James,
George has been restocking with 50 fish every year in a 2+ acre pond with and seems satisfied. Restocking density probably depends more on how much you fish in the summer and whether you lose those fish caught during the summer. Also base your restocking density on the numbers removed. Restocking 10-15 fish per acre per year seems like it makes most sense for most people.
If your HSBs aren't eating pellets during the winter then don't worry about that, just make sure that they get groceries when the water temp is right...60-80 degree water represents good growing conditions.
Hope this helps you.
