Id like an advanced fishing guide, not only where to find what but also where to sell what fish and what fish to make fishmeat out of aswell as good ships/perk setups for fishing and how to avoid getting ganked while fishing and so on =)
edit, i made a little experience with droprate of sealed bottles.
i went out from gustavia, sailed east past codrington to the border of the map. at the east map border i turned north and sailed as far north as north goes, rounded sommerset and went west following the northern border of the map until i could see the coast of america, here i turned 180 and sailed back east, rounded sommerset again and sailed south past swedish waters all the way down to saint joseph town, turned north again up and rounded codrington and vent back to gustavia.
this was a fishing trip in a le gros ventre that took over 10 hours, i managed to round up over three thousand tons of fish and one sealed bottle, just one (1)