Just a small self serving suggestion.
I think it would be nice if you could fish with rat meat as a valid target for bait. That or make rats drop animal guts more frequently (as they very very rarely do).
As a rat hunting themed PC I believe this would increase my enjoyment of hunting rats immensely.
I'd really dig this too, honestly. I love the fishing sub-system but wish animal guts dropped more or you could use more things as bait!
Added.
Not very effective bait though.