With the board in its mouth, the shark pulled Mighall underwater for a second time. Moments later she popped back up to the surface with her damaged board. The animal had bitten clean through the fibreglass and foam.

Mundy grabbed hold of his cousin, put her on his back and paddled frantically for the shore. Earlier that day Mighall had been practicing water rescues with another girl during training with her local Surf Life Saving association, repeatedly being carried into shore as the “victim”. Now she was doing it for real.

“The shark was circling us underwater,” says Mighall. “Then this wave came in and Syb just said, ‘We have got to catch this as it is going to save our lives.’ I was just tapping the water as I was terrified but he was really paddling and the wave carried us to shore. The shark came with us all the way up to the beach as there is a deep gutter running up to it. We could see its fin as it surfed in on the same wave.”

Luckily for Mighall, among the few people on the beach who witnessed what had happened that day were a doctor and a nurse. They gave her vital first aid while waiting for an ambulance to arrive.

More than 10 years later, she still carries deep scars on her leg that trace the outline of the shark’s mouth. Her right leg is noticeably weaker than her left – so much so that she has to lift it with her hands when she wants to kick-start the dirt bike she rides occasionally.

Mighall was one of roughly 83 people around the world to be attacked unprovoked by sharks in 2009. It is a figure that has remained around the same level over the past decade. The average number of unprovoked attacks between 2013-2017, for example, was 84. In 2022 there 57 unprovoked shark bites on humans and 32 provoked bites, according to the Florida Museum of Natural History’s International Shark Attack File. Nine of these attacks where fatal, with five considered to be unprovoked.

But recent research indicates that shark attacks in some parts of the world appear to be on the rise. The eastern US and southern Australia have seen shark attack rates almost double in the past 20 years, while Hawaii has also seen a sharp increase. But why?

“Shark bites are strongly correlated to the number of people and number of sharks in the water at the same time,” says Gavin Naylor, director of the Florida Program for Shark Research, which maintains the International Shark Attack File. “The more sharks and people there are in one place, the greater the chance of them bumping into each other.”

This seems like an obvious point, but when you look closer at where attacks are taking place there are some clues as to what might be going on. The large human populations along the southern coast of Australia and the eastern coast of the US mean large numbers of people enjoying the water. But southern Australia has also seen rising numbers of fur seals along its coastline, the favourite prey of great white sharks in the region.

Similarly, seal populations off Cape Cod on the coast of Massachusetts in the US have rebounded in recent years, largely thanks to protection by the US’s Marine Mammal Act introduced in 1972. This has led to increased numbers of great whites in the area too during the warm summer months as they look to feast on the seals that pull themselves out to bask on the beaches.

Sadly, last autumn, Massachusetts suffered its first fatal shark attack in 82 years and growing numbers of shark sightings have led to a string of beach closures.

But there is no real evidence that sharks are actively hunting humans, according to the scientists who study them. Great whites in the North Atlantic, for example, show seasonal movement patterns, migrating thousands of miles to warmer waters further south during the winter months. Some mature adults will venture out into the open ocean for months at a time, covering tens of thousands of miles and diving to depths of 1,000m (3,280ft) as they seek prey.

“We are like helpless little sausages floating around in the water,” says Naylor. But despite being potentially such an easy meal, sharks are really not that interested in hunting humans. “They generally just ignore people. I think if people knew how frequently they were in water with sharks, they would probably be surprised.”

However, Naylor believes that the official statistics on shark attacks are probably an underestimate. Most reports come from highly developed countries with large populations and highly active news media. Attacks on remote islands or in less developed communities probably go unreported.

Looking deeper at the statistics for the number of shark attacks can reveal some fascinating trends. In 2018, there were just 66 confirmed, unprovoked attacks, roughly a 20% fall compared to previous years. Just four of these were fatal according to the International Shark Attack File, although another database of shark attacks records seven deaths. 

The reason for the fall in attacks – which bucks the overall trend of growing numbers of attacks – has been attributed to a sharp decline in the number of black-tipped sharks. These sharks account for many of the bites around the south-eastern US, migrating down the coast of Florida due to rising sea temperatures that have led their prey to become more dispersed.

