Sounds like you stocked too many LMB to begin with with little forage base to start off. The LMB hit their biomass max as 6"-10" fish. Unless you removed large numbers of them and soon, they'll spawn and makes things even worse... I would keep every single LMB you catch and next spring I would stock as many and as big a BG as you can source. 5"+ BG would be best... Adding large numbers of LARGE GSH could also help. Canal cats? Would these be brownish as in bullheads or silvery blue as in channel cats?