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Record number of worldwide shark attacks in 2015 linked to 'double whammy' of climate change, El Nino

Worldwide shark attacks reached an all-time record high in 2015, according to the International Shark Attack File (ISAF).

In a recently released study, the organization reported that there were 98 cases of unprovoked shark attacks on humans around the world. The previous record was 88 set back in 2000. There were 59 attacks reported in United States waters, which is the most of any nation in the world, and 30 of those occurred in Florida.

Australia, with a total of 18 attacks, and South Africa, with a total of eight attacks, accounted for the second- and third-highest number of unprovoked incidents.

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The ISAF, which is a part of in the Florida Museum of Natural History at the University of Florida, cited the growing human population and resulting increase in human activity in the world's oceans as one of the reasons for the record total of incidents.

"As world population continues its upsurge and interest in aquatic recreation concurrently rises, we realistically should expect increases in the number of shark attacks and other aquatic recreation-related injuries," the report stated.

"In theory, we should see a record number of shark attacks every year, because a shark attack is fundamentally an odd situation that's built on the number of humans in the water and the number of sharks in the water," George Burgess, curator of the ISAF and director of the Florida Program for Shark Research, said.

"We frankly are swamping sharks out of their own environment [because] we're putting so many people in water in nearshore areas where the sharks often are very common," he said.

While the human population continues to grow, concern remains for the overall amount of sharks in the oceans.

Although Burgess wrote last summer that the great white shark population is on the rise, other shark populations are declining or holding at a greatly reduced number in many areas of the world due to overfishing and habitat loss, according to the ISAF.

Despite the record number of incidents, the ISAF reported that only six fatalities occurred in 2015, which is right around the annual average from the previous decade. The only death reported in the U.S. occurred in Hawaii.

Advances in beach safety practices, medical treatment and an increase in public awareness are several of the factors that have lead to a constant reduction of fatality rates over the last 11-plus decades, the ISAF said.

Warmer ocean waters were also a factor in the record tally. Burgess said the continued effects of global climate change, plus the presence of a strong El Niño acted as a "double whammy" and the net results have contributed to the increase in attacks.

"Since most sharks are warm-water species, they now are covering a wider area than they once did," Burgess explained. "And so in the summertime they head farther north or south depending on which hemisphere they are in."

The rise in ocean temperature was particularly notable after one shark attack was reported in New York, only the 10th recorded occurrence in the state's history.

"It's a very uncommon phenomenon to have sharks and humans getting together in New York waters, so the fact that we had one there is just a little hint that things are a little warmer than they [have] been," Burgess said.

The number of attacks each year is subject to a number of variables such as changes in meteorological and oceanographic conditions, as well as socioeconomic factors that influence whether or not people can afford to take vacations to the beach.

For instance, in 2014, there were only 72 attacks around the world and three fatalities. The 72 attacks were the least amount of incidents reported since 2009.

"Some years [the number is] a little higher or a little lower depending on how those factors go," Burgess said.

In order to even out year-to-year variability, the ISAF examines trends in shark attacks on a per decade basis.

Over the past 11 decades, each decade had more attacks than the last and that trend will continue into the future as long as humans continue their population growth, Burgess said.


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