When the first alewife, Alosa pseudoharengus, was discovered in Lake Michigan near South Manitou Island on May 5, 1949, few people would have guessed that it would become the best known fish of the lake in less than two decades. Now it competes only with the coho salmon in its claim to such fame. When the third specimen was officially recorded from Milwaukee, Wisconsin, in March 1952, however, a newspaper story carried a somber warning from a knowledgeable yet anonymous official of the Michigan Department of Conservation that the alewife might raise havoc with the native species. This warning was fully justified by fact in the years to follow. An upset of the entire fishery ecology of Lake Michigan was already well under way in 1949 when the sea lamprey was consuming the last vestiges of the lake trout (Salvelinus namaycush) and burbot (Lota lota)- the only abundant and widely distributed predators of the lake. Absence of large predators left the way wide open for a small and prolific species such as the alewife. Under this condition the alewife increased with almost unbelievable swiftness.
