It takes 10# of forage fish to get 1 LMB to gain 1#. So if 1000 FHM would weigh 5#(ballpark guess) you would have to add 400,000 FHM to get all your LMB to gain a pound.
Find out what GSH are predatory on, and you might be able to sacrifice that for the betterment of something else more needed. HSB like to eat GSH, and if the GSH get big enough before the HSB, then they will be able to spawn successfully and provide a natural food source for awhile.
