As noted, the majority of serious and fatal shark bites and attacks on humans come from predatory (and apex) shark species like Tiger sharks, Great White sharks, and Bull sharks. Other, more common shark bite incidents are from species including Blacktip, Reef, Whitetip, Bronze Whaler, and Spinner sharks. Scientists offer a few explanations for why sharks attack humans, including the following:
MISTAKEN IDENTITY: Sharks have excellent eyesight and a keen sense of smell. Sometimes sharks may mistake a human for a seal, fish, or other prey, especially if the person is swimming in murky water.
ASSOCIATION OF HUMANS WITH FOOD: Sharks are highly intelligent, and when humans feed sharks over time, they may come to associate boats and/or humans in a certain area with food, which increases the likelihood of a shark attack. For this reason, you should not feed sharks or seek to lure them toward you or your vessel; for your safety, and everyone else’s too.
DEFENSE: Sharks may attack humans if they feel threatened or cornered. This can occur when a human accidentally comes between a shark and its prey, or if a shark is protecting its space. There is debate about whether sharks are territorial, and if so, which species and to what extent, but as a matter of common sense, areas where there are multiple shark sightings should be entered with caution. Wise safeguards include looking for caution flags posted by local authorities, speaking with lifeguards and beach patrol, and researching shark sightings in the area.
HUNGER: Sharks can be opportunistic feeders and may attack humans if they are hungry and cannot find their usual prey. This can happen in areas where sharks' natural prey is scarce, or when fishing or boating activity in the area has disrupted the food chain. This can also happen due to natural migration patterns. During late summer and fall, an estimated 25% of adult female Tiger sharks migrate to Hawaii, ioften causing a spike in shark attacks. Again, local knowledge is a key component to shark safety.
CURIOSITY: Sharks are naturally curious creatures and may investigate humans in their environment. Sometimes, this curiosity can escalate into a shark bite.
There are several reasons why sharks attack humans, and by understanding the shark’s motivation for approaching you, you can take measures to dissuade a shark from pursuing you as prey, mistaking you for food, and/or reducing elements of interest a curious shark may wish to investigate. Remember, an investigative shark bite is the most common type of shark “attack”. Sharks don’t have hands, so they use their mouth and teeth to probe.