[AndyS]

You like so many others have a lot to learn. There are INTRODUCED fish and there are INVASIVE fish. The fish stocked over the years by our hatcheries are INTODUCED, yes Brown Trout can be listed as INVASIVE when they compete with native Brook Trout. The majority of our stocked fish don 't even spawn.
Snakeheads are INVASIVE and spawn twice a year.
INVASIVE fish DIPLACE the other fish by eating all their food.
I just wish all you closet arm chair biologists would get this through you thick skulls. The Blue Catfish are going to decimate entire coastlines, just sit back, and watch, this is only the beginning.