Graham,
Have been visiting st. marteen for quite a few years now. what part of the island are you moving to. the dutch side has "Lee's" it is not only a great restuarant but has incredible information about local fishing hot spots. A few people will attemtp to persuade you to go to "Bobby's Marina" for information but trust me "Lee's " is the most valuable info spot. In Marigo, on the french side I have had very exposure to fishing........... great place to eat and drink ( and the beaches aren't bad either).
gs