For decades Florida has seen the most number of shark bites globally. The 16 cases it saw in 2022 represented 39% of the US total and 28% of all unprovoked bites worldwide. 

The findings highlight one of the key challenges in understanding why sharks bite humans. There are dozens of different species responsible for bites, each with their own unique behaviour, hunting strategies, prey and preferred habitat – although in many cases the species can be misidentified or not identified at all.

The majority of unprovoked attacks on humans where a species is identified involve three large culprits: the great white, tiger and bull sharks. Yet great whites – the species depicted in the film Jaws and demonised by Hollywood ever since – isn’t just a separate species, but an entirely different taxonomic order from the other two.

“There are 530 different species of shark and there is so much diversity among them. You can’t just group them together,” says Blake Chapman, a marine biologist who has studied shark sensory systems and recently wrote a book on shark attacks on humans. “Different species have such a range in terms of their sensory biology, how they behave, their motivations and the habitats they live in.”

Bull sharks, for example, tend to hunt in shallow, murky water that will require them to rely less on vision and more upon their sense of smell and electroreception, which allows them to detect minute electrical fields produced by their prey.

“(Great) white sharks, which often hunt in very clear water use their vision a lot more and their eyesight is much better,” says Chapman. There is also some evidence that shark teeth may also function as mechanosensory structures – similar to touch – to help the animals learn more about what they are biting.

Chapman believes there may be a complex set of reasons for why unprovoked attacks on humans appear to have risen in recent decades.

Aside from rising human populations along coastlines, the destruction of habitat, changing water quality, climate change and shifts in prey distribution are leading sharks to gather in greater numbers at certain hotspots around the world.

In 1992, for example, there was a sudden spate of shark bites off the coast of Recife, Brazil – an area that had no unprovoked attacks for the entire previous decade. Chapman believes that heavy commercial port construction in the area damaged large areas of reef and mangrove, potentially displacing species like bull sharks, which moved to new areas like Recife in search of prey.

Réunion Island in the Indian Ocean – renowned for its beautiful, unspoiled marine habitats – has seen a dramatic rise in tourism but in recent years it has also suffered a growing number of shark attacks by the bull and tiger sharks that live in the surrounding waters. Since 2011, there have been 11 fatal attacks on Reunion, mainly on surfers. Those who survive often lose limbs. Researchers have found that around two-thirds of the Reunion attacks have occurred in turbid water and swells of more than two metres – the favoured environment for bull sharks, which are thought to be responsible for most of the attacks.

Naylor believes that in most cases, sharks bites are a case of mistaken identity.

“If these animals are chasing bait fish, the flash of the white sole of a foot from someone kicking on a board might cause them to dart at it,” he says. “When you have a large animal like a tiger or a white shark, which move quickly, a bite is far more likely to be fatal.”

Great whites typically attack from below, delivering a massive catastrophic bite. In some cases they will withdraw while their prey bleeds to death before returning to eat.

“A great white in full predatory mode is quite a sight,” says Greg Skomal, a marine biologist with the Massachusetts Division of Marine Fisheries who has been tagging and tracking great white sharks since 2009. He should know – last year, as he was leaning over the pulpit on the bow of a research vessel while trying to tag a shark, a large great white breached directly underneath him with its jaws agape.

“It gave me some idea of what a seal feels like,” he says. “I’ve seen that behaviour a couple of times over the years we have been doing this. Most of the time we put a camera in the water and the sharks are completely complacent. We must have done it thousands of times. But on a handful of occasions they attack straight away, breaking the pole and the camera. It is like they are in a heightened predatory state where their senses lock onto any kind of stimuli.

“I wonder if those strikes on people that are not merely investigative are the result of a person being in the wrong place at the wrong time with a shark in this kind of heightened state.”

But for every attack on a person, there are just as many stories of people who have managed to get up close to these giant predators without any harm. Take Ocean Ramsey for example, who swam alongside an enormous 20-feet-long great white off the coast of Hawaii and made headlines around the world.

