the late 1800s. In 2001, an experimental electric barrier was installed in the canal near Romeoville, Ill. Scientists believe an electrical current flowing through the waterway will deter fish from using the canal to move between the Great Lakes and Mississippi River ecosystems. "With round goby, and now Eurasian ruffe, moving from the Great Lakes toward the Mississippi River, it is critical that we ensure this barrier works," added Hartwig. "When you also consider that Asian carp are moving from the Mississippi River toward the Great Lakes at the same time, we have the ingredients for an ecological disaster."
U.S. Fish and Wildlife Service Fisheries Assistant Regional Director Gerry Jackson has recommended an increase in the Services ruffe monitoring and research activities. "We will immediately begin discussing options with our partners to increase monitoring efforts in Lake Michigan to determine the size and range of this new ruffe population. Currently, there are no practical methods available to eliminate ruffe populations in the Great Lakes. Our best approach now is to identify new populations through surveillance so measures to control their spread can be focused. We need to contain existing populations and at the same time increase our research efforts to develop safe and effective methods to control the spread and impact of this and other aquatic nuisance species," added Jackson.
The Service plans to continue working with federal, state, tribal and Canadian agencies, recreational anglers and boaters, the Great Lakes shipping and bait-fish companies, private industries and federal task forces to develop innovative methods to inform people about aquatic nuisance species and what they can do to help control the expansion of these nuisance fish.
The 1990 National Aquatic Nuisance Protection and Control Act (NANPCA), as amended by the National Invasive Species Act of 1996 (NISA), established the Aquatic Nuisance Species (ANS) Task Force to develop a cooperative ANS Program and coordinate all new ANS activities that are conducted, funded, or authorized by the Federal Government. The ANS Task Force is co-chaired by the U.S. Fish and Wildlife Service. The Services ANS Program supports NANPCA and works with others to implement ANS Task Force Program elements so that some exotic species are prevented from invading the United States and, when populations invade, they are monitored and controlled as best possible.
