Scientists have not yet conclusively identified the species of shark responsible for a fatal attack on a kite surfer off a Stuart, Fla., beach, but they have ruled out any involvement by a great white shark.
Some media reports speculated that a group of white sharks might have attacked the kiteboarder on Wednesday. Florida-based shark experts say the reports were based on an apparent misquote and media hype.
“Our investigation definitively indicates it was not a great white shark,” George Burgess, director of shark research at the Florida Museum of Natural History, said on Friday.
Instead, he said, an examination of the victim’s wounds suggests that the attacking shark was eight to nine feet long and was more than likely a bull shark or tiger shark.
He said that although the lifeguard who attempted to rescue the kiteboarder saw several sharks nearby, only one shark bit the man. According to officials, there was a very deep and fatal bite to his thigh, a second bite to his buttocks, and a defensive wound to his hand.
Most shark attacks are hit-and-run
Most Florida shark bites are quick nips, like a hit-and-run, experts say. This attack was different.
“The attacking shark really meant business. This was not likely to be a mistaken-identity situation,” Mr. Burgess said. “This was a shark that was attacking with some real meaning.”
Although Burgess was able to narrow the range of potential species involved in the attack, officials have made arrangements to consult a second shark-bite expert to help solve the mystery.
Grant Gilbert, a research scientist in Vero Beach, says he will meet on Monday with the Martin County medical examiner to try to match the victim’s wounds with an extensive inventory of shark jaws. It is a kind of forensic shark-bite version of "CSI."
“Sharks can be identified by their dentition [teeth],” he says.
A tiger shark has saw-edged teeth on both its upper and lower jaws. In contrast, a bull shark has pointed teeth on its lower jaw and triangular, serrated teeth on the upper jaw.
The pointed teeth are designed to hold prey, while the upper teeth are built for cutting. According to Gilbert, puncture wounds produced by the lower jaw would be present in a bite from a bull shark, but not from a tiger shark.
Forensic evidence focuses on bite marks
But that may not end the inquiry, he says. Two other sharks, the dusky shark and the silky shark, share similar jaw configurations with the bull shark. At that point, Gilbert says, the sharks may be differentiated by the number of teeth in the upper and lower jaws. Much depends on the evidence from the bites, he says.
In 1998, a 9-year-old boy was killed by a shark near Vero Beach. Gilbert worked on that case as well. The two main suspects, he said, were a bull shark and a tiger shark.
The bite characteristics allowed officials to rule out the bull shark. They concluded the attack was caused by a tiger shark.
Tiger sharks prey on sea turtles, and their jaws are evolved to the task, Gilbert said. “It was a young tiger shark, and it thought it had a sea turtle,” he said, of the Vero Beach attack 12 years ago.
Migrating sharks not probably involved
Televised reports about the Stuart shark attack have included stock footage of sharks migrating up Florida’s east coast, Gilbert says. But those migrating sharks, the research scientist says, are probably too small and unlikely to be involved in an attack like the one Wednesday.
Gilbert says he suspects that the kite surfer plunged into the water at exactly the worst place. “It is possible that he actually fell on the shark,” he said. “If there were a number of sharks out there, it could be that he just fell at the wrong spot at the wrong time.” The researcher added, “We’ll never know.”
There have only been 28 recorded shark bites in Martin County since 1882, says Mark Perry, director of the Florida Oceanographic Society in Stuart. This week’s attack was the first fatality in the county.
The victim, Stephen Schafer, was well known in Stuart, said Mr. Perry, whose office is across the street from Stuart Beach, where the attack took place.
A memorial ceremony is set for Saturday at Stuart Beach, where Mr. Schafer’s friends will hold a barbecue and a “paddle out,” in which surfers paddle offshore and form a large circle in remembrance.
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