Sharks, Humans Living So Close; Why Not More Attacks?
Despite myths perpetuated by the thriller 'Jaws,' now marking its 40th anniversary, humans remain an un-tasty, unnatural meal for sharks.
The movie thriller "Jaws," with lines such as "a tiger shark's like a garbage can, it'll eat anything," did a lot to perpetuate myths about sharks, even though the reality is that humans taste awful to sharks and the chance of being attacked by one of these apex predators is 1 in 3,748,067.
As "Jaws" celebrates its 40th anniversary this month, shark experts explain that basic math, shark biology, improved shark detection methods, and other factors are why there are not many shark attacks worldwide. Attacks remain relatively low despite the fact that more and more people are heading out into the water and into shark territories.
"The human population continues to grow, with more people than ever before engaging in recreational water sports like surfing, body boarding and scuba diving," George Burgess, director of the International Shark Attack File at the Florida Museum of Natural History, told Discovery News.
A few shark species, such as great whites, are also increasing in number.
Burgess, as well as Ryan Orgera of Monmouth University's Urban Coast Institute, noted that great white shark populations are on the rebound, with numbers increasing in waters off of the northeastern United States and California.
"Shark attacks, however, are down as a whole, with 72 unprovoked attacks occurring last year and three fatalities," Burgess said, adding that "75 attacks were recorded in 2013."
There are still some shark attack "hot spots" at present, such as off the coast of Maui, but even there, a reality check is needed. While headlines may say that "attacks in Hawaii have tripled" compared to eight years ago, the numbers for both periods are still in the single digits (seven in 2014, two in 2007).
Burgess said basic math holds that sharks+humans=attacks, given that sharks are exploratory predators, but because our population growth far exceeds that of slow-to-reproduce sharks, the attacks may only increase by tiny increments over the decades.
Mahmood Shivji, director of the Guy Harvey Research Institute at Nova Southeastern University, agrees. He told Discovery News that despite the good news about great whites recovering in some locations, overall, "there are just fewer large sharks around, given their well-documented population declines from overfishing."
We've also become cleverer at steering clear of sharks. Burgess' son, for example, is an expert on using drones to track animals, as these devices can relay information in an instant without much noise and visual disturbance.
The drones, however, can also pick up scantily clad swimmers and goodness knows what else, so "restrictions on the usage of drones are only going to get tighter," Burgess said. "Due to privacy concerns, I don't see them as having much promising broad application use in future to detect sharks."
Divers can also now wear personal safety devices, basically electrodes, to ward off sharks, he said. Similar gadgets can be placed on surfboards. These again are not perfect solutions, though, he said, due to cost, awkwardness and other factors.
Burgess added, "You still can't beat a lifeguard with binoculars and a good pair of eyes in terms of effectively spotting sharks."
Even if a shark is present, there is a high chance that it will not attack humans. As Shivji said, "it's extremely uncommon for sharks -- even when around -- to bite people, even when there are more people in the water."
In the report "Global Perspectives on the Biology and Life History of the White Shark," Neil Hammerschlag of the University of Miami and colleagues explained that white shark teeth, and possibly that of other species, are "innervated." They "propose that teeth and gums are important sensory structures for this species."
Some of Hammerschlag's colleagues further proposed that sharks can sense the calorie and nutrient-rich blubber of marine mammals, with the bony and muscular bodies of humans not being very appealing to them. Some of that probably has to do with habit. Just as humans may get used to eating chicken as opposed to some other bird, so too do sharks learn to target fish, squid, other sharks and marine mammals like sea lions, seals and small whales.
Yet another reason for the low number of shark attacks is that sharks are often on the move.
Shivji explained, "Many of the larger sharks seasonally migrate -- some short distances, some massive distances -- and so at some times of the year there are fewer sharks in a place than at other times."
While many mysteries remain about shark migrations and other shark behaviors, clearly we know more about these toothy predators than we did 40 years ago, when "Jaws" debuted.
"'Jaws' was done so well that many people took this piece of fiction as nonfiction," Burgess said. "Enjoy the movie for what it is, a great thriller, but take time to learn the facts."
Great white shark at Ripley's Aquarium of Canada.