All of a sudden it’s been two months since the last shark attack, a modest break from a two-year period in which Hawaii averaged a remarkable one shark attack per month.
Is it safe to go back in the water?
Kim Holland, one of Hawaii’s top shark researchers, thinks so. In fact, he’s predicting the number of shark attacks will diminish to previous levels of about three to four per year.
Holland, a professor with the University of Hawaii’s Hawaii Institute of Marine Biology, makes the prediction not because of anything he sees that will cause sharks to back off. Instead, it comes from the knowledge there’s really no apparent reason for the spike in the first place.
"I might be setting myself up for a fall if I look wrong, but that’s what I believe in the long view," he said. "Even if there was an attack today, you would still see fewer shark attacks over time."
Holland is one of the principal researchers in the two-year, $186,000 study to track the movements and behavior of Hawaii’s tiger sharks — the species believed most responsible for Hawaii’s shark bites. The study was commissioned by the state Department of Land and Natural Resources in August following one stretch in which there were four attacks in three weeks, including one fatality off Maui.
The last shark attack was Dec. 11, when a 29-year-old Captain Cook bodyboarder was left with cuts to the knee and hand from the bite of a 10- to 12-foot tiger shark off Naalehu, Hawaii island.
Shark attacks surged in 2012 with 10 incidents, an unprecedented number at the time. Then last year there were a whopping 14 attacks, including two fatalities. Compare that with the three-year span between 2009 and 2011, when there were only three per year, and to 2008, when there was just one shark attack.
Historically, Hawaii averaged between two and three shark attacks a year in the 1980s. During the past two decades, the annual average edged up to between three and four shark attacks.
Holland, who has studied sharks for decades in Hawaii, said he and his colleagues are unaware of any influencing factor that experienced a similar rate of change to explain the spike of 24 shark attacks over two years.
One popular notion is that the attacks are due to the fact more people than ever are swimming in Hawaii’s nearshore waters. But Holland contends that while it’s true resident and visitor populations have risen over the decades, there was no equally dramatic population spike during or preceeding the incidents in 2012 and 2013.
Another common theory links the shark attacks with the recovery of the sea turtle population. The argument goes that because tiger sharks eat sea turtles and an increasing number of turtles are found in Hawaii’s nearshore region, then the tigers are coming inshore with more opportunities to mistakenly bite surfers and swimmers.
Again, it does not add up, Holland said, because while turtles have swelled in number significantly over the last 20 years, there was no sudden spike in 2012 and 2013. Not only that, turtles are only one part of a varied diet of tiger sharks, he said.
Holland, who has caught and tagged hundreds of sharks, said scientists can’t point to any increase in shark numbers, nor have they seen a dramatic change in water temperature or any other obvious environmental factors that would cause a jump in shark incidents.
"There is no natural or man-made reason in the environment for this — no obvious reason for an increase in attacks," he said.
Which makes the uptick over the last two years not the new normal, but an aberration and anomaly, he said.
Holland’s assertions make sense to Yannis Papastamatiou, a former UH shark researcher who now works at the University of St Andrews in Scotland.
"Shark attack numbers are so low that they are very hard to analyze statistically," said Papastamatiou, who co-authored a study last year that documented an annual fall influx of pregnant female tiger sharks to the main Hawaiian Islands, offering a possible explanation for the historic increase in shark attacks from October to December.
"The annual numbers can fluctuate greatly around the average," he said. "Some years there may be no attacks, and other years many more. Of course, the numbers may go up as the number of people in the water increase, but there is no obvious cause behind the spike in attacks."
In making his prediction, Holland conceded that he might be compared to a gambler with inside information simply playing the odds.
"It’s like when you toss a coin and you know the odds are 50-50," he said. "If it lands 12 heads in a row and if you (toss the coin) long enough, you know it will go back to 50-50."
Last week there were at least three shark sightings in Hawaii, including two along the shore at Waikiki. Scientists say such sightings are not surprising because tiger sharks are common around all the Hawaiian Islands and are found over all parts of the reef — from the deep outer slopes to shallow bays — although they seem less frequent in very shallow waters used by swimmers.
The odds of becoming shark bait are extremely slim. According to the DLNR, the chances of getting bitten by a shark in Hawaii waters are less than 1 in a million.
Compared with other parts of the world, Hawaii is blessed with a remarkably low level of shark attacks, Holland pointed out.
And Hawaii is not alone in spikes in shark activity. In recent years West Australia, Reunion Island, Egypt, Brazil and other locations have seen their own versions of increased shark attacks, many of them fatal. In many cases no change in environmental conditions or other possible factors could be identified.
So, is it safe to go in the water in Hawaii?
"Any time is a good time to be in the water," Holland said.
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