Like salmon, [lamprey are] anadromous, growing up in freshwater before migrating out to sea. They return to spawn but lack site fidelity, meaning they don’t return to their home spawning grounds. An adult lamprey in the Columbia River could have hatched upstream in Russia or Japan. … [O]n the eponymous Eel River in Northern California, a former agency fish biologist named Damon Goodman helped build a monitoring station in 2016 to count returning lamprey. The station doubles as a fish passage uniquely designed for lamprey to circumvent the Cape Horn Dam.