If the LMB (or some of them) turn out to be pure FL strain, I'm still not sure what that tells you. There are many places that sell pure FL strain bass, or claim to sell pure FL strain bass, so a FL bass can occur anywhere, truly.
Don't get me wrong though, I'm not saying you should not do some DNA testing. I'm just not sure the effort will clear up what happened.
I do see what you are saying about keeping some of the bass if they turn out to be some kind of desirable strain.
Well if they are pure Florida, then I would think that the likelihood that they were bucket stocked would be much slimmer, since, I would think, anything coming from a lake would not be PURE Florida.
But the main thing that it would tell me is that I would not need to be concerned about removing all of the fish via rotenone. I could just work with what I have instead of starting over.
