sharks really the monsters they are said to be?
||This is not a view of sharks that
most divers are likely to see - fortunately
I was one of twelve divers strung out along the 'drop off'. We had adjusted our buoyancy so that we hung motionless in the water, neither rising nor sinking. Above our heads was more than a hundred feet of clear water, below us the edge of the coral cliff, ragged with clumps of coral and giant purple sponges. Lower still, the cliff faded into the darkness of the abyss known as the Tongue of the Ocean. The water here plunged thousands of feet deep to the east of Andros Island in the Bahamas. We could see shoals of small fish and the occasional big grouper moving below us. It was a stunning view. There was not a shark in sight.
A moment later there it was. Just feet in front of me a huge Hammerhead Shark had appeared from nowhere. It must have been almost ten feet long. The shark looked at me with its tiny black eyes and I looked back. Strangely I experienced no fear, just awe. We were simply two of our Planet's inhabitants unexpectedly face to face. Moments later the big fish flicked its tail and was gone, disappearing into the blue with phenomenal acceleration. I suddenly realised that throughout the whole episode I had been holding my breath. I exhaled loudly sending a long stream of bubbles surging towards the surface and turned excitedly to my diving buddy just a few yards away. He was still gazing down at the coral, totally unaware that he had been so close to the big shark.
Later I discovered that only three out of the twelve of us had seen the fish, it had come and gone that quickly!
Such moments can make us realise that when we are in the domain of the Shark, then we are entirely at his mercy, for we can have no defence against such a fast and effective killing machine - particularly one several times bigger than ourselves.
|The Blue Shark is primarily an oceanic species growing to ten feet or more in length.
However the fact that the shark can kill us so easily doesn't mean that he necessarily will. There are thousands of close encounters between divers and swimmers every year, and yet remarkably few of them result in an attack.
Man is not a natural food for the shark and recent tests carried out in South Africa have shown that the great White Shark doesn't really like the flesh of mankind or other land-living mammals. The tests showed that it very much prefers the fatty flesh of seals and fish.
One of my responsibilities in the Bahamas was compiling reports of shark attacks for the Smithsonian Institution in Washington. Fortunately shark attacks in the Bahamas are very rare. There has certainly never been a 'Jaws' scenario. In fact it is regrettable that many peoples' perceptions of sharks are based upon such fiction.
I was called one afternoon to the Princess Margaret Hospital in Nassau to interview nineteen year old Phillip Sweeting from Andros. He had been spearfishing and had a Hogfish on his spear when attacked by a shark. There was fish blood in the water - a similar situation to that almost ten years earlier when a previous attack in these islands had occurred. With a single bite the shark had severed his arm at the elbow.
Sharks become excited when there is blood in the water - just as you or I might feel hungry when we smell good food. Furthermore sharks are attracted from a considerable distance by the low frequency pressure waves given off by a flapping and wounded fish. These waves are detected by the shark's lateral line extending from its nose down to its tail on either side. As the shark comes closer, other senses come into play. Now the shark is guided by his olfactory (smelling) sense. The shark's nostrils are on the underside of his snout and can detect minute concentrations of blood in the water. The shark uses sight for his final approach, but is probably not aware that the blood does not come from the diver. There is every possibility that the comparatively small (2 m) Lemon shark (as identified by Mr Sweeting from Bohlke and Chaplin's 'Fishes of the Bahamas') did not eat Phillip Sweeting's arm. It probably discarded it and took the Hogfish instead. At the time
Mr. Sweeting was hardly in a position to notice!
At the time of that particular attack, the U.S. navy had recorded 11 shark attacks in the Bahamas since records began. By comparison New South Wales in Australia recorded 137 attacks, South Africa had 99 and the USA had recorded 176 of which 105 had been in Florida. A tourist in Nassau is more likely to be hit by a car than attacked by a shark. In fact crossing a busy road anywhere is potentially far more hazardous than scuba diving!
|A reef shark cruises over a bed of Stagshorn Coral in the Caribbean.
The shark has inhabited the seas far longer than Mankind has walked upon the Earth. In almost all of that time, he has been the top predator, untroubled by the strange 2-legged visitor from the land. We have entered the shark's territory as guests and we must recognise that. If we behave in a way that causes the shark to attack then the responsibility is ours. We are now learning not only to live with the sharks but also how to control their feeding activity, for organised dives now attract sharks specifically to feed them.
The shark is a killer, but a very selective killer. It has evolved with the other residents of the seas where it removes the weak, the sick and the unwary. It serves to maintain the genetic viability of its prey, thereby ensuring the survival of the fittest. The shark, like every other fish has a role to play. We must respect that and not take
unnecessary chances in an environment where we don't really belong.
© R. Attrill 2000