Int'l Effort Eliminates Nearly Half of Sea Lampreys in St. Marys River

For Immediate Release Contact: Marc Gaden

December 2, 1999 734-662-3209 x. 14

International Effort Eliminates Nearly Half of the

Sea lampreys in the St. Marys River

Future Much Brighter for Lake Huron Fish

Ann Arbor, MI—After an extraordinary international effort, the Great Lakes Fishery Commission today announced that preliminary assessments show significant reductions in sea lamprey larvae populations in the St. Marys River. The reductions are the result of a large-scale Canadian and U.S. control efforts there this past summer. The announcement came following reports from Fisheries and Oceans Canada, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey, who assessed and carried out the St. Marys River sea lamprey control this past July. Their data indicate that the lampricide treatment eliminated nearly half of the sea lampreys in the St. Marys River. They also achieved a significant increase in trapping and sterile-male-release. The integrated lampricide, trapping, and sterile-male-release puts the Commission on-track to eliminate 92% of the sea lampreys produced in the river, thereby achieving the goal of reducing parasitic lampreys in Lake Huron and northern Lake Michigan by 85% over the next 15 years.

Sea lampreys invaded the Great Lakes in the early part of the 20th Century through shipping canals. Their impact on the valuable fishery was immediate and devastating: fish harvest declined dramatically and the thriving fish communities, based on native, self-sustaining fish stocks, were thrown seriously off balance. In 1955, the governments of Canada and the United States created the Great Lakes Fishery Commission to control sea lampreys. Since then, the Commission has suppressed sea lamprey populations in most areas by 90%, paving the way for successful stocking, rehabilitation of native fisheries, and the resurgence of sport and commercial fishing.

Despite this success, the St. Marys River remained a major trouble spot in the Great Lakes, producing more sea lampreys than all of the other Great Lakes combined. These lampreys migrated downstream and feed on large numbers of fish in Lake Huron and northern Lake Michigan. Control on the St. Marys River had been elusive because of the river’s size, tremendous flow volume, and a lack of funds to do the job.

In 1997, after careful planning and a $3 million contribution from the State of Michigan, the Commission started control on the river with a multi-faceted attack on the sea lampreys inhabiting the river. They began with an all-out effort to suppress successful spawning by stepping up trapping efforts, removing females, and annually releasing tens of thousands of sterilized male sea lampreys. In 1998 and 1999, the commission added the most ambitious element of the plan, application of a granular, bottom-release formulation of the lampricide Bayluscide. Those applications were directed only at areas of high lamprey density, selected after sampling more than 12,000 sites across the river during 1993-1996.

"Preliminary assessment data show the 1999 treatment was a tremendous success, meeting or exceeding expectations in all significant areas," said Commissioner Roy Stein of Ohio State University. "In the plots treated with lampricide—which amount to a very small percentage of the river’s surface area—an estimated 88% of the sea lamprey larvae were removed. Previous field estimates predicted 75% removal. On a whole-river level, the lampricide spot treatments have eliminated 45% of the sea lamprey larvae, close to the 50% removal rate originally predicted."

Stein continued: "We also have had great success with trapping and the sterile-male-release initiative. With the fully functioning new trap at the U.S. Corps of Engineers facility in Sault Ste. Marie, Michigan, and with further refinements to the Great Lakes Power trap in Sault Ste. Marie, Ontario, we increased overall trap effectiveness from 40% during 1998 to 56% in 1999. That means 56% of the estimated 20,000 spawning sea lampreys in the St. Marys River were removed through traps alone."

"With the increased harvest of sea lampreys in the St. Marys, along with lampreys trapped in other locations, agents were able to release 26,000 sterilized male sea lampreys in the river, achieving a ratio of 4.7 sterilized males for every fertile male," said Commission Chairman Burton Ayles. "This is a large increase from the 2.2 to 1 ratio achieved during 1997. This is also much greater than the ratio of 3 to 1 used in our forecast. Together, the integrated trapping and sterile-male-release efforts are estimated to have reduced the reproductive potential of the St. Marys River by a remarkable 92%."

"We are greatly encouraged by the results of the St. Marys River treatment," Ayles continued. "The men and women who carried out the treatment should be congratulated for their efficiency and effectiveness. The benefits to the Lake Huron and northern Lake Michigan fish communities, and to the millions of people who fish the Great Lakes, should be felt within the next few years. Assessment is critical now; we need to keep close tabs on our progress. The Commission will remain vigilant and will continue to aggressively control the St. Marys River sea lamprey populations until our 85% reduction goal is reached."

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