Shark Attacks Doubled on Some Coastlines, but Scientists Say Don't Worry

It's our fault, not theirs. 

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In 2015, an unprecedented 16 shark attacks on humans occurred in North and South Carolina, causing panic among frantic beachgoers. To some scientists, it was perplexing too: Was there something strange happening in the water, or was the uptick in attacks normal, statistically speaking? The results of a study published Wednesday in PLOS One clear up the confusion. They are at least somewhat comforting.

The study was led by Stephen Midway, Ph.D., a Louisiana State University fish ecologist whose interest was piqued by the Carolinas shark scare in 2015.

“I was curious what the likelihood of shark attacks is in a certain number of years at different places around the world,” he said. “While shark attacks are often reported in numbers, we factored in the regional human populations to determine the rate of shark attacks worldwide.”

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Shark attacks are becoming more common in the areas where population has increased. 

And so, he and his colleagues, including University of Florida director emeritus and global shark expert George Burgess, Ph.D., turned to the grisly data in the International Shark Attack File, a database maintained by the Florida Museum of National History. The file contains data on every shark attack that’s happened internationally since 1960.

By comparing global and regional data from each year, the team confirmed that shark attack rates have doubled over the past 20 years in highly populated areas, like Southern Australia, the US’s East Coast, and South Africa. But rather than frame this discovery as a reason for concern, they show that it can help us understand why more shark attacks are happening in the first place.

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Beaches like this one in South Carolina are getting more shark attacks — but they're also hosting a lot more humans.

To the average beach-goer, an uptick in shark attacks may, understandably, spark fears that the local sharks are becoming especially violent or ravenous. But what makes Midway’s research so important is that it attempts to redirect our concerns from the sharks to the environment in which they live. By pointing out all the global hotspots for shark attacks, the data allows us to see what factors those areas have in common.

The most important factor appears to be the size of the human population in those hotspots.

“As development increases along the coast and in beach communities, more residents and tourists frequent these waters,” Midway said. “With more people in the water, the chance for a shark attack increases.”

This is not super comforting, but it makes sense. It’s not that the sharks are especially hostile; they’re just behaving like normal sharks and biting at organisms that look like food. If there are more organisms in the area — visitors to an increasingly popular beach — it makes sense that there will also be more biting.

Sharks Are Just Being Sharks

This is useful, albeit troubling, information for anyone who plans to travel to a crowded shoreline. “The number of shark attacks in any given year or region is highly influenced by the number of people entering the water,” note the keepers of the International Shark Attack File.

Despite their findings, the team wants to make clear that, regardless of population and other local factors like temperature and weather, shark attacks are not something we should be worried about. “Despite the cultural perception of shark attack risk, the risk at larger scales is not very high, and where it is increasing the rates are low and preventative measures are more likely to take place,” they write.

This study is a good reminder that shark attacks occur when humans invade the sharks’ space, not because sharks are particularly hostile toward humans. If they were, though, you probably couldn’t blame them: We’re not only responsible for the destruction of their habitat but also for harvesting them — sometimes, as scientists reported earlier this year, to fry up in fish and chip shops.

“That sea doesn’t owe us the right of 100 percent safety — we’re visitors to it, we’re eco-tourists,” Burgess told Inverse in a previous interview about the shark attacks that inspired the pervasive modern fear.

Both Midway and Burgess hope the information from this study can inform how people protect themselves from shark attacks, as well as protect the sharks from undue demonization.

“The thought that there’s something out there that we don’t control, I suspect, is offensive to the psyche of a lot of people,” said Burgess previously, “and unfortunately as a result of that, we still see in some quarters, people that will argue that sharks serve no purpose, and that if a shark attack occurs, we should be out there killing them.”

Abstract:

Shark attacks are a global phenomenon that attracts widespread attention and publicity, often with negative outcomes for shark populations. Despite the widespread perceptions of shark attacks, trends in human water activities and shark populations are both dynamic, resulting in variable rates of shark attacks over space and time. Understanding variable trends in shark attacks may contribute to a better understanding of risk, and a more tempered response in the wake of an attack. We found that global shark attack rates are low, yet variable across global regions and over decades. Countries with low populations were found to have the highest rates of attack, while countries with high populations (U.S.A., Australia, South Africa) tended to have overall low attack rates, but also much more interannual variability. From the 1960s to the present, those countries with the highest populations also tended to be the places where attack rates have increased. Ultimately, shark attack risk is also driven by local conditions (e.g., time of day, species present); however, a global scale understanding of attack rates helps place risk into perspective and may contribute to a more scientifically-grounded discussion of sharks, and their management and conservation.