The problem of controlling the sea lamprey in the upper Great Lakes has received considerable attention in recent years and requires no review here (Applegate and Moffett. 1955). Electromechanical weirs and traps and electrical barriers have been developed which can be successfully employed to block and/or destroy spawning runs of adult sea lampreys. These devices. when installed in all known $pawning streams. provide an effective method of reducing the numbers of sea lampreys in each lake basin. Initial efforts at control of the lamprey have employed these devices (Applegate. Smith. and Nielsen. 1952; Erkkila. Smith. and McLain. 1956).