Absent feeding pellets and or increasing the plankton community BG will likely stunt. You need to remove small BG in order for the larger ones to have enough food. Seining will help. A few (all one sex)LMB will help. IMO with out feeding/fertilization and some help removing small BG you will have a hard time keeping the BG population in check. Fishing usually removes the fish you would rather keep in the pond. In other words harvest by fishing alone is not the best way to have a pond with lots of large BG. Its the 2 , 3 , 4 inch BG that need to be reduced.