How were sea lamprey populations controlled in the Great Lakes?

To control invasive sea lamprey populations in the Great Lakes, governmental agencies in the United States and Canada have implemented a multi-faceted management strategy. These efforts have successfully reduced lamprey populations by approximately 90 percent by the 2020s.1

Control methods include:

• Targeting Larvae: Wildlife officials apply lampricides to streams adjacent to the lakes. These chemicals are specifically designed to eliminate lamprey larvae in their burrows while sparing other aquatic species.1
• Preventing Migration: To stop adult lampreys from reaching spawning grounds, officials deploy various physical and technological barriers, including traps, nets, and electrical barriers.1
• Attractants: Researchers utilize attractant chemicals to lure lampreys into traps or away from spawning areas.1

These interventions are essential for protecting native fish populations, such as lake trout, which suffered significant declines following the lamprey's expansion into the upper Great Lakes via the Welland Canal.12