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 fifty 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 Asian 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 highly 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.
To the untrained, eye blacktips are similar to the reef shark at 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 can grow to eight feet and are found worldwide in tropical and subtropical waters. Blacktip sharks feed over continental shelves on schooling fish such as sardines, jacks and mackerels. On the Pacific side of 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, and 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 are primarily fish eaters, but will also consume sting rays 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 the most food.
An Oceanic Whitetip Shark which ate a trolled bait intended for marlin. Photo Courtesy of Richard Gibson
In complete contrast, the oceanic whitetip shark (OWS) 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 characterized 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 1% of their pre-exploitation levels in the western Atlantic. They used to be the most abundant “large” animal (over 100lb.) 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 behavior.
The only time we see OWS 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 OWS following pilot whales and sometimes spotted dolphins. During the recently held Cayman Island International Fishing Tournament, Oliver Dubock, a PhD student working with the DoE and Overseas Territory Environment Programme (OTEP), tagged two OWS (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 International Union for Conservation of Nature (IUCN).
Open water shark interactive dives, with this species, are safely conducted in the Caribbean and Bahamas without incident, in spite of their inquisitive nature and reputation. But divers are cautioned to interact with the OWS with extreme caution.
If you are diving, snorkeling or fishing and encounter one of these rare species, please call the Dept. 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
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