Skomal and his colleagues are now using new high-resolution tags that can give the researchers minute by minute and second by second data on what the sharks are doing.

He hopes it might help to answer questions about the behaviour of these animals as well as about where and how they breed. It could, ultimately, also help to tell us something about the reasons underlying attacks on humans, he says.

Some researchers are turning to forensic methods to try and unravel some of the reasons behind attacks. They are developing techniques to use DNA and bite-mark patterns to identify species, while others are examining video footage of attacks and comparing these to injuries to get a better understanding of what happened.

Data from shark spotters in South Africa have shown that great whites are more active near the surface, and so more likely to be seen, when water temperatures are above 14C, during a new moon and in the afternoon. Other research, however, has suggested that great whites are more successful hunters at night when there is a full moon.

Other researchers have suggested juvenile great whites may attack humans as they hone their predatory skills, in much the same way that young lions will experiment with whatever prey they can take on.

But regardless of the reasons for attacks on humans, the risks involved are still vanishingly small. In Australia the rate of shark attacks is in the order of 0.5 attacks per million people, while in the US it is less than 0.2 attacks per million. It is worth noting that in 2018, the US figures dropped to around 0.08 attacks per million while in Australia they rose to 0.8 attacks per million people.

These figures are blunt instruments, of course. They fail to account for the comparatively fewer numbers of people who actually use the water, and the fewer still who swim in water inhabited by dangerous sharks. But these statistics, however ridiculous or comforting they might seem, do little to dampen our fear of sharks.

“Fear has played a very important role in our evolution,” adds Chapman. “Humans don’t need to be eaten themselves by a sabre tooth tiger to learn to fear them. We learn that fear very quickly from a single story. People who have never seen a shark before fear them because we hear or watch stories about them.”

The focus on the risks that sharks pose to us also diverts attention from the far greater threat we pose to their survival due to over fishing and human-induced climate change. Some estimates suggest shark numbers in Australian waters, for example, have declined by between 75-92%.

But for those who are afraid and want to know how to protect themselves from a shark, some advise punching a biting shark in the gills or poking it in the eyes. Swimming in groups and staying close to the shore are known to reduce the risk of attacks. Wearing dark clothing and avoiding wearing jewellery can also help to reduce the chance of attracting a shark’s attention in the first place.

There are also a number of shark deterrents on the market that use electrical or electromagnetic pulses to interfere with the animals’ senses, but these have mixed results, according to research. (Read more about whether technology could reduce shark attacks).

In some areas, the local authorities themselves have taken action. Traditionally, some authorities have used shark nets to protect areas used by swimmers, but these are controversial due to the harm they do to other wildlife.

Instead, smart drum lines – which use baited hooks attached to a system that sends out an alert when triggered – are now being trialled at several beach locations along the coast of western Australia. When a shark takes the bait, an alert is sent to response teams who catch, tag and then release the shark in a safer location.

Another approach being tested in Cape Town, South Africa, is an electromagnetic cable that aims to discourage sharks from approaching areas used by swimmers. Scientists have also been testing an electromagnetic barrier as an alternative to shark nets.

These could be important steps as the harm caused by shark attacks can extend far beyond their immediate victims.

“Shark attacks cause a lot of personal loss, but the impact they can have on the wider community is often not considered,” says Dave Pearson, one of the founders of Bite Club, which offers support to the survivors of shark attacks. He himself was attacked by a bull shark while surfing eight years ago in south-west Australia, nearly losing his arm when the animal smashed into him, bit into his forearm to the bone and carried him underwater.

“After my attack, lots of my friends didn’t go back into the water for a long time,” he says. “The fear spreads really quickly.”

On a recent visit to Ballina, a surfing hotspot in New South Wales, Australia, Pearson saw just what a shark attack can do to a town. The area has suffered a spate of attacks, including two fatal ones on surfers in 2015.

“I was standing there watching these perfect waves coming in but there was not one person in the water,” he says. “One of the local coffee shops said they had suffered an 85% drop in business and the surf shop couldn’t give boards away. They were both thinking about closing.”