Sharks Think Some Humans Are Birds
Certain sharks appear to confuse some recreational water users with birds, suggests a detailed case report documenting a fatal shark attack on a teenager in the South Pacific.
The report, published in the Journal of Forensic and Legal Medicine, indicates that kitesurfers could be at particular risk for such confusion. The described victim was a 15-year-old kitesurfing male who died after a tiger shark attacked him in the South Pacific.
"We hypothesize that the shark may have confused the motion of the kitesurfer, who was pulled by his kite without the board, with a bird overtaking the water," lead author Eric Clua told Discovery News.
Clua, a marine biologist and veterinary surgeon based in French Polynesia, and co-authors Pierre-Marie Bescond and Dennis Reid studied the remains of the victim. When the shark attack occurred on May 21, 2011, the teenager was kitesurfing with a group of five in waters off the city of Koumac on the northwest coast of New Caledonia. The water was clear and warm, with a temperature of around 79 degrees Fahrenheit.
After kitesurfing for about 45 minutes, the young man lost his board, but was still holding his kite and being pulled along the surface. Suddenly he shouted that a shark had bitten him. Friends tried to help and perform CPR, but without success.
Examination of the body determined that the shark wrapped its entire mouth around the person's left leg, removing significant amounts of tissue. The shark inflicted a second bite with almost no loss of tissue. The location in the water, nature of the attack, and tooth impressions on the body revealed that the bites were made by a nearly 10-foot-long tiger shark.
The authors mentioned that "when a kitesurfer does lose his board and is pulled by his sail (kite) along the surface, such as in the present case, with relatively high speed and intermittent touching down on the surface, it could represent a strong feeding stimulus for a shark."
Sharks in waters off of Florida, Papua New Guinea and Western Australia also have attacked kitesurfers. Surfers still suffer more shark attacks and fatalities, but kitesurfing is growing in popularity, so more attacks on individuals engaged in this sport are expected.
Tiger sharks and certain other sharks are known to feast on birds, as well as sea snakes, fish, turtles, marine mammals and more.
If the shark is a juvenile, it might learn to prey upon humans, such that individual sharks could attack multiple people during their lifetimes.
A sand tiger shark in the Australia, Gold Coast.Getty Images
Clua explained, "Sharks, as a main difference with marine mammals that learn from their older conspecifics, have to learn by themselves...So (attacking a human) might be a mistake at the beginning and then (later become) a more 'normal process' for a given shark to prey on a human being."
He added that attacking humans "is a problem of individual behavior of some sharks, not of a given species and even less for sharks in general."
Austin Gallagher, a researcher at the University of Miami's Abess Center for Ecosystem Science and Policy, told Discovery News, "Tiger sharks are primarily visual predators, which forage on air-breathing animals, so this was probably an investigatory situation."
Both he and Clua are against culling sharks to prevent attacks on humans. They both warn that the ocean and its marine life present inherent risks.
"The sea is not a zoo where you go to see dangerous animals without any chance of being wounded," Clua said. "If you go to sea, you must accept the rules and risks, like an alpinist accepts the risk of falling from the mountain. Why should we cut the mountain if he falls and dies?"