8 months ago

AD 2016 Q1


LIFE AQUATIC Below: A sand tiger shark stretches its jaw while swimming through the wreck of the Aeolus 28 miles off the coast of North Carolina. Opposite: The Aeolus is a reliable site for diving with sand tigers; they are often seen swimming inside the wreck, and diver presence does not disturb them. WRECK DIVING WITH SAND TIGERS Text and photos by Mike Gerken While most humans try to avoid sharks, the surge in popularity of shark diving in the past 10 years shows that divers are enthusiastically traveling the world intentionally seeking them out. North Carolina’s Outer Banks are a prime location for diving with sharks. Over the centuries, many ships met their demise there due to war, weather or human error as well as by becoming artificial reefs. These wrecks have morphed into prolific reef communities with abundant marine life from every link in the food chain, and sharks are the dominant predators. Drawn in by the bountiful food supply, numerous species — including blacktip, sandbar, bull and occasionally hammerhead sharks — can be found on these wrecks. But the stars of the show are the plentiful sand tiger sharks (Carcharias taurus). With small, piercing eyes that seem to stare at you from every direction and rows of ragged teeth protruding from a cruel smile, the sand tiger’s visage is reminiscent of a Hollywood villain’s. But looks can be deceiving; these sharks are actually docile and sedate animals that do not startle easily. Careful divers who respect the animals’ space will be able to achieve proximity without needing bait or chum. Because of the sharks’ mild disposition and the ease of finding them, encounters are almost guaranteed. Geography plays an important role in producing the great diving opportunities off the North Carolina coast. The Gulf Stream heads north along the Western Atlantic, eventually colliding with the barrier beaches that are the Outer Banks. In the summer water temperatures can reach 80°F, with the average on the bottom hovering in the mid-70s°F. Visibility can exceed 100 feet on a good day, and the norm is around 60 feet. The combination of warm, clear water, historic wrecks and plentiful sharks and other marine life makes for world-class diving. Even after spending hundreds of hours in the water with sand tigers, I still get a rush from being among these menacing-looking but gentle sharks. On a given dive only a handful may be on a wreck, while on another there may be too many to count. Each year in mid-July on the wreck of the Caribsea, east of Cape Lookout, sand tigers ascend from the bottom higher into the water column, where the water is clearer and warmer. On more than one occasion I have seen nearly 75 sharks, all females, gently swimming into the current in a schooling formation. It is unknown why they do this, but the sight of it is permanently etched in my mental logbook. The aggregation of sand tigers on the wrecks is most likely due to the reliable source of food the shipwrecks provide. The wrecks may also serve as navigational aids during the sharks’ migrations. Dean Fessler, educational director of the Shark Research Institute, explained it this way: “Sand tigers migrate long distances up and down the East Coast, heading as far north as Maine in the summer and south to central Florida in the winter. They detect the electromagnetic fields the wrecks emit and use them as waypoints along their route, much like we would use a GPS.” Whatever inclinations sand tigers have for the wrecks, recreational divers are happy they have them. Being surrounded by a plethora of toothy sharks while exploring a historic shipwreck makes the diving experience all the more fascinating and educational. As Fessler added, “It’s a history and biology lesson all in one.” Also known as ragged-tooth sharks or gray nurse sharks, sand tigers are found worldwide, predominantly in temperate and subtropical waters, including the Atlantic coasts of North and South America as well as South Africa, Australia and Japan. Juvenile sand tigers 40 | WINTER 2016


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