Before leaving south, go to a commercial fishing
supply and look around. Boxes of hooks, different sizes for different fish
. Spools of line for handlines. Sharpening stones and fillet knives. Gloves, different sizes. Bandage kits. Lifeguard hats. Sunglasses. Waterproof storage
bags and boxes. Plastic buckets with lids. Stuff for the fisherman's wife and kids
when he comes home for the day: soccer balls (and air pumps), shampoo and conditioner, jars and cans of seasonings, hand lotion, first aid kits (with tweezers!), and anything you particularly like having plenty of while out there in the sun and sea for long periods of time. It's a long way from a fish camp to a fully stocked market or farmacia. If the fisherman can't particularly use something, someone he knows will be happy to be the recipient of his generosity.
And if you really want to score points, DON'T TRADE
. Just make a straight across gift and see what happens. Your return on investment will exceed your expectations.