With any species/fish there is an energetic point of no return. If the energy required to maintain basic body functions can't be sustained above what energy is expended to obtain food, then that fish is history before long.
I would not want to be a LMB trying to survive on nothing but gams and/or FH.
Thanks ewest for the important caveat.
This thread has gotten a little long, but I was referring to options to load the pond with forage in the pre-predator, early-predator stages.