REGION — In the aftermath of a shark attack on a 13-year-old boy at Beacon’s Beach in Encinitas on Sept. 29, the public has been filled with horror and questions about how this could have happened and what can be done to prevent future attacks.
DNA evidence has confirmed that a white shark — proverbially referred to as a “great white shark” — was responsible for the attack that seriously injured Keane Hayes, who was diving for lobster early in the morning.
Geoff Shester, Ph.D., California campaign director and senior scientist at Oceana, said that most attacks by white sharks are cases of “mistaken identity.”
In conditions of poor visibility, such as low light or murky water, Shester said that a white shark can be unsure whether a person is a prey animal, like a seal or seal lion. The white shark then takes a bite to find out.
“It’s a massively powerful animal that can cause major damage or death with its bites, but it’s not intending to eat people,” Shester said. Humans do not have the blubber and high-energy fat that white sharks seek.
National Geographic expressed similar ideas in an article, noting that great whites, “who are naturally curious, are ‘sample biting’ then releasing their victims rather than preying on humans. It’s not a terribly comforting distinction, but it does indicate that humans are not actually on the great white’s menu.”
Risk factors in the ‘shark nursery’
Shester said that while the chance of getting bit by a shark is extremely unlikely, the higher-risk times are typically dawn and dusk when the water is darker. Murky or churned-up waters can likewise lead to low visibility that can cause sharks to confuse humans with prey.
Furthermore, spear fishing and other activities that produce blood and other scents can attract sharks, which have a very sensitive sense of smell. In addition, Shester said the risk is higher in a place where there has been a previous attack, as it can demonstrate that it’s a “sharkier area.” Beaches that are more crowded are less likely to attract sharks, so it’s a good idea to stick with more human-populated waters.
Chris Lowe, director of Long Beach State University’s Shark Lab, pointed out a seasonal connection to shark attacks, noting that “people do need to be aware that the fall season is a time when more large juvenile and adult sharks may be moving along the coast.”
Southern California is considered a nursery ground for white sharks, with juveniles moving into the region’s warmer waters from the south in the spring through early fall.
Researchers have identified a seasonal distribution pattern of white sharks in California, with juveniles mainly found in Southern California and northern Mexico, where they primarily feed on fish and invertebrates. Adults are mostly distributed north of Point Conception, gathered around seal and other pinniped breeding grounds.
Electronic tagging studies have revealed that a large number of white sharks, after foraging in California coastal waters in the fall, migrate over 1,000 miles to an area of the open ocean between Hawaii and Baja that’s been called the White Shark Café. Once assumed to be an ocean desert, nutrient-rich plant life too far below the ocean surface for satellites to detect has revealed a complex food chain that the sharks appear to be capitalizing on.
Chance of attack
It’s important to remember, Shester explained, that we are at a much higher risk for injury or death from driving or walking to the beach or swimming in the water, which can lead to drowning, than from a shark attack. He likened the chances of getting bit by a shark to “winning the bad lottery.”
An academic paper from 2015 titled “Reconciling predator conservation with public safety” by Francesco Ferretti, Salvador Jorgensen, Taylor K. Chapple, Giulio De Leo and Fiorenza Micheli calculated that in California a person “is 1817 times more likely to die by unintentional drowning than from a shark attack.”
The researchers reported that 86 injurious attacks were attributed to white sharks along California’s coast between 1950 and 2013. Thirteen of those attacks were fatal. Ferretti and colleagues wrote, “Throughout this period, there was an average of 1.37 attacks per year with an increasing trend, from an average of 0.9 attacks per year in the 1950s to about 1.5 attacks per year in the final 10 years.”
However, they concluded that while the number of reported incidents of white shark attacks had risen over the years, the chances of an individual getting attacked by a white shark had greatly declined.
In other words, it is safer now to swim in the California coastal waters than it was in 1950. The number of humans swimming and recreating in the water has increased significantly since the mid-1900s, thereby lowering the probability of a particular individual being attacked. The paper claimed that “the individual attack risk for ocean users has decreased by >91% over a 63-year period (1950 to 2013).”
The researchers found that surfers in California were attacked the most often, at 33 percent, of any recreational group. But when the attack rate was controlled for the number of people participating in a particular activity, abalone divers were found to be the most prone. Nonetheless, we’re talking slim odds.
The researchers’ study of California found, “In 2013, the chances of a shark attack on an abalone diver were one in 1.44 million or close to 0.69 attacks for every million diving days. … For surfers, the chances were one in 17 million. Swimmers had the lowest chance of shark attack, with one attack for every 738 million beach visits. …”
Shester said that we are swimming near great whites more often than we realize, just as when we’re on hiking trails we are passing near mountain lions that we don’t see. He noted, “99.9 percent of the time sharks are keeping away from us just as we are keeping away from them.”
While the idea of encountering a great white shark is certainly terrifying, humans have to remind ourselves, as Shester put it, “We are not at the top of the food chain in the ocean.”
Though we want to ensure our own safety and should take measures, Shester said we have to keep in mind that in the ocean we are visitors to a wild place, where the health of wildlife — including apex predators like white sharks — is of utmost ecological importance.