Cage Diving and the Great White Shark by Glen Ashton

All living beings emit electricity and our own private magnetic field is probably as unique as our fingerprint. Biological electricity – or bio-electricity - has been shown to be critical for maintaining the most basic functions of life, such as replication of DNA and even the fertilization of eggs by sperm. We are not only controlled by our internal chemical processes; we are also amongst other things, electrical beings.

Each animal emits a similar electrical pattern; this is largely a function of the physical shape, size and health of the animal be it a seahorse or a whale, as the case may be. But very few species have specialized organs to actually sense the electromagnetic fields emitted by other animals. These receptors are absent in most land animals but are common in aquatic life.

The animals with the most sophisticated electrical sense organs are cartilaginous fish or Elasmobranches, the family that includes sharks. Sharks have highly developed electrical sense organs called the Ampullae of Lorenzini. These are particularly concentrated around the snout and this is notable in the Great White, evident from the blackhead-like spots around the nose.

This is why these massive apex predators can be rendered as helpless as a kitten for a few moments, by grasping their snout when they stick their head clear of the water to look around, as they are known to. Grasping the organs of Lorenzini shorts out a sensory loop on the shark, incapacitating it. This is also where the received wisdom originates that you should knock a shark on its nose when attacked.

Several studies show that sharks rely on this electromagnetic sense for feeding to a greater extent than any other senses, even their acute sense of smell. Sharks can sense a voltage of as little as 4 nanovolts, or 4 thousand-millionths of a volt. This is a tiny current. People crank out a lot more power than that. This ability gives sharks their edge in dirty water and in situations of low light. It may also explain why large sharks do not commonly swim in kelp, as it bumps their noses and may also serve to 'earth' their Lorenzini receptors.

So what has all of this got to do with the recent shark attacks? Everything. The crux is this: Sharks have become habituated, through Pavlovian conditioning, to recognizing humans as the only electromagnetic force associated with the chum used to attract them to dive boats. As sharks are lured and fed dead fish, which emit no electromagnetic field, no other animal electromagnetic field is present, beside humans.

It is not just that sharks associate these boats with chumming, nor is it that the shark makes some connection with the humans being responsible for the chumming as many suppose, in what is really an illogical conclusion. The reality is that every time sharks are lured to the dive boat, the only electromagnetic 'life force' in the water is that of tourist humans clad in wetsuits, surrounded by the smell and taste of food. A cynic could say that this is akin to teasing great whites, and perhaps it is.

A local shark diver boasts he has lured over 5000 sharks to his clients in this way. It can safely be assumed that there are not 5000 great whites in the area, the number is probably less than 500. While Great Whites are known to migrate for certain parts of the year, they have also been shown to be quite territorial. It is therefore highly likely that certain specific sharks have been attracted to this - and perhaps other shark tourism boats in the region - many times over the past few years.

Like surfers, these shark diving tourists wear wetsuits when the shark is being excited and fed in the vicinity. So both divers and surfers would emit a similar electromagnetic pattern. Again, Pavlovian association has a high likelihood of imprinting the association of food with this particular electromagnetic field. This Pavolvian association may be the real reason why we have had three shark attacks in the last 18 months in Cape Town, two on surfers and one on a diver.

There is the need to build a base of empirical evidence from this informed background. We know that electrical fields can repel sharks, in fact electronic 'invisible cages' are now commercially available, which rely on the electrical sensitivity of sharks. From this, it would be most interesting to find out if electrical fields that attract sharks can be devised. Experiments have already shown that small sharks will attack a magnet that exhibits characteristics similar to its prey, so a start has been made.

It should also be entirely feasible to provide electronic masking of some pattern around the cages from which tourists view the sharks. Further research along these lines would go a long way to building a system that would stop the habituation the sharks to human electrical fields when food or electrical attractants are simultaneously present and hopefully make shark cage diving a lot more sensible than is presently the case.

Craig Bovim, who on Christmas eve 2002 had a close encounter of the worst kind with a great white off Scarborough said; "Its insane to be allowed to bait apex predators to attract them to swim in close proximity with people and then not expect them to associate food with people." He is dead right. It is time to reconsider how we interact with one of the few animals capable of killing people with ease. Bovim says we are not allowed to attract baboons, let alone lions or killer whales with food, so why are we allowed to attract sharks like this?

We urgently need to look at solutions to how we interact with great white sharks and meet the challenges of this poorly understood area of wildlife conservation.

The article above was first published by Independant Newspapers.