You ask a very interesting question that has many possible answers. It sounds like you might be doubtful about the explanation that St. Croix sharks are smarter. I don't blame you! There is no evidence that sharks from one region are smarter than others. Your insight into the issue of water clarity is probably an important one. One thing you may not know is that by far the largest number of attacks in Florida occur on surfers (that is also true in other places in the world). Waves and crashing water in the surf zone may make it hard for a shark to see what it is attacking. Is surfing a popular hobby in St. Croix? It may not be as common as in Florida, California or Australia. But, there are other things to consider as well, such as the size of the populations of people and of sharks. I am not an expert on sharks, so I would recommend that you consult the International Shark Attack File (ISAF) website at
sharks

That page has just about everything you could want to know about sharks and shark attacks around the world! There are also pictures and information on different species of sharks. It is a terrific place to learn more about a subject you're obviously interested in, and perhaps it could launch your career in shark science!