About Guy:Guy Harvey 

 On any given dive in the Cayman Islands the chances of encountering any species of shark are very slim. Why is this? The primary reason is that most of the large coastal and ocean sharks have been caught in the last 50 years by long line fishing efforts directed at tuna and swordfish and more recently at sharks themselves.

 Nowadays sharks are kept by such industrial fishing operations which remove the fins and sell them to Oriental interests. Many species of ocean going sharks such as blues, tigers, hammerheads, makos, threshers  and oceanic whitetip sharks pass by our islands and sea mounts, and have extensive ranges so are considered high migratory species. These have been heavily fished by high seas long lining operators. Other species exhibit more site fidelity and have a home range such as the Caribbean reef shark and the blacktip shark, which are the species we are more likely to encounter here.

 Even then, I have not seen a black tip shark while snorkeling or diving in Cayman. Caribbean reef sharks…for sure, they are the most common shark around the Cayman Islands. Not until the current shark population study was conducted by the Dept of Environment, the Overseas Territories Environmental Programme and the Guy Harvey Ocean Foundation did I finally see a blacktip shark here. They were caught at night in North Sound in behind the barrier reef in setting mini long line gear to catch, tag and release local sharks.

 To the untrained eye they are similar to the reef shark, typically six feet long, with a large dorsal fin and black tips on the pectoral fins. They have a pointed nose and compact body built for speed. They grow to eight feet and are found worldwide in tropical and subtropical waters. Over continental shelves the blacktip shark feeds on schooling fishes such as sardines, jacks and mackerels. In the Pacific in Panama I have filmed them feeding on green jacks and scads along with schools of yellowfin tuna and spotted dolphins. In South Africa, blacktips are major predators on the annual sardine run. In Florida, the blacktip shark and the similar looking spinner shark are common near shore predators of mullet, sardines and jacks. They are frequently caught by anglers fishing from the beach.

 Around the Cayman Islands, blacktips are found in the shallow sounds and flats bordered by mangroves, and they are primarily fish eaters but will also consume stingrays and crustaceans. There is a very narrow shelf area here, so the black tip sharks keep to the flats and back reef areas that provide most food. So far a few blacktips have been tagged with acoustic transmitters to track their movements around and between the Cayman Islands.

 Blacktips are common in the Bahamas where long lining has been banned for the last 20 years and they form part of the exciting shark interactive programmes that net the Bahamian economy up to $70 million per year.

 However their reproductive strategy keeps populations at a modest level. They are viviparous (give birth to fully formed young), with a gestation period of up to a year and giving birth to two to six pups every two years in protected shallow water environments away from predatory bull, tiger and hammerhead sharks.

 In complete contrast, the oceanic whitetip shark is found roaming the open blue water and rarely comes close to shore. In looking at their shape you know they are designed for the open ocean habitat. They are large animals with robust bodies typically about eight feet but growing up to twelve feet long. They are characterised by their very long, broad pectoral fins, with blotchy white tips as with all their other fins.

 They have been a primary target in the shark fin trade and now their populations may be as low as one per cent of their pre-exploitation levels in the western Atlantic. They used to be the most abundant “large” animal (over 100 pounds) on the planet. Found in all the world’s tropical oceans, typically they associate with flotsam and those species of fish that congregate around flotsam and with migrating marine mammals such as whales and dolphins. They are usually solitary and slow moving, conserving energy between meals which may be weeks apart. Often they are accompanied by pilot fish and rainbow runners. They are very inquisitive and will investigate anything floating looking for carrion. Tiger sharks exhibit similar behaviour.

 The only time we see oceanic whitetips is when we go fishing offshore looking for dolphin fish, tuna and marlin. They may be encountered around a school of dolphin fish and rainbow runners in association with a floating log or shipping pallet. Off Jamaica I have seen oceanic whitetips following pilot whales and sometimes spotted dolphins. During the recently held Cayman Islands International Fishing Tournament, Oliver Dubock, a PhD student working with the DoE and OTEP, tagged two oceanic whitetips caught by anglers participating in the tournament with electronic tags to learn more about their natural history and migrations. Knowing that this species spends a lot of time at or near the surface, the satellite tags will pin point their migrations around the Cayman Islands. More information will be forthcoming. We know very little about the life history of this species which is on the verge of extinction and is listed as “critically endangered” by the IUCN.

 In spite of their inquisitive nature and reputation, open water shark interactive dives with this species are safely conducted in the Caribbean and Bahamas without incident, but divers are cautioned to interact with the oceanic whitetip with extreme caution.

 If you are diving, snorkelling or fishing and encounter one of these rare species, please call the Department of Environment and let them know the location, date, species, approximate size and sex. If you catch a blacktip or an ocean whitetip shark, then take the necessary measurements and photos as well as a tissue sample (fin clip) and then please release them alive.

 It is our collective responsibility to conserve the marine environment and maintain the biodiversity of the planet. Fish responsibly and dive safely.
Guy Harvey PhD.    
www.guyharvey.com