Captain Crawfish is lurking near the Pirate Outpost and will
occasionally attack you. You must flee because you cannot trick him
into hitting the reefs like other pirates, and you cannot outshoot
him with smaller ships.
When you have recovered all 5 pieces of the island map, the new
island Skullduggery will appear, and you can easily find the
Captain near it. You will need a Phoenix Warbird, the Shipwright,
and the Cannoneer to defeat him.