Types of attacks
Shark attack indices use different criteria to determine if an attack was “provoked” or “unprovoked.” When considered from the shark’s point of view, attacks on humans who are perceived as a threat to the shark or a competitor to its food source are all “provoked” attacks. Neither the International Shark Attack File (ISAF) nor the Global Shark Attack File (GSAF) accord casualties of air/sea disasters “provoked” or “unprovoked” status; these incidents are considered to be a separate category. Postmortem scavenging of human remains (typically drowning victims) are also not accorded “provoked” or “unprovoked” status. The GSAF categorizes scavenging bites on humans as “questionable incidents. “The most common criteria for determining “provoked” and “unprovoked” attacks are discussed below:
Provoked attacks occur when a human touches, hooks, nets, or otherwise aggravates the animal. Incidents that occur outside a shark’s natural habitat, such as aquariums and research holding-pens, are considered provoked, as are all incidents involving captured sharks. Sometimes humans inadvertently provoke an attack, such as when a surfer accidentally hits a shark with a surf board.
Unprovoked attacks are initiated by the shark—they occur in a shark’s natural habitat on a live human and without human provocation. There are three subcategories of unprovoked attack:
- Hit-and-run attack – usually non-fatal, the shark bites and then leaves; most victims do not see the shark. This is the most common type of attack and typically occurs in the surf zone or in murky water. Most hit-and-run attacks are believed to be the result of mistaken identity.
- Sneak attack – the victim will not usually see the shark, and may sustain multiple deep bites. This kind of attack is predatory in nature and is often carried out with the intention of consuming the victim. It is extraordinarily rare for this to occur.
- Bump-and-bite attack – the shark circles and bumps the victim before biting. Great whites are known to do this on occasion, referred to as a “test bite”, in which the great white is attempting to identify what is being bitten. Repeated bites, depending on the reaction of the victim (thrashing or panicking may lead the shark to believe the victim is prey), are not uncommon and can be severe or fatal. Bump-and-bite attacks are not believed to be the result of mistaken identity.
An incident occurred in 2011 when a 3-meter long (~500 kg) great white shark jumped onto a 7-person research vessel off Seal Island, South Africa. The crew were undertaking a population study using sardines as bait and initially retreated to safety in the bow of the ship while the shark thrashed about, damaging equipment and fuel lines. To keep the shark alive while a rescue ship towed the research vessel to shore, the crew poured water over its gills and eventually used a pump for mechanical ventilation. The shark was ultimately lifted back into the water by crane and, after becoming disoriented and beaching itself in the harbor, was successfully towed out to sea, swimming away. The incident was judged to be an accident.