I totally agree, viking fishing should have been better. I am not sure if harpoon should be able to catch smaller fish but bigger ones should be. Also there should've been other ways to catch fish like nets on ships or baskets. And, there should be a chance% to catch
something weird..
On top of that, needing a cauldron to cut fish is stupid considering we could cook it instantly and survive on long trips before, but now we have to return to kitchen to eat cooked fish...