I know that I had a few that had gotten really old and started going down hill. Sometimes even though you think you have plenty of forage there may not be anything for certain size bass to eat. You may have plenty to feed the smaller bass and larger bass but nothing that the 14-18" bass are feeding on. In other words you may have to many bass in that 14-18" size range and they have over eaten the size bluegill and shad that they were feeding on and it takes 3 times as many of the smaller ones to keep them up, and they may be wasting too much energy trying to catch those smaller forage fish so not much is actually going to gaining weight. I just reread jakes post and thats pretty much the same thing he said.