Sea lamprey, Petromyzon marinus

The adult stage of the sea lamprey is parasitic on other fishes, attaching to them with its oral disc, rasping a hole, and sucking out blood and body fluids. Lamprey parasitism can reduce populations of some host fishes. The sea lamprey gained access to the upper Great Lakes following opening of the Welland Canal, gaining passage around Niagara Falls. Sea lamprey parasitism reduced populations of lake trout and other valued species. Weirs were constructed to control access to spawning streams, and TFM, a selective lampricide, has been applied in the effort to control the sea lamprey.