Which management tool is commonly used to control Sea Lamprey populations in the Great Lakes?

• A. Introducing natural predators for the lamprey
• B. Lampricides
• C. Physical barriers
• D. Nutrient enrichment to favor other species

Answer: (B)

Controlling an invasive aquatic pest by targeting its larval stage with a selective chemical in its native habitat. Sea lampreys spend years as larvae living in tributaries, so applying lampricides in those streams kills the lamprey larvae before they migrate to the Great Lakes as adults. This directly reduces the number of lampreys that can reach the lake and become parasites on native fish, helping fish populations rebound. The lampricides used (for example, compounds like TFM and certain formulations of niclosamide) are applied at carefully timed concentrations to minimize harm to non-target species, making them an effective, targeted tool in the overall management program.

Other approaches—trying to introduce predators, relying on physical barriers to block migration across many streams, or attempting to change nutrient levels to favor other species—are less practical or would cause ecological problems and are not as effective at reducing lamprey numbers on a large scale. Lampricides remain the most widely used method for reducing Sea Lamprey populations in the Great Lakes.