How can I avoid fish/deer extinction?

Solution 1:

I have personally come to the conclusion that overlapping is bad, anything else is fine and dandy. As a test I had ten fishing huts along a river, but none of them overlapped, and they all produced (roughly) the same amount of food, showing no decline as the river went on.

As soon as I overlapped them however, it seemed to decrease the production instantly. As such, your best bet is to simply spread everything out to make certain they do not overlap.

Also, make sure you do not chop down the forests around your hunting lodges, as the forest is important for its productionrate.

Solution 2:

Theik is correct, but I just wanted to add to clarify: Fish/Deer will not go extinct, even if hunting lodges or fishing huts overlap. As soon as you destroy the overlapping building, the first building's production should go back to what it was before the overlap. Fish and Deer production are constant and based entirely on other factors (which seems to be amount of favorable land, water tiles for fishing for example).

From the "Myths" section of the FAQ on the Banished Wiki:

"You need to worry about overhunting/fish stocks depleting over time/soil degradation from farming" - these features apparently never made it into the final game. However, overlapping hunting cabins/fishing docks will reduce average catch per citizen.

Source: http://banished-wiki.com/wiki/Tips