Wanderlust World Wanderlust World The sea lamprey's invasion of the Great Lakes is a textbook case of unintended consequences from human engineering. Before 1829, Niagara Falls formed a absolute barrier—a 50-meter vertical drop that no fish could ascend. The lamprey, a parasitic jawless fish native to the Atlantic, had no access to the upper lakes.
The Welland Canal, opened in 1829 to bypass Niagara Falls for shipping, provided the first artificial pathway. Lampreys gradually migrated through the canal's locks, reaching Lake Erie by the 1830s. Subsequent canal improvements (wider, deeper, more locks) accelerated their spread: Lake Huron (1930s), Lake Michigan (1936), Lake Superior (1946).
In their native range, lampreys co-evolved with hosts; in the Great Lakes, they found naive fish populations—lake trout, whitefish, ciscoes—with no defenses. A single lamprey kills ~18kg of fish. By the 1950s, the lake trout fishery collapsed, devastating a $10M+ annual industry and restructuring the entire food web.
The Great Lakes Fishery Commission (1955) coordinates lampricide treatments (TFM), barriers, and trapping—suppressing populations by ~90%. Yet complete eradication remains elusive; the lamprey's complex life cycle and the system's vastness demand perpetual management—a permanent cost of a 19th-century canal decision.