Image Credit: Sharkcrew, CC BY-SA 4.0, Image Cropped
In February 2022, a British swimmer was killed by a great white shark (Carcharadon carcharias) near Sydney, Australia. Unsurprisingly, this gained significant media attention. State authorities launched a search for the culprit, with the aim of culling/relocating it away from people. This plan would seem, on the surface, to make perfect sense – shark ate human, make it go away. Yet this logic is largely based on a widespread misconception, and an outdated theory that science has long since abandoned.
If we go back a little further in the history of shark-human interactions, we come to July 1916. Over twelve summer days, the coast of New Jersey was the site of five incidents, four of them fatal. This story itself you may not know, but the film (and book) it is often widely cited as inspiring you certainly will: Jaws.
The evocative taglines and reused assets of the Jaws posters (Image Credit: Universal Pictures)
Less prominent in popular culture, but similarly inspired by this event, was the “rogue shark” theory. Popularised by Australian surgeon Dr Victor Coppleson between the 1930s and 1950s, it suggests “the guilt, not of many sharks, but of one shark”. It was built on the widespread concept of sharks as “man-eaters”, which dates at least as far back as the mid-1800s. Coppleson believed that the majority of sharks behaved “normally”, while “rogue” sharks were “vicious”, and “patrol a certain area…for long periods”. Such a shark, he further stated, “must be hunted until it is destroyed”.
You may note that this theory seems remarkably similar to the plot and characterisation of Jaws, painting a picture of a villain intent on the destruction of human life. But one is a classic of creature-feature cinema, and the other is supposed to be a serious scientific theory. And therein lies the – rather glaring – problem.
Innocent Until Proven Gillty
In terms of evidence, perhaps the easiest place to start is with the events that inspired the whole idea. The five incidents occurred within twelve days, progressing northwards up the coast of New Jersey. A short time frame, and a (relatively) localised area. This led some scientists to conclude that this was likely the work of one individual, conducting a tour of violence up the coast. If a decent defence lawyer had been present, however, I suspect he would have called this evidence circumstantial at best.
A juvenile great white was also caught in the area around this time with human remains in its gut. So now there’s some hard evidence, supporting a perception of the crimes and the culprit. Except, perhaps not.
Three of the incidents occurred in brackish water – the domain, more typically, of the bull shark – and two in oceanic water. This could suggest at least two individual sharks, of separate species, were involved in the incidents. This, obviously, does not completely invalidate the theory, and remains a matter of some (rather futile, over a century later) debate.
Great White Lie
According to George Buress, of the International Shark Attack File (ISAF), there are only two or three cases in the past three centuries where it is thought likely that an individual shark has been responsible for multiple incidents. Only one of these is backed up by reasonable proof, and the ‘multiple’ attacks in this incident took place over 5 minutes, not the sort of days or weeks timeframe the rogue shark theory was associated with. This leads us to alternative, and in many cases more logical and better supported, theories as to why these incidents occur.
Perhaps most obvious and self-explanatory, a considerable proportion of shark attacks (35% of confirmed shark-human interactions in 2021) are considered “provoked” by the ISAF. If someone starts prodding at a shark, no-one should be surprised if they get bitten. However, the simple unprovoked/provoked dichotomy widely used by the ISAF and elsewhere isn’t always particularly satisfactory. We do not understand enough about shark behaviour to draw a clear line under what counts as provocation. Would a shark perhaps view a person swimming too close, or above it, as a threat?
Numerous other theories have been proposed, and in 2014 John West, curator of the Australian Shark Attack File, summarised these in a single paper. He suggested that all the theories could generally fit into three broad categories; a) hunger, b) curiosity and c) aggression.
Most such theories are difficult to properly study and empirically assess, for obvious ethical reasons. However, much of the support for these theories comes from taking what we do know about shark behaviour and ecology, and the context of specific incidents, and drawing more informed conclusions from there.
For example, the majority of “unprovoked” incidents are classed by the ISAF as “hit-and-run” attacks. Many of these incidents occur in turbid, murky water, such as surf zones. In these conditions, it is easy to see how erratic splashing, shiny and reflective accessories, and contrasting colours could lead a shark to mistake a person for a more typical prey animal. These incidents also rarely involve repeat bites, with sharks typically moving on rapidly after finding the target not to their tastes.
We’re going to need a bigger theory…
In conclusion, understanding what leads to shark-human interactions, in order to better understand shark behaviour and reduce such incidents, requires proper investigation of the complex contextual factors surrounding such occurrences.
Scientific consensus, however, seems to be made up, at least regarding “rogue” sharks. Jaws was never intended to be a documentary, and we should stop treating it like one. The idea of the “rogue” shark, and language like it and “man-eater”, promote an unsubstantiated, malicious, criminalised perception of shark behaviour. This perception remains widespread, politicised and influential, despite simply not being backed up by the evidence.
The reality is that shark “attacks” remain incredibly rare, at an average of roughly 72 “unprovoked” incidents, and five fatalities, worldwide per year since 2016. For comparison, over one year between 2017 and 2018, 218 sharks were killed in culling and defence programs in Queensland, Australia, alone! While improvements have been made, sharks need us to change the way we view and discuss them, as our history together makes it abundantly clear that we are a far greater threat to the existence of sharks than they are to any single one of us.
Ben Bluck is a soon-to-be PhD student at the University of Southampton. He is broadly interested in almost everything to do with behavioural ecology and marine biology, especially sharks. You can find him being inactive on Twitter here (@anendemicshrub).