Sea lamprey assessment scheduled for Brule River

The continuing battle against sea lampreys in Lake Superior is coming to a popular river in Cook County.  A U.S. Fish and Wildlife Service assessment crew will conduct work on the Brule River near Hovland from Aug. 8-17. The work will strive to estimate the abundance of sea lampreys in and near the Brule. Any information gathered will be used to determine the need for sea lamprey control.

A first step in the control of sea lampreys is to survey streams which are tributaries to the Great Lakes to determine the presence of lamprey larvae. Sea lampreys invaded the Great Lakes during the 1920s and have been a permanent, destructive element of the fishery ever 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 lbs. of fish during its parasitic phase.

Sea lamprey larvae hatch from eggs laid by adult lampreys 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.

WTIP’s Joe Friedrichs spoke with Robert Frank, a supervising fish biologist and larval assessment team leader for the U.S. Fish & Wildlife Services based in Marquette, Mich, about the upcoming study on the Brule.