Sterilized male sea lampreys are released into the St. Marys River, in Sault Ste. Marie, Michigan. - FWS photo

Crews from the Marquette Biological Station sterilized about 20,000 male lampreys in May for release into the St. Marys River. 

Spawning phase lampreys were collected from traps at 22 streams on four of the Great Lakes in the U.S. and Canada for use in the technique. 

Sterilization operations will continue through July, though the bulk of activity occurs in May. 

The sterile-male-release technique reduces reproduction by causing females to waste their eggs in matings that will fail. 

Trapping and sterile-male releases have reduced reproduction in the river by about ninety percent since 1997. 

The Service delivers an integrated program of sea lamprey management in the Great Lakes as a contracted agent of the Great Lakes Fishery Commission.