The official website for The Settlers of Catan

Question about “Explorers & Pirates” Expansion Fish shoal - If your ship has no more movement points left and is pointing towards a fish shoal hex, and then you successfully roll for a fish shoal, can you load it immediately?

Answer

Yes, you don't need movement points to catch a fish haul and load it onto your ship. The only requirement is that your ship either point to a fish shoal hex with a fish haul or stand on a sea route adjacent to that fish shoal hex.