Transplantation of prespawn adult Sea Lampreys as an important restoration strategy.

This article focuses on the restoration of anadromous Sea Lamprey (Petromyzon marinus) populations along the Atlantic coast of the USA, where numbers have declined due to barrier dams. The study demonstrates that simply providing fish passage at dams does not restore runs in streams lacking resident larval lampreys, as adult Sea Lampreys are attracted to pheromones produced by larvae. Experimental transplantation of prespawn adults into such vacant upstream habitats successfully re-established spawning runs and larval populations, which then attracted subsequent adult migrants. The findings suggest that transplantation of prespawn adults is a practical, low-cost management tool to restore Sea Lamprey runs in rivers without remnant populations, complementing fish passage improvements. This approach acknowledges the species’ non-natal homing behavior and panmictic population structure, indicating that restoration outcomes may vary and require strategic, watershed-specific efforts.