I am trying to create an island with a large settlement on it, the people of this settlement need to be able to sustain themselves and according to Medieval demographics made easy (MDME)
A square mile of cultivated land (including not only farmland, orchards and pastures, but also the roads and settlements attendant to them) will support around 180 people. This takes into account normal blights, rats, drought, and theft, all of which are common in most worlds.
However, the MDME estimate does not seem to account for fishing. Given that the settlement is surrounded by the sea and therefore will make heavy use of fishing as a way to feed it's population.
How would the land area required to sustain the population change? If fishing can be a substitute for the pastures needed to provide meat to meet human dietary requirements.
Assuming: There is plenty of space to fish and plenty of fish to catch