Sea lampreys are jawless parasitic fish that attach to host fish and feed on their blood. Their control in the Great Lakes raises significant animal welfare considerations.
Sea lamprey control programmes raise complex welfare questions. The primary control method, the lampricide TFM, kills lampreys (and some non-target species) through respiratory failure. Electric barriers used at spawning grounds cause pain and disorientation to passing fish. Trapping involves prolonged confinement. Meanwhile, fish parasitised by lampreys suffer significant blood loss, open wounds, and often death. Native lamprey populations in their home ranges face different threats including dams blocking spawning migration, causing population decline in species that are not considered invasive.