What about the ability to catch fish and sharks and take them back to the merchant for sale...
Sharks & Fish can be taken dead or alive, but more for alive. You can either haul it up on your ship and it hangs there from the mast for all to see, or you can hall around a giant cage from the back of your boat you have to lure the sharks into with either bait or yourself. These cages cause be snapped by a pirate sword or from a strong storm.
Have several different types of sharks also, different rarities like the other animals. Just seems silly that if you make your game 80% out of water, you should have more things to do in that water. Let people fish from their boat, give something to do while sailing around.
