The only restrictions on the USVI are
Cittarium pica: must be over 4in in diameter
Strombus gigas: must be over 9in in length.
I really dont have any good places on St. John, but I can give you many
places on St. Croix. Please let me know if you want the info as I am writting
this at 12am and my roomates are all asleep and my typing might wake them up
(god knows how many times they woke me up coming in at 2am tanked)
Sarah Watson