Recent Investigations on the Sea Lamprey, Petromyzon Marinus, in Ontario

Little Thessalon River is an important spawning ground for the sea lamprey, as compared with Desbarats, MacBess, Livingstone, and Lauzon Creeks. More research is necessary to determine the reasons for this difference. The selection of areas by the sea lamprey for spawning confirms the observation of Coventry (1922). Furthermore, the sea lampreys entered the weirs at night, the majority 1 or 2 hours past midnight. Sea lampreys were taken during the earlier period of the sucker run. The majority of the sea lampreys averaged 24 inches in total length. Seventy-five percent of the suckers were scarred, presumably by lampreys. As the numbers of sea lampreys increased the numbers of suckers decreased. Hoop nets are not effective for trapping sea lampreys. Metal weirs are essential, and the wings should be 5 feet deep, measured vertically from the bed of the stream, in order to avoid an overflow during periods of heavy rainfall. To avoid the escape of lampreys the floor of the trap must be screened, and ...