Nat Geo Sharkathon | 'When Sharks Attack': Sharks mistake humans for prey due to low visibility in murky water

Studies into shark attacks over the years suggest that the more people in the water, the more likely they are to encounter a shark. An attack though is often a case of mistaken identity


                            Nat Geo Sharkathon | 'When Sharks Attack': Sharks mistake humans for prey due to low visibility in murky water
(Getty images)
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Shark attacks are every surfer and beachgoers' worst nightmare. The US reports at least 16 shark attacks each year with one fatality every two years. Although historically, the death rate from shark attacks much higher than what it is today, easy access to emergency services and medical treatment has brought the numbers down. In reality, however, the number of shark attacks is only increasing each decade, mostly because of the surge in the number of bathers.

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But why exactly do people fall prey to shark attacks? National Geographic is providing us with answers to this question. As part of its annual 'Sharkfest', the network is focusing on the premise of shark attacks in the US in the documentary, 'When Sharks Attack'. 

Studies and investigations into shark attacks over the years suggest that the more people in the water, the more likely they are to encounter a shark. Most encounters with the ocean's predator often occur in nearshore waters, inshore of a sandbar, or in areas with steep drop-offs. This typically because their food source tends to also congregate in these areas.

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One of the main reasons that sharks attack humans can be attributed to mistaken identity due to low visibility, says marine biologist Stephen Kajiura from Florida Atlantic University in Boca Raton. Another contributing factor could be a harsh physical environment like a breaking surf or strong currents. A feeding shark in this habitat has to resort to making quick decisions and rapid movements in order to gather its food. 

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Take, for example, Florida's New Smyrna Beach, which is practically known as the "shark bite capital of the world". According to statistics, there have been 828 reported incidents at the beach since 1837. The murky waters of the beach are popular among surfers because it happens to be adjacent to the Ponce de Leon Inlet, where the Halifax River and Intracoastal Canal mesh with the Atlantic Ocean, around the shoulders of stone jetties.

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These very murky waters are also home to baitfish, which is basically shark aphrodisiac. In turn, this coincident location also brings sharks and surfers together and given a fateful encounter, the surfer's world above the waves collides with a shark's underneath.

(National Geographic)

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These attacks, however, would comprise one type of attack akin to a "hit and run", and usually occurs in the surf zone, where swimmers and surfers become common targets. In this case, the victim rarely sees the attacker and the shark does not return after it inflicts its accidental prey with a bite or slash wound. It is not surprising that sharks might occasionally confuse humans for their normal prey.

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The general overview is that they quickly realize that a human is a foreign object upon biting, seeing as it is larger than the usual baitfish that it preys on, and immediately releases the victim to not return. Injuries to victims in the "hit and run" attacks are relatively small lacerations, often below the knee, and are mostly not life-threatening.  

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According to a 2010 University of Florida study, shark attacks are most likely to occur on a Sunday, in less than six feet water, during a new moon and involve surfers wearing a black and white bathing suit. The two other types of shark encounters are classified as "bump and bite" and "sneak" attacks. Both of these are very unusual, but they result in greater injuries and most fatalities.

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In "bump and bite" attacks, sharks tend to circle their victim and bump into them before they strike whereas in "sneak" encounters they attack without any prior warning. While these attacks usually involve divers or swimmers treading in slightly deeper waters, they also occur in shallow waters near shore in some areas of the world. 

'When Sharks Attack' premieres on July 20 at 9/8c on National Geographic.

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