Different strains of smallmouth bass

Look at these two smallmouth bass. They are from the same waters. There is a major difference between the two. Look at the dorsal fin on each. One has the normal rounded fin. The other has much larger fins that come to a sharp point. We refer to the former as Northern Smallies and the later as Spike Smallies. This is not a genetic defect nor is it a difference of the sex of each fish. We've already ruled those two theories out.
My own personal theory is that the Spike Smallies are Neosho strain smallmouth bass. But I can't seem to confirm this theory. I've seen more spike smallies in pictures from southern waters and more round fin northern smallies from Illinois, Wisconsin, Minnesota and Canada.
So..my question to anyone who knows is this: Why are these two fish so different? please give some info and any links to follow leading to a concrete answer. The first one to provide the answer wins a free Customfish.com hat AND a bag of Storm baits.