Scientists have long had a (debatably) unhealthy fascination for potentially dangerous wild animals. A curiosity for anything with sharp teeth, claws, fangs, tusks, and an instinct for survival so strong they could easily shred you to pieces. Call it the thrill of danger, or the strange excitement stemming from being up close with some of the world’s most lethal predators.
I am no stranger to this feeling, as far as I can remember the only animals I deemed interesting were the ones I was told to be wary of. Snakes? Scorpions? Leopards? Sharks? You name it. Most people rightfully fear such animals, however, there is a difference between fear and cautiousness, and for many years, a lot of these animals have been subjected to their ‘bad press’, being unfairly portrayed as cold-blooded killers, man-eaters, and countless other names. The stigma revolving around nature’s ‘killers’ has lasted for centuries, and is still being perpetrated today. No wonder modern society has an aversion towards these animals.
40 years ago, Spielberg produced “Jaws”, a thriller depicting Great White Sharks as nature’s most cruel, cold-blooded and blood-thirsty killers in the sea. I can remember, watching it as a child, being terrified of being stuck on a boat on the open ocean, anticipating the beast to launch its attack any minute. Then I grew up, started studying biology, and realised the horrible stigma that the film has generated on modern generations. The “Jaws stigma” is a real thing, and has been qualified several times in conservationists’ attempts to educate the public about white sharks.
White sharks are actually quite peaceful creatures, which do not generally initiate attacks on humans. White sharks, due to their energetic requirements, prefer feeding on seals, which have a large layer of fatty insulatory cells called blubber, very energy-rich. Humans, in comparison, are far too skinny and bony to be deemed interesting prey. Due to their curious nature, white sharks may occasionally approach swimmers and surfers (surfers especially due to their similarity with the shape of a seal when viewed from below), and take a “taste” bite. Sharks investigate a lot of their environment through their gustatory senses, and thus, after “tasting” a human, they generally deem the prey uninteresting, and leave. This is the reason why, often, reported white shark attacks consist of limb amputations, and it is speculated that deaths are rarely due to the sharks consuming humans, but rather caused by rapid blood loss following bites.
I spent the summer working with White Shark Projects, a cage-diving company operating in Gansbaai, in the Western Cape region of South Africa. Cage diving in South Africa began in 1991, as the numbers of free-ranging white sharks fell to a critical low the government realised the urgent need to conserve the species. A ban was passed on the extractive fishing of white sharks, and ecotourism was used as a platform to generate capital for conservation, as well as a means to educate the wider public. Cage-diving has since become very popular throughout the globe, and generally diving and swimming with sharks has developed as a lucrative industry, alongside whale-watching and other animal viewing operations worldwide.
There are 3 sites where cage-diving is allowed in South Africa: Gansbaai, Mossel Bay and Cape Town, divided between a dozen tour operators.
Operators leave harbour in the morning, usually between 7:30 and 8:30AM, and go off to the first dive site of the day. Once the boat is anchored, a member of the crew starts chumming to attract the sharks. Chumming consists in preparing a scent trail for the sharks to follow, by crushing up fish and adding some seawater to dilute the fish blood and oils, and throwing it progressively overboard so the currents may carry the trail further (see below).
Any shark that encounters this trail will immediately be able to follow it until its source – the boat. Once (and if – sharks may not come at all) a shark has been spotted within the vicinity of the boat, another crew member will throw in a rope in the water, with a bait attached to a float, which they drag alongside the cage where the divers are, to attract the shark within viewing range of the divers.
Now, if you’ve looked at videos online of white shark cage diving, people tend to post the most impressive sightings they have, which are usually where the shark is perceived to be aggressive: breaching out of the water, jaw open, teeth protruding… we’ve all seen those before. The truth is, those impressive encounters are quite rare. Sharks are usually a lot calmer, swimming around the boat slowly, and may not even attempt to bite the bait at all. Their behaviour varies depending on age, sex and individuals (Towner, 2013) and as such sharks have what you may call personalities, some are curious and come take a glance at the strange creatures in the cage, others are a little more feisty and try to catch the bait several times.
In fact, we know very little about great white shark behaviour, limited to quantify only what can be observed around the boats, and some proxy data using a variety of tags. White shark research is costly, time and effort-consuming, and some studies may run for years, even decades, before they reach any sort of conclusion.
What we do know, however, is that white sharks are inquisitive animals, which display a range of complex behaviours, like undertaking trans-oceanic migrations , to showing intricate dominance hierarchies . Far from being the bloodthirsty killers we know from movies, there is still a lot we have to learn about them, and hopefully as people learn, the fear will disappear, and we can all work together to save this species from extinction. More than 100 million sharks are slaughtered every year , and great whites are no exception: targeted for their jaws (which can sell for more than 10,000$ on the black market), white shark population worldwide has declined to 2000-5000 sharks, ranking them as endangered on the IUCN Red List .
The importance of conserving apex ocean predators cannot be stressed enough, and their rapidly declining population could cause a global disequilibrium in marine food webs, impacting marine communities worldwide. Not only would this be an ecological disaster of a tremendous scale, but the human and economic impacts of the extinction of top ocean predators (like great white sharks) would also be severe. The exact scale of such impacts is difficult to determine because of all the factors involved, but logical speculation would suggest that it could result to changes in fish stocks – affecting fisheries and possibly threatening food security. And this is, of course, just a glimpse of the picture we can expect if we continue our current trends. Sharks aside, almost every ecosystem on this planet is threatened, from deforestation to global warming, the causes are numerous, but all have one thing in common: they are man-made. If we want to preserve the ecosystems we depend on, something needs to be done, and it needs to be done fast.
Question is: how can you help?
 Bonfil et al. (2010) Large scale tropical movements and diving behaviour of white sharks Carcharodon carcharias tagged off New Zealand. Aquatic Biology. 8 pgs 115-123
 Martin and Martin (2006) Sociable Killers. Natural History. 115 (8) pg: 42-8.
 Towner et al. (2013) Environmental influences on the abundance and sexual composition of white sharks Carcharodon carcharias in Gansbaai, South Africa. PLoS ONE 8(8) doi:10.1371/journal.pone.0071197