Funny seeing others using that 
Funny thing that, I was just going to PM Bruno about an idea for that, when I noticed it’s already been suggested here. As you can see here, I recently suggested the addition of several new zones (fishing being one of them), as I think if we can get that working, then it would be automatic and zero maintenance. tl;dr of what I speak of:
There will of course be challenges with making it register whether water is in fact nearby and have the hearthlings actually stand by the water’s edge and fish only there and not in a pool of grass, dirt or stone, but I think those are more than solvable.