Targeted lampricide treatment strategies for sea lamprey suppression in the Great Lakes: 2008–2018

Abstract

The invasive sea lamprey, Petromyzon marinus, continues to be a persistent threat to the Great Lakes fishery. Beginning in 2008, the Great Lakes Fishery Commission’s resources for controlling sea lamprey were increased and directed toward maintaining sea lamprey populations at or below target levels utilizing experimental lampricide treatment strategies. The Commission’s Sea Lamprey Control Program executed five targeted treatment strategies in the Great Lakes from 2008 to 2018. These strategies focused on killing large numbers of sea lamprey larvae prior to metamorphosis. Strategies included consecutive lampricide stream treatments (streams treated twice within three years), comprehensive treatment of specific geographic regions, and increased treatment effort toward the most productive sea lamprey streams. Determining the effect of individual strategies proved challenging and results were mixed; yet, the additional treatment effort expended in the upper Great Lakes appears to have contributed to overall declines in the index of adult sea lamprey abundance. The complete effect this additional treatment effort has on sea lamprey populations may be revealed through future assessments.