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A Blacktip Reef Shark.
Photo: Genevieve Johnson

December 20, 2002
Besieged by Blacktip Reef Sharks
  Real Audio

Log Transcript

This is Genevieve Johnson speaking to you from the Odyssey in the Indian Ocean.

It is with much regret that our time researching whales around Aldabra and in the Seychelles is coming to an end. The Odyssey is now travelling out to sea in search of sperm whales for the last time. There has never been a dedicated search for this species around the Aldabran group and the results of our research are providing an entirely new data set for this region.

However, we were not to leave Aldabra without a final and unforgettable wildlife spectacle, a fitting farewell from this World Heritage Site and wildlife haven. As the crew waded out from shore into the ankle deep shallows toward our dinghy, we were literally besieged by sharks. These were small four to five foot long blacktip reef sharks. To see any shark in its natural habitat is exhilarating, but to see so many in one of the most unspoiled locations in the world is humbling.

At first, only two or three approached us. Within minutes, their numbers had exploded to about thirty as they streaked toward us from a distance. Were they simply curious at the sound and vibrations we made as we walked through the water, or were these sharks making some kind of association between us and a potential snack? The sharks appeared more curious than aggressive which calmed our nerves to some degree. It was impossible to keep an eye on all of the sharks at once, which were darting around and between our legs from every direction. We all tried our best to exude a sense of relaxation in front of these sharks, yet the occasional bump on the ankle from behind was enough to encourage some of us to jump in the air and try to walk on water.

Chris and Yasmin grabbed their underwater cameras and lay on their stomachs in the shallows. The sharks seemed to be immediately attracted to them. Some swam directly toward them at high speed, their noses ricocheting of the lenses. They both commented on how shocked they were at the strength of these relatively small sharks.

Blacktip reef sharks swimming in the shallows outside the Aldabra Research station.
Photo: Genevieve Johnson

Yasmin Hunt - Odyssey Deckhand:

"We were very lucky to have this encounter with so many black tips. Even though these sharks are relatively small, they are powerful, unpredictable and deserve our respect. I was hoping that someone was watching my back while all this action was happening."

Chris Johnson - Odyssey Producer/Photographer:

"Lying face down, looking through my camera, with my stomach scrapping against the coarse sand, I had black tip reef sharks coming at me in all directions. Even in such shallow water, they cruised along with so much ease and power. Without warning, one swam directly at my camera lense and did not stop. It bumped it with such surprising force, it left me wondering if he was trying to show me who was the boss."

Genevieve Johnson

Perhaps the sharks were attracted by the tiny electrical impulses given off by the metal camera housings. Sharks are gifted with senses we have never attained. The shark's electricity sensing devices are clusters of tiny pores scattered around the snout and head called ampullae of Lorenzini. An actively hunting shark like the blacktip has about 1,500 such electro-receptors. The ampullae are remarkably sensitive and are sufficient to detect the electrical impulses emitted by the muscle activity of their prey. A function that has only been understood since the 1960's. Presumably in this situation the shark may mistake the impulses emitted from the metal camera housings for a prey animal. A little nerve racking, but it makes for some great pictures.

Blacktips are the most commonly found sharks around the coral reefs and lagoons of tropical atolls together with grey reef sharks and whitetip reef sharks. It is difficult to mistake this species for any other. Both their dorsal and caudal fins are marked with a thin black tip. They also have a conspicuous white blaze along their flanks. Like all sharks they are ancient yet complete in their design, the result of over 300 million years of change and adaptation.

Chris and Yasmin got very close to the blacktip reef sharks.
Photo: Genevieve Johnson

Blacktip reef sharks are common in Aldabra, but are possibly declining in the overall scheme of the ocean ecology due to pressures from global fisheries. As sharks continue to disappear from the world's oceans, our chances of encountering them in a natural, unexploited state such as this are also fading rapidly. As demonstrated in this year's SUBIOS festival in the Seychelles, it is the children here who are leading the way. They are calling for the protection of sharks by highlighting the plight of the worlds dwindling populations.


Click here to read more about the 2002 Seychelles SUBIOS Underwater festival.

Written by Genevieve Johnson

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