I'm going to step in this pile in regards to the missing Crappie element in Pat's pond.. At one time, I believed BG were possibly affecting BCP recruitment, but That is an assumption, not any fact. I believe there is another element missing that is needed for both species to recruit to some level.
I've seen crappie recruit in plain, cover free ponds, massive habitat ponds and everything in-between.
I'd love to spend a week down there with my compliment of nets to look at population structure as an experiment. Not sure we could come to a conclusion but there "might" be something show it's ugly face.