An assessment crew from the U.S. Fish and Wildlife Service will be surveying the Nemadji and St. Louis rivers from June 11-20 to estimate the abundance of sea lampreys. Information gathered will be used to determine the need for sea lamprey control.

Sea lampreys invaded the Great Lakes during the 1920s and have been a permanent, destructive element of the fishery every since. Sea lampreys attach to fish with a suction cup mouth, rasp a hole though the fish’s scales and skin, and feed on blood and body fluids. The average sea lamprey will destroy up to 40 pounds of fish during its parasitic phase.

Sea lamprey larvae hatch from eggs laid by adults in gravel nests and drift into silty bottom areas, where they burrow and live for several years. Also, larvae sometimes drift out of streams and settle in the immediate offshore areas near stream mouths. Failure to detect and subsequently eliminate larvae allows the lampreys to transform into parasitic adults and kill Great Lakes fish.

Fishery biologists and technicians conduct surveys for sea lamprey larvae in hundreds of Great Lakes streams each year. Most surveys are conducted by electrofishing, but in deep waters crews use a granular sea lamprey larvicide approved by the United States Environmental Protection Agency. It is sprayed over the surface of the water and sinks to the bottom, where it dissolves and causes laval lamprey to leave their burrows and swim to the surface for collection.

Call 1-800-472-9212 for more information. TTY users may reach the Marquette or Ludington Biological Stations through the Michigan State Relay Service at 1-800-649-3777.