If you have ever tried to catch them in a bunch of nets, you would know that they can do just about any maneuver. The average Mississippi channel flow is about 7 mph; they swim that very easily. If the MDWF would ever do a DNA sample on the upper lake waters, they would probably conclude that they are in there. Keep an eye on Pickwick Lake. They are there, just haven't increased in number yet to be a problem. Their DNA has been found in Guntersville.
It's just a matter of time.
BTW, I have a few nets for sale! LOL!