Deb, I'm not a Pro or geneticist but I do know that crosses get both desirable and undesirable traits from parents. Downline generations in an uncontrolled breeding "program", like a common pond or a mixed herd of cattle can be watered down or strengthened pretty quickly. Only under lab or controlled conditions can you breed true. If a GG breeds with a green sunfish, its progeny will soon water down on desirable traits.
BTW, you stepped in it when you stated that birds, coons and other varmits stock ponds. That's been cussed and discussed extensively here. Scientifically, you can see that the odds are overwhelming. Eggs don't stick to anything but each other. Check the conditions that fish eggs need to hatch. Odds of survival, even under ideal natural conditions, are pretty lousy for both the egg and the ultimate fry. However, in some ponds, life seems to occur. But it is exceedingly rare. Admittedly, mosquito fish seem to show up.
