Only a few days after receiving a shark repellent bracelet for Christmas, 16-year-old Floridian Zack Davis strapped it on and paddled out for a surf at Avalon State Park beach. After riding a wave, Davis went underwater and bam! He was bitten on the arm by what experts estimated to be a five-foot blacktip shark. When the animal released Davis a few seconds later, the teenager bolted for shore, eventually receiving 42 stitches for his injuries.
Shark repellent devices like the Sharkbanz bracelet Davis wore have been flooding the surf market in recent years, and according to some accounts, are flying off store shelves. Despite their popularity, skeptics have raised questions before. And Davis’ incident even more strongly begs the question: Seriously, WTF?
These devices can use chemicals, but more commonly employ electric signals or, as with Sharkbanz, magnets to ward off the fish. But the particulars of which technology is used don’t much matter to Chris Lowe.
“It’s hard to disentangle magnets from the rest because in my opinion none of them work,” says Lowe, director of the Shark Lab at California State University, Long Beach. “None have been able to show what I would call compelling data to meet that criteria.”
Responding to the incident in an earlier article, Sharkbanz co-founder Nathan Garrison told The Inertia that the attack was anomalous. “What happened here is essentially the rarest of shark encounters where Zack jumped off his board and pretty much landed on the shark.”
Lowe offers his criticism even though he, like hundreds of thousands of YouTube viewers, have seen Sharkbanz’s promotional videos. In one of them, bull sharks are seen investigating a lump of fish inside fabric made to look like a surfer’s leg dangling from a surfboard. But when the sharks get close, they apparently sense a Sharkbanz alongside the meat and suddenly dart off without biting.
Take a look at that video below:
Other makers of repellent devices have evidence that seemingly supports their product. But there’s also evidence to the contrary — beyond the