Milking cows and goats counted as fish in food production report v0.9.2d

I was taking a closer look at my food production graph and I noticed that my village is somehow producing fish without having built a fishing shack throught my savefile.
After experimenting a bit I noticed that after disabling the cow barn and the goat barn the fish produced amount went down considerably, always in early spring (when they’re supposed to be milked).