Downs, W., 1982. Sea Lamprey: Invader of the Great Lakes,  University of Wisconsin Sea Grant Institute

A fact sheet produced by the University of Wisconsin Sea Grant Institute

Sea Lamprey: Invader of the Great Lakes

With a final glance at his watch, a U.S. Fish and Wildlife Service (FWS) technician flips the switches. A perforated pipe squirts a yellow liquid into the stream. In a widening patch, it slides over the stream bed and around the bend.

On other streams feeding the same river, similar patches of chemically treated water drift away, precisely timed to meet -- if all goes as planned -- as the streams join in their rush to Lake Michigan.

About an hour later, small worm-like fish wriggle out of the stream bed and rise to the surface, writhing in the throes of death. These are sea lamprey ammocetes -- "sand-burrowing" larvae of a destructive parasitic fish that is all too common in the Great Lakes. Had it lived, each ammocete would have grown into a 12 to 20-inch adult sea lamprey and in its short career killed some 40 pounds of trout, salmon, whitefish and other Great Lakes fish.

U.S. and Canadian agencies spend weeks preparing to treat Great Lakes tributaries with the chemical lampricide. Lamprey control crews survey drainage basins and calculate stream flows and volumes. On streams treated for the first time, the crews must find good spots to Introduce the lampricide and roads or trails to reach those often remote places. Biologists must test each stream and determine the exact chemical concentration that will kill the sea lamprey larvae and yet do little harm to other aquatic life. During treatment, samples must be taken at various locations downstream to make sure the lampricide hasn't become too diluted to be effective.

It is a painstaking task, but one that has become crucial to the survival of the Great Lakes fisheries.

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Keywords: Basic_biology, Outreach, Sea_lamprey
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