The sea lamprey is an invasive fish with a round mouth like a suction cup. It latches onto big fish like lake trout and salmon, drills its razor sharp tongue into them, and gets fat drinking their blood and body fluids. A single lamprey can kill up to 40 pounds of fish in its lifetime.
We spend about $20 million dollars a year to control lampreys. One of the main ways people do that is with a pesticide, but researchers are working on other ways to control the invasive species.