In 1921, a vampire-like sea lamprey appeared above Niagara Falls; by the late 1930s, it had spread through the Great Lakes and devastated native lake trout

On November 8, 1921, a commercial fisherman pulling nets near Merlin, Ontario, on Lake Erie noticed something unusual attached to one of his lake whitefish: a writhing, eel-like creature with a circular, tooth-lined mouth clamped onto the fish's side. It was a sea lamprey, a parasitic species native to the Atlantic Ocean that did not belong in Lake Erie.

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