They are overfished largely in order to be fed to other animals. Similarly we clear too much land to farm corn but we do it because it gets fed to animals. But

They are overfished largely in order to be fed to other animals. Similarly we clear too much land to farm corn but we do it because it gets fed to animals. But nobody would refer to this to argue against eating corn. I don't know how to quantify the potential sustainable yield of forage fish vs. the human diet, but I know that eating small fish is more sustainable than feeding them to larger fish and eating those.