A couple of additional tools for your pond management toolbox as the population develops might be diligent netting/trapping and consequent removal of BG, and disturbance of their nesting areas during their spawning. What I have in mind there is dragging a rake through the redds or otherwise stirring them up.
My BG population is super low. I've had too many bass until just recently. Sounds like you may just have to spend all day every day fishing. Tough job, I know, but somebody's got to do it.
