Just a thought, but if you put some granular high phosphorous fertilizer in one of those bags and sunk it with some brush, that fertilizer would (maybe) stimulate an algae bloom which would bring the zooplankton which would attract the bait fish. I don't know how that would work in a flowing water situation. It might have no effect, but I know in a pond that 10-34-0 liquid will create an algae bloom in just a few days.