First off, it is in fact likely that if these plants were planted out in the wild or these animals released into a forest they would out-compete other species. But these animals, especially the salmon, are not in a position where they will be released. They live on farms, and as far as I know they can't fly.
Are GMOs safe to eat? Absolutely. Will they ever "escape" and damage the environment? No, and if they did what would be the problem with some better adapted creatures in the wild. Finally, is the fear of GMOs silly? Yes.