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Beyond Surfing’s “Bro-Science”: Looking for Answers to Hawaii’s Shark Attack Spike

After Hawaii saw four shark attacks in as many weeks last month, a North Shore surfer wonders how safe it is to share the ocean with another apex predator.
Courtesy Matthew Catalano

At Leftovers Beach, a popular surf spot on Oahu's North Shore, you can paddle out 150 yards and still not reach depths over 10 feet. That's about where Colin Cook was sitting on his board on the morning of October 9, when the tiger shark pulled him under.

Most attacks on humans end after the initial strike, once the shark realizes its prey is not a fish, but this shark continued to go after Cook. He fought fought back, beating it with his hands and kicking at it, but only when a nearby stand-up paddler, Keoni Bowthorpe, came to the rescue did Cook have a chance to escape. Bowthorpe used his paddle to fend off the shark and helped the injured Cook roll onto his back. The shark continued to trail the men as they struggled toward the rocky shore.

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Bystanders on the beach improvised a surf-leash tourniquet and first responders arrived shortly thereafter, but it wasn't enough to save Cook's left leg, which had to be amputated just above the knee. Bowthorpe was unhurt but deeply affected.

"Personally, I have taken this experience as an opportunity to remember to be humble," he said. "As water people, I think surfers sometimes have a clearer view of our place with Mother Nature—her power, what she is capable of."

Eight days later, on October 17, a shark attacked 44-year-old man swimming between the Mokulua Islands, on the east side of Oahu. The shark is believed to have been a large tiger shark, and the swimmer, Tony Lee, ripped out the shark's eyeball in defense. Lee lost his right foot in the attack.

On October 29, my phone flashed with a news alert: an unknown species of shark had attacked a 10-year-old bodyboarder at Makaha Beach on Oahu's west side. Five days later, a shark attacked a snorkeler off the coast of Puna. It was the fourth attack in Hawaiian waters in as many weeks.

I've been surfing the North Shore for 18 years and have witnessed clusters of shark attacks in the past, most recently near Maui in 2013 and 2014. Every time it happens, the media storm engulfs the islands, and the question on everyone's mind—scientists, surfers, tourists—becomes whether we're seeing a trend. Is there a reason for the frequency of the attacks, or do we write them off to random chance?

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Photo courtesy Matthew Catalano

A guaranteed reaction to a cluster of shark attacks is plenty of "bro-science" and hearsay in the surf lineups. "They only eat at dawn and dusk." "Sharks prefer to hunt in calm water." "There's no fish left for the sharks to eat because of commercial fishing in Hawaiian waters." There's really no end to it. The pseudoscience gets particularly heavy after a series of attacks, and everyone in the water is edgy.

For more credible information, I reached out to University of Hawaii researcher Carl Meyer, who studies the relationship between shark ecotourism, like cage diving, and human-shark interactions. Meyer warns against grouping attacks as a cluster, because the individual incidents may be wholly unrelated.

"We need to understand that any single shark bite is a unique event resulting from a confluence of factors that bring a person and shark together," Meyer said. "This makes individual shark bites hard to decipher because we invariably know almost nothing about the particular shark involved in any given incident."

That said, certain factors may contribute to an overall increase in attacks at a given time.

"There are natural cycles in shark biology that may help to explain seasonal patterns of shark bites," Meyer said. "For example, in Hawaii we typically see more shark bites during the fall pupping season for tiger sharks."

In the fall, tiger sharks migrate from the northern Hawaiian islands to have their babies in the waters surrounding the southern islands, which see far more beachgoers. The confluence of migrating sharks and people in the water can lead to an uptick in attacks.

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We're also in an El Niño year, whose warmer air currents mean higher water temperatures near shore. The El Niño warming effect drives pelagic fish (i.e., shark prey) to seek cooler, nutrient-rich water away from shore. Sharks are left with less prey available in their natural hunting grounds.

"Clusters of shark bites also occur during non-El Niño years, for example in Maui in 2013 and 2014," Meyer said. "So it is not clear whether El Niño conditions are a factor in recent shark bites around Oahu."

Trends in human activity over recent decades may also play a role alongside sharks' natural behaviors or even, as in the case of climate change and El Niño, exacerbate their effects.

"There are more people now than ever spending more time in the ocean and participating in activities that take them further offshore, further into the shark's home, for longer amounts of time," said Ocean Ramsey, an aptly named shark biologist who runs One Ocean Diving, a shark research and diving program in Haleiwa, Hawaii.

