Shark attack

A shark attack is an incident in which a shark bites or otherwise injures a human. Every year, around 80 unprovoked attacks are reported worldwide. Despite their rarity, many people fear shark attacks after occasional serial attacks, such as the Jersey Shore shark attacks of 1916, and horror fiction and films such as the Jaws series. Out of more than 500 shark species, only three are responsible for a double-digit number of fatal, unprovoked attacks on humans: the great white, tiger, and bull. Humans are not part of a shark's normal diet. Sharks usually feed on small fish and invertebrates, seals, sea lions, and other marine mammals. A shark attack will usually occur if the shark feels curious or confused.

Terminology While the term "shark attack" is in common use for instances of humans being wounded by sharks, it has been suggested that this is based largely on the assumption that large predatory sharks (such as great white, bull, and tiger sharks) seek humans as prey. A 2013 review recommends that only in instances where a shark clearly predates on a human should the bite incident be termed an "attack," implying predation. Otherwise, it is more accurate to class bite incidents as "fatal bite incidents". Sightings do include physical interaction, encounters including physical interaction with harm, shark bites include major shark bite incidents, including those that require medical attention, and fatal shark bite incidents that result in death. The study suggests that only where an expert validates the predatory intent of a shark would it be appropriate to term a bite incident an attack.

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. Rather, these incidents are considered 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 attack Provoked attacks occur when a human touches, hooks, nets, or otherwise aggravates the animal. Incidents that occur outside of 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 attack 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 trying 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 via crane and, after becoming disoriented and beaching itself in the harbor, was successfully towed out to sea. The incident was judged an accident.

Reasons for attacks Large shark species are apex predators in their environment, and thus have little fear of any creature (other than orcas) with which they cross paths. Like most sophisticated hunters, they are curious when they encounter something unusual in their territories. Lacking any limbs with sensitive digits such as hands or feet, the only way they can explore an object or organism is to bite it. These bites are known as test bites. Generally, shark bites are exploratory, and the animal will swim away after one bite. For example, exploratory bites on surfers are thought to be caused by the shark mistaking the surfer and surfboard for the shape of prey. Nonetheless, a single bite can grievously injure a human if the animal involved is a powerful predator such as a great white or tiger shark. A shark will normally make one swift attack and then retreat to wait for the victim to die or weaken from shock and blood loss, before returning to feed. This protects the shark from injury from a wounded and aggressive target; it also allows humans time to get out of the water and survive. Shark attacks may also occur due to territorial reasons or as dominance over another shark species. Sharks are equipped with sensory organs called the Ampullae of Lorenzini that detect the electricity generated by muscle movement. The shark's electrical receptors, which pick up movement, detect signals like those emitted from wounded fish. For example, someone who is spearfishing, leading the shark to attack the person by mistake. According to George H. Burgess, director of the International Shark Attack File, "Attacks are basically an odds game based on how many hours you are in the water".

Statistics

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