I am no expert, but one interesting observation is that if your YP are not reproducing and your FHM are all gone, I would suspect that now your SMB are "the forage base" for the YP. The YP are probably eating all the SMB young and this would also explain why you don't see much SMB recruitment (besides the SMB eating their own young as well). I think BG would give some forage, but as mentioned by most, SMB are not enough to control them stunting (versus LMB). If you have a bunch of weedbeds, I would try some Gambusia (mosquito fish) for forage as well for the YP.
