Oh, those unintended consequences, ain’t they a bitch.
Every time. In the Columbia they introduced the northern pike to kill off the lamprey (Lamp Ray) eel which fed on salmon and steelhead eggs and fry. As fate would have it after they decimated the lamprey the new predator turned to...you guessed it, salmon and steelhead eggs and fry. So now they have a $3/fish bounty on the northern pike.