Yeah and we also know that those 1000 are dieing off. They reproduced just because of the massive amount that was thrown out there but are slowly being weeded out due to the climate and predators.
I also would argue that these snakes are actually helping the ecosystem more then hurting it, i have no scientific evidence to validate this but i do have logic. These snakes eat once every 3 months when the meal is large enough, they are breeding and releasing 50-80 eggs which are all about 12 inches when born and have no idea how to survive in a swamp ecosystem. Those hatchlings are being eaten by everything, yes they are eating as well but as we all know their metabolism is incredibly slow. One or two out of that 80 are surviving to be a 10ft snake, which can still be killed by a alligator.