YP do overpopulate and cause problems. They will pressure BG yoy and YP yoy. BG over 3 in. will also pressure YP yoy. I would do as Bruce suggested plus put in a few adult SMB . You may well have to many adult YP able to spawn next spring. My guess (but not sure) is that the June 8 in. and Sept. 8-9 in. YP will spawn next spring. Will check on that.