Ramsey is quick to add that sharks kill very few people each year. Six people, on average, have died annually from shark attacks around the world since 2005, according the International Shark Attack File—though that number only reflects data from the "world locations with the highest shark activity." In U.S. waters, sharks have attacked an average of 41 people each year since 2001, and someone dies from a shark attack once every two years. We don't know the global shark population, Ramsey points out, but we do know that commercial fishing operations kill about 100 million of them each year.

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I asked her about Colin Cook's incident at Leftovers, adding that I learned a shark killed a bodyboarder there in 1992. Sharks are not naturally territorial hunters, she told me, but that doesn't mean they won't frequent an area if given good reason, such as a reliable food source. Fishing with the use of chum—ground-up fish parts—could be altering the animal's' natural behavior and migration patterns. Likewise, fish scraps from cleaned carcasses that get dumped in harbor waters could also encourage sharks to come closer to shore more often.

One Ocean Diving operates the Pelagic Animal Research and Interaction Program, which is essentially a survey of locally seen sharks to identify individuals and record their behavior and movements. Among the parameters measured when sharks are spotted are the date, time, weather, the sharks' depth in the water, its distance from shore, and its gender. The data is collected in the Shark Sighting Database, maintained by the Shark Trust. The goal of assembling the information is to have a better idea of where sharks are and what they're doing.

"I continue to collect behavioral data that will and is being used to help reduce adverse interactions," Ramsey said. "It is wonderful to now have the program open to the public so they can come learn about sharks from a scientific and behavioral perspective.

"Keoni Bowthorpe [who rescued Cook at Leftovers] has been out with me on a shark survey several times and told me that it gave him the extra courage to go over and help Colin out, considering his level of experience having already spent time in close proximity to large sharks."

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Photo courtesy Matthew Catalano

Despite how little we seem to truly know about what might drive spikes in shark attacks, when they do happen, it generates pressure for local authorities to respond. After Lee's encounter with a shark in the Mokulua Islands, state officials considered closing two nearby beaches. Lifeguards posted warning signs and patrolled the water on jet skis, though the beaches remained open. In the past, however, the response has been more drastic. And far bloodier.

From 1959 to 1976, the Hawaii Institute for Marine Biology and the state's Department of Land and Natural Resources culled about 4,500 sharks from Hawaiian waters in an effort to reduce attacks. It didn't work, though—the number of attacks went unchanged. When sharks killed two bodyboarders in Hawaii in 1992, authorities reignited the debate over whether to cull. A Maui lawmaker even introduced a bill for a state-sponsored kill, though it was never enacted.

Ramsey denounces this tactic as worse than ineffective. Sharks can travel up to 200 miles in a day, she says, and therefore targeting them with acute treatments—like hunting sharks in the vicinity of a certain beach, along the North Shore, or even in Hawaiian waters—isn't likely to reduce their interactions with humans.

"The reality is that we depend on sharks for the air that we breath, as they are part of a complex marine ecosystem and their removal from areas has been scientifically proven to have damaging effects on fisheries, coral systems, and even local seafood abundance and correlating economies," she said. "Reality check: sharks have more to fear from us than we do from them."

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Ramsey and Bowthorpe have both worked on a documentary, called Saving Jaws, to stymie what they see as the species' otherwise inevitable extinction. The film follows the team of biologists as they freedive with sharks and advocate for stricter legislation protecting the animals, an end to "finning" the animals for shark fin soup, and to change public perception of sharks.

"Sharks have been apex predators since before the dinosaurs, before trees," Bowthorpe said. "To honor the ocean and its inhabitants by doing my homework, and being more aware than I have been in the past, perhaps that's how we demonstrate our respect for the ocean we all love so much. We show our reverence in our consistent effort to learn, train, and survive."

Even victims of shark attacks realize the importance of the animal's continued existence in the oceans we share. Ten years ago, Mike Coots lost his leg in a shark attack. Today, he surfs with a prosthetic leg, and on the morning of October 9, he was paddled out at Chuns Reef, close to Leftovers . When he heard about Cook incident, he rushed to the area.

"It was such a surreal feeling," he said. "I got to thank and hug the guy who saved his life."

Coots is now an outspoken advocate of sharks and particularly opposed to finning.

"Our oceans mean everything to me and if I can use the attack as leverage to speak to politicians about shark finning legislation, then why not," he said. "I have no animosity toward sharks, and feel like I was in the wrong place at the wrong time. I would hate for one day the youth of the world can only see sharks in a textbook, and at the rate they are being killed, that could become a reality.

Photo courtesy Matthew Catalano