I don't believe that "they just moved up from deeper water" story. That lake was muddy. I've caught bass out of farm ponds that didn't have 2" of visibility that you would swear were albino they were so white and I've also caught fish in 40 foot that were the prettiest coloration. I believe and like others have said I'm no biologist, but my believe is that the water color and cover they live in dictates their pigments.
This sounds more likely to me.
+1.......... Supposedly, the water clarity was about 3 inches. So, yea, they were light colored. As far as "moved up", no. Moved over is more like it. Wheeler had spent most of his practice time mapping, not fishing. What he found was bass suspended OVER deeper water adjacent TO flats, humps, etc, in about 6-8' . He ran from spot to spot that he had previously mapped until he found the ones that had moved over to the flats in about 6-8 ft of water that was adjacent to the deeper water. He found that when they moved over out of the deeper water, they were feeding.