1. Chemical Control: The most widely used method is chemical treatment of streams and rivers where lampreys spawn. A chemical called TFM (3-trifluoromethyl-4-nitrophenol) is applied to designated waterways during the lamprey larval stage, effectively killing them without significant harm to other aquatic organisms.
2. Barriers: Constructing physical barriers, such as dams or electric barriers, can block lampreys from reaching their spawning grounds. These barriers prevent adult lampreys from migrating upstream and reproducing.
3. Sterile-Male Technique: This method involves releasing sterile male lampreys into the wild, which compete with wild males for females. Since the released males are sterile, their mating attempts result in unfertilized eggs and reduced reproduction.
4. Trapping: Traps are set in streams to catch adult lampreys during their spawning migration. These traps can be baited or equipped with attractants to lure the lampreys and remove them from the ecosystem.
5. Habitat Modification: Altering lamprey habitats can make them less suitable for spawning. For example, installing streambed barriers or modifying water flow patterns can disrupt lamprey spawning and reduce their numbers.
6. Integrated Pest Management: A comprehensive approach combining several control methods can be effective in managing sea lamprey populations. By using a combination of chemical treatments, barriers, trapping, and habitat modification, fishery managers can minimize the impact of lampreys on Great Lakes ecosystems.
7. Natural Predators: Introducing natural predators of sea lampreys, such as lake trout or Pacific lamprey, can help reduce their population. These predators prey on lampreys during different stages of their life cycle.