Here in Ohio, we haven't had to face too many "alien" species of fish invading yet, but I have heard about, and seen (god I love River Monsters) the Asian Carp Problems in some nearby rivers. The biggest problem we have faced locally, was a lake / river system that had little to no Crappie in it previously, somehow has seen an explosion in their numbers, and drop off in numbers of Bluegill that were of impressive size.
I'm not sure why, but as the Crappie started showing up, the Bluegill size began to diminish. I remember as a teenager catching large numbers of 6"+ Bluegill, a really nice size for eating. (They have lots of small bones, and smaller fish make it harder to get all the bones out). As the Crappie have been introduced, Most are 4-5", and 6" are increasingly rare.
I'm not sure why, but as the Crappie started showing up, the Bluegill size began to diminish. I remember as a teenager catching large numbers of 6"+ Bluegill, a really nice size for eating. (They have lots of small bones, and smaller fish make it harder to get all the bones out). As the Crappie have been introduced, Most are 4-5", and 6" are increasingly rare.
nobody ever slaughtered an entire school with a smart phone and a twitter account – they have, however, toppled governments. - Jim Wright