I think you are a good student, and an even better writer.
You've pretty much got it nailed.
Your imbalanced fishery can be managed with most impact by harvest, and feeding. This is how you can add wealth in the form of additional calories, and redistribute that wealth, by limiting the number of mouths fighting for the calories.
The best way to determine which fish need to be harvested is to report on the size distribution of fish, relative weights of the various sizes, and the types of fish present. This can be done through angling, or more specifically through netting or electrofishing.
