For Immediate Release
July 26, 1996

Contact: Marc Gaden
313-662-3209 ext. 14

Great Lakes Fishery Commission, Management Agencies to Conduct Essential Dye Study in Preparation for Future St. Marys River Sea Lamprey Control

Effective Control Pivotal to the Strength of Lake Huron and Lake Michigan Fisheries

Fishery management officials from federal, state, provincial, and tribal agencies will conduct an essential study August 10-11 to determine the effectiveness of a large-scale lampricide treatment to control sea lampreys in the St. Marys River. The study--designed to simulate the transport of the commonly used lampricide TFM--will track the movement of a dye applied to the river and will help determine whether lampricides would reach lamprey hotbeds at effective concentration levels. Officials hail the study as a major step toward gaining the upper hand on lampreys in the St. Mary River. The St. Marys River is the largest undercontrolled source of sea lampreys in the Great Lakes due to its tremendous volume and excellent sea lamprey spawning habitat. Because of sea lampreys from the St. Marys River, the Lake Huron and northern Lake Michigan fisheries are seriously threatened.

The planned dye study is part of a comprehensive information-gathering project to develop an effective sea lamprey control program for this large interconnecting channel. Since 1992, the Great Lakes Fishery Commission has supported extensive assessment efforts to locate and map the distributions of lamprey larvae in the river. A previously developed computer flow and transport model has suggested that a lampricide treatment would be effective in the north channel portion of the St. Marys River but may not be effective in the Lake Nicolet portion (see figure). The planned dye study is required to verify and calibrate the flow and transport model results.

Agents plan to slowly apply the dye from the railway bridge upstream of Great Lakes Power (GLP) for about 14 hours beginning at 6:00 a.m. on August 10. The dye will be visible for a short distance below the railway bridge. Once mixed by the GLP hydroelectric turbines, the dye will be invisible to the naked eye.

As the dye moves down the St. Marys River, its fluorescence (and thus its concentration) will be measured by reading water samples with a fluorometer. Crews will take samples from numerous locations (transects) from below the GLP plant through the north channel to Lake George and through the south channel into Lake Nicolet. The data will be summarized and compared to known locations of sea lamprey larvae. Transect sites will be marked with visible objects such as buoys and shore based markers. Sampling will begin immediately after initiation of dye application and will continue for about 48 hours until the dye block dissipates below Lake George and Lake Nicolet. The rhodamine WT dye is harmless to human and aquatic health at the concentrations at which it will be used during this study.

Water quality and habitat improvements during the past decade have turned the upper St. Marys River into one of the best sea lamprey spawning grounds on the Great Lakes. The river is now the largest undercontrolled source of lampreys in the Great Lakes, harboring millions of lamprey larvae and producing over 500,000 parasitic-phase lampreys annually--more than all of the other Great Lakes combined. Conventional treatment of the river's tremendous volume has not been attempted because of unresolved questions of effectiveness and cost.

Annual damage to important sport and commercial fish species in northern Lake Huron and Lake Michigan is estimated in the millions of dollars. The problem is so serious that fish stocking has been halted in some areas and fishery managers from Ontario, Michigan, and the Chippewa-Ottawa Fishery Treaty Management Authority have identified sea lampreys from the St. Marys River as a critical impediment to reaching fish community objectives and to achieving lake trout restoration in Lake Huron.

"State, provincial, and tribal fishery management officials will be largely unsuccessful in meeting fish community objectives in Lakes Huron and Michigan as long as lampreys have the upper hand in the St. Marys River," commented Ron DesJardine of the Ontario Ministry of Natural Resources, and Vice-Chair of the Lake Huron Committee. "I commend all those who are cooperating in this dye study for their continued dedication to solving this serious lamprey problem."

Larry Schleen, lamprey control supervisor with the Department of Fisheries and Oceans, added: "The forthcoming dye study is a vital step in our plans to tackle the St. Marys River problem. The data we gather from this study will allow management officials to plan and implement a cost-effective lamprey control program in the St. Marys River."

The Canadian Department of Fisheries and Oceans, the U.S. Fish and Wildlife Service, the Chippewa-Ottawa Treaty Fishery Management Authority, the National Biological Service, the U.S. Army Corps of Engineers, the State of Michigan, the Province of Ontario, and the Great Lakes Fishery Commission will contribute resources and manpower to conduct the study.

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