Exotic animals and plants are crisscrossing the globe as never before. Many of these unwelcome species have found their way to the Chicago area and are wreaking havoc on our local ecosystem.

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NAME: Sea lamprey (Petromyzon marinus)
ORIGIN: Atlantic Ocean
DATE INTRODUCED: 1835 (Lake Ontario); 1921 (Lake Erie)
HOW IT GOT HERE: Arrived in Great Lakes through Welland Canal

With its suction-cup mouth filled with sharp, hooked teeth, this parasitic, snakelike invader attaches itself to a host fish, chews a small hole, and feeds off the victim’s blood, either killing the host or severely weakening it. Lampreys are believed to be responsible for the declining lake trout and salmon populations, particularly in the Great Lakes. By wiping out large numbers of lake trout, which are indigenous predators, sea lampreys have allowed other invasive prey species, such as rainbow smelt and alewives, to flourish without any competition. Deterioration in the stock of large fish has also hurt commercial and sport fishing across the Great Lakes.

THE FIGHT: Sea lampreys are one of the few aquatic invasives that have been kept in check. Scientists use a chemical toxin specific to lampreys (a mixture of trifluoromethyl and nitrophenol, or TFM) in infested waters and in potential breeding areas. They are also experimenting with pheromones to disrupt lamprey migrations and mating.