For Immediate Release

April 21, 1997

Contact: Marc Gaden

313-662-3209 ext. 14




ANN ARBOR, MI — Fishery managers from Michigan, Indiana, Illinois, Wisconsin, and the Chippewa-Ottawa Treaty Fishery Management Authority met recently in Ann Arbor, Michigan and expressed concern over increases in sea lamprey and declines in yellow perch in Lake Michigan. The sea lamprey, a fish native to the Atlantic ocean, invaded the Great Lakes in the early part of this century and wreaked havoc on the fishery, driving many commercial and sport fish stocks to the brink of extinction. Sea lampreys, though once under control, are again causing significant damage to the Lake Michigan and Lake Huron fisheries due to high levels of lamprey production in the St. Marys River. During the meeting, the Lake Michigan Committee supported a proposal to begin sea lamprey treatments in the St. Marys River. The committee also noted that severe reductions in yellow perch abundance show no sign of improvement after several years of decline in the western and southern portions of Lake Michigan and after minimal recruitment in Michigan waters.


Lake Michigan fishery managers reported that sea lamprey wounding rates in Lake Michigan are at a significantly high level. Said committee member Tom Trudeau of the Illinois Department of Natural Resources: "Lake Michigan’s sea lamprey problems have worsened considerably over the past ten years. Not only are wounding rates significant in the northern part of Lake Michigan, but wounding rates appear to be increasing in the southern part of the lake as well. In the Julians Reef area in Illinois waters, for instance, we may be seeing an increasing trend in sea lamprey wounding rates." Sea lamprey wounding rates in Lake Michigan—particularly in the northern part of the lake and in open-lake lake trout spawning sites—are approaching the wounding rates seen before lamprey control began in the 1950s, prior to the collapse of the fishery.

The cause of the increase in Lake Michigan lampreys is primarily due to lamprey migration from the St. Marys River, the connecting channel between lakes Superior and Huron. A joint U.S.-Canadian sea lamprey control program has reduced sea lamprey abundance by 90% in most areas of the Great Lakes and has allowed fishery agencies to stock fish and implement fishery restoration measures. The St. Marys River is the lone exception to this remarkable sea lamprey suppression record. The river produces more lampreys than all of the other Great Lakes combined; sea lamprey control in the St. Marys River has been impossible traditionally because of its large size and tremendous flow volume.

During its meeting, the Lake Michigan Committee agreed with the Lake Huron Committee that sea lamprey control in the St. Marys River is a top priority. To combat the problem, the Lake Michigan Committee concurred with a proposal to combine the granular Bayer lampricide with trapping and the Sterile-Male-Release-Technique to achieve an 85% reduction in Lake Michigan and Lake Huron sea lampreys. This proposal was developed by sea lamprey control biologists and research scientists working under the direction of the Great Lakes Fishery Commission.

"The continued trend of high sea lamprey wounding rates in Lake Michigan is intolerable," said Lake Michigan Committee Chairman John Trimberger of the Michigan Department of Natural Resources. "The high wounding rates we are experiencing are contrary to fish community objectives and indicate that we must address this problem if our efforts to restore and maintain native species are to be successful and if we want our native and introduced sport stocking programs to be meaningful. Reducing the flow of sea lampreys from the St. Marys River will be a major factor in reducing sea lamprey predation in Lake Michigan."


The Lake Michigan Technical Committee reported that yellow perch abundance in Lake Michigan continues to decline precipitously in Wisconsin, Illinois, and Indiana waters while showing only minimal recruitment in Michigan waters. Significant numbers of yellow perch larvae are not surviving well to the young-of-the-year stage, which means that aging adult populations are not being replaced readily by new generations of perch in Lake Michigan.

Scientists are not sure of the cause of the yellow perch decline, though they do agree that the fish are not surviving to a harvestable age. To study the situation further, the Yellow Perch Task Group, established by the Lake Michigan Fish Chiefs, will narrow its focus to two areas: alewife predation on larval perch and early perch fry mortalities. The task group recommended that a lakewide tagging study be conducted to investigate yellow perch movement and homing to spawning sites.

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