Some Sharks May Bite in Self-Defense Rather Than Aggression

Shark attacks are often sensationalized, reinforcing the perception of sharks as mindless predators. However, new research conducted in French Polynesia indicates that a small number of shark bites may be defensive reactions triggered by human behavior perceived as threatening. These findings challenge long-standing assumptions about shark motivations and call for a shift in how such incidents are interpreted.

Instinct to survive

An international team of researchers documented 74 shark bites in French Polynesia between 2009 and 2023. Of these, four cases—around 5%—were likely self-defense responses. These incidents typically occurred when humans engaged in activities such as spearfishing or attempting to touch the shark, actions which may be viewed by the animal as aggression.

“We show that defensive bites by sharks on humans—a reaction to initial human aggression—are a reality and that the animal should not be considered responsible or at fault when they occur,” said Dr Eric Clua, a shark specialist and researcher at Université PSL and lead author of the study published in Frontiers in Conservation Science. “These bites are simply a manifestation of survival instinct, and the responsibility for the incident needs to be reversed.”

Disproportionate reaction

Sharks may react with what Clua terms “disproportionate force,” producing non-lethal yet sudden bites with little or no warning. These behaviors are similar to defensive responses in terrestrial animals, such as bears or cassowaries. Species like the gray reef shark, known for their territorial nature, are especially prone to such reactions.

“The sharks’ disproportionate reaction probably is the immediate mobilization of their survival instinct,” Clua said. “It is highly improbable that they would integrate revenge into their behavior and remain above all pragmatic about their survival.”

Global parallels

To assess how common this behavior might be globally, the researchers analyzed nearly 7,000 shark bites from the Global Shark Attack File, focusing on cases labelled as “provoked”. They found 322 instances that may have involved self-defense, aligning with the 3-5% observed in French Polynesia. 

Respectful distance

The key message from the study is clear: Avoid physical interaction with sharks. Even attempts to assist a stranded animal may be perceived as a threat. “Do not interact physically with a shark, even if it appears harmless or is in distress. It may at any moment consider this to be an aggression and react accordingly,” Clua warned. “These are potentially dangerous animals, and not touching them is not only wise, but also a sign of the respect we owe them.”