A new study, led by Dr Eric E. G. Clua, has analysed decades of shark bite incidents in French Polynesia and found that certain human activities—especially spearfishing and handling fish traps—can trigger defensive bites from sharks. These bites are different from predatory attacks in that they result from a situation in which the shark feels threatened, often after a human has behaved aggressively towards it, whether intentionally or not.

Unlike predatory bites, which involve heavy tissue loss and are often fatal, self-defence bites tend to be quick, superficial and rarely deadly. Sometimes, a shark will deliver multiple bites in response to the initial threat.

Sharks may sense threats before they happen

Importantly, the study also notes that sharks can react defensively before an actual attack happens if they sense danger—a behaviour marked by clear warning signs that divers and fishers should learn to recognise.

Experts warn that trying to handle or “rescue“ a distressed shark could lead to unintended injuries, even for well-meaning divers. They also call on the media to stop sensationalising these incidents as unprovoked “attacks“, arguing that accurate reporting could help change public attitudes and promote shark conservation.

More explanations for shark bites

Clua is the researcher who challenged the long-standing Mistaken Identity Hypothesis (MIH), which claims that sharks bite humans because they think they are prey. Although the MIH had gained popularity since its introduction in 1974, Clua argued that it lacked solid evidence and oversimplified shark behaviour. Studies showed that factors like water clarity and wetsuit colour did not affect them. Furthermore, the MIH took only vision into account, whereas sharks have advanced sensory abilities specifically evolved for use underwater, ones that they likely rely on just as much as, if not more than, vision.

Clua proposed that most shark bites stem from natural exploratory behaviour, with sharks investigating unfamiliar objects, including humans, and not mistaking them for prey. Given that sharks are cautious and curious, and are not known to make mistakes, this explanation is widely considered to be a better explanation for what is generally observed. Though an exploratory bite by a great white shark might leave a mortal wound on a person, the shark leaves and does not return to eat him.

The bottom line for divers

Respect the shark’s space, stay calm and be aware of how your actions might be seen from a shark’s point of view.