I've got some pretty poorly performing fisheries. Can't quite explain why (they're not overlapping and the workers live right next to them), but they only produce about 200food/year for 4 people. I think this is way under what's required so I'm planning to go destroying the underperforming fisheries.
How much food does a person need each year? This way I can know which fisheries are at least subsistence-level and which are not.