With the blue void beneath us, we drifted along the vertical expanse of the coral wall
surrounded by sharks. Sometimes, as many as five or six would weave into view.
For obvious reasons, we tried to keep our backs against the coral face.
Photo: Genevieve Johnson
December 18, 2000
Gray Reef Sharks
This is Roger Payne speaking to you from the Odyssey in the Tropical Pacific. Since entering this area eleven weeks ago, we have been fortunate enough to visit some of the few remaining pristine coral reefs in the world-reefs supporting thriving, healthy ecosystems where humans have not depleted the abundance and diversity of life, and where, by the large numbers of apex predators such as sharks, we can see that we are entering a fit and undamaged wilderness.
The other day, the crew took the dingy out just seaward of a deep drop-off by a spectacular coral wall, and turned off the engine.
They were immediately surrounded by gray reef sharks: one of a large family of requiem sharks; sleek, swift creatures that grow up to 6 feet long and which are found throughout the tropical seas Gray Reef Sharks are distinguished by a broad dark band along the trailing edge of the tail. They make their homes along coral reefs feeding primarily on small fish, cephalopods, and crustaceans such as lobsters and crabs. They mature at seven years and have a maximum life span of about 25. They are one of the most aggressive sharks, but usually give warning of their intentions by a distinctive display termed threat posturing. Aggression towards humans appears to be territorial rather than motivated by hunger. An attack usually results in a single nasty, but non-fatal bite. However, one needs to be careful, for when present in large numbers, they are quick to go into 'feeding frenzies'.
As the crew entered the water, the sharks materialized from all directions to investigate. They circled the boat as well as those of the crew in the water who had wandered some distance away, but after about 15 minutes they began to drift off one at a time, presumably to resume their normal daily activities. Even so there was only an occasional visitor, his curiosity not yet assuaged, or perhaps having trouble remembering what it was he had just seen, that came by to investigate. The crew wasn't worried though because they had encountered this shark species on several occasions, though never before in such numbers.
Some of the Odyssey crew dove off the reef wall later in the afternoon, again encountering Gray reef sharks. They found it possible after a while to recognize individual animals by distinctive blotches, scratches and scars. The sharks appeared to have their own territories and during the crew's 45 minute dive, they saw the same sharks patrolling the same areas... which supports the results of telemetry studies of this species which have shown that they are not ceaseless wanderers like so many of their relatives, but visit and patrol specific regions of the same reef each day.
But let Genevieve Johnson describe the experience of this dive for you:
With the black void beneath us, we drifted along the vertical expanse of the coral wall surrounded by sharks. At times 5 or 6 would weave into view. For obvious reasons, we tried to keep our backs against the coral face. The sharks seemed entirely unhurried, but their muscular bodies advertised their potential for explosive power when necessary. It wasn't until we surfaced and begun to make our way back to the boat we began to understand why they had attained the reputation of being aggressive. What truly sets this species apart is the remarkable body language it exhibits when you invade its space. This defensive behavior serves as a warning which one is well advised to heed once you have learned to recognize it.
While we were swimming towards the boat looking downwards, one of the sharks dropped its pectoral fins strait down and raised its snout, arching its back and swimming with an exaggerated, weaving motion. It was clear enough what it's message was, and we all decided to leave the water as quickly as possible. But we had a problem: the agitation among the sharks spread, and it was difficult to keep our eyes on all of them at once. Suddenly Brian yelled at me underwater when a shark I hadn't seen streaked up from below at me. Fortunately when I aimed a kick in its direction it left.
For hundreds of millions of years, sharks have survived virtually unchanged and unscathed, ruling supreme in the world's oceans. Unfortunately the party's now over for these predators. Late maturation and low reproduction rates makes them highly vulnerable to over-exploitation. Sharks are being killed at alarming and completely unsustainable rates worldwide. Unfortunately many unregulated fisheries continue and often it's just the fins that are taken. Shark fins are highly prized in many Asian countries for making soup. Some fishermen slice the fins off live sharks, then throw the rest of the shark, still very much alive, overboard to drift away and die slowly.
Some countries are slowly recognizing the threat we pose to these apex predators and have begun to implement shark management strategies. But we have a long way to go if we are ever to see the recovery of these extraordinary animals, to the point where we can see and enjoy them again in all but a few of the wildest places. Sure, they're a bit scary at times, as Gen points out, but so is life. And after all she is still with us and unscathed.
This is Roger Payne speaking to you from West of the International Date Line and just South of the equator.
Log by Roger Payne & Genevieve Johnson