I bet that the "decent" population of crappie are hammering the YOY LMB and BG during the first 6 months of their lives. I would concentrate on removing a LOT of the crappie and see if that helps the LMB and BG population.
That is what was suggested as I was told the black crappie are not very suspeptable to electro fishing and they were the most common fish type pulled other than golden shiners. The pond has a lot of sticks, limbs and other things in it that make getting around and electro fishing difficult so I'm certain the shallower waters in these areas have more to tell.
