Fewer sharks in oceans, why more shark attacks?

BEIJING, Feb. 28 (Xinhuanet) -- The number of sharks swimming the oceans has decreased, but the number of people swimming in the ocean has increased, leading to a rise in shark attacks, says and international shark expert.

George Burgess, curator of the International Shark Attack File at the Florida Museum of Natural History, said beach-goers don't just dip a toe in the water and retreat to their warm beach towel, they hang out in shallow water (home for many sharks) for long periods of time to surf, windsurf, boogie-board, kayak and scuba dive.

The number of worldwide shark attacks overall increased from 63 in 2006 to 71 in 2007, continuing a gradual upswing during the past four years, Burgess said. There have been five unprovoked shark attacks so far this year (most shark attacks are unprovoked).

"There are more people in the water than there ever have been," Burgess told LiveScience. "We can pretty much predict that next year there will be even more attacks. Even if shark populations are declining, which we know they are, even in a local situation if populations have been depleted, there is still a probability of getting an attack."

Julia Baum, a researcher at the Scripps Institute of Oceanography in San Diego, California, says sharks are disappearing from the world's oceans because of overfishing. Baum and some of her shark-tracking colleagues made comments to reporters earlier this month at the annual meeting of the American Association for the Advancement of Science in Boston.

Sharks killed one human in 2007, according to the International Shark Attack File, but humans killed an estimated 38 million sharks for their fins each year, Baum said. That's as many sharks as the entire human populations of the 35 largest cities in the United States. Other estimates are nearly double that.

The scale of the problem of disappearing sharks is global due to shark finning, the process of cutting off a shark's fins and throwing the rest of the animal overboard still alive, leaving it to die, Baum said.

Finning makes use of only 2 to 5 percent of the animal, but shark fins are now one of the most highly valued marine commodities. A bowl of shark fin soup can sell for 100 U.S. dollars, so there is high incentive for fishermen to fin.

"Sharks evolved 400 million years ago, and yet we could now lose some species in the next decade, so that would be just the blink of an eye in evolutionary time," Baum said.

Sharks are thought to be crucial to the entire marine ecosystem: they are top predators and help to keep smaller sharks and rays from devouring too many scallops, clams and other commercially important species of marine life.

(Agencies)