I've always been interested in why the size differences between the average panfish in southern waters as opposed to those hugging the Canadian border for instance. I know they'd have a longer season down south where their metabolism is in higher gear due to warmer water on average. But does that alone account for the larger fish? Last I read, the subspecies of Largemouth Bass from Florida was just inclined to grow bigger than a strain from say, New England. Put them both in the same water from minnowhood, and the Florida Bass is going to top out larger in adulthood simply from genetic differences.

I also know that in northern ponds, sunfish (and perch, crappie, bass, etc.) often stunt from overcrowding if there are too many fish/not enough predators, but that shouldn't be any different with southern waters. I've fished ponds at both extremes of north and south, and I didn't see any obvious differences in the amount of food in the water. Any biologists out there, amateur or pro who has a handle on it?