I don't think anything can really out spawn bluegill. However, in a bass heavy pond, nothing gets a chance to mature enough to feed larger bass.
I don't know of anyone who has tried adding crappie to a bass heavy pond but it might just work. I figure you would have to stock larger ones to avoid immediate predation.
My 0.7 acre pond is very bass heavy, and it had crappie in it when we bought the place. The bass seem to keep them in check. We've gone entire seasons without catching any crappie. Actually, I haven't caught one in at least the last 14 months. When we do catch crappie, they are usually 12-14 inches, but very skinny. I'd prefer that they were not in my pond, but . . .
