How big are the LMB now ? If you stocked 2-3in LMB one year ago they have not eaten all the FH YP and craws yet. Before you add more you need to know what is there and how they are progressing. There are several ways of assessing what's there including fishing , traps , seine , visual and electro shock boat. You don't need the last one yet. Gather some more info and tell us what it is.

BTW the advice to stock yoy predators along with the forage is not unusual for northern ponds and may well work.