To expand on john's comment above, and the lionfish discussion; the only place in the area that I know you can spearfish is (as John said above) Pedro Bank, which is something like 40 miles off shore. The boats that you'll find in and around TB aren't the type that I would feel comfortable going so far offshore in. It's not uncommon for TB fishermen to die at sea, they fish very small boats, usually with a single outboard engine, often no emergency floatation. Just so you can make a somewhat informed decision. You might want to check out Little Bay, which is about a half hour south of Negril if you're serious about wanting to spearfish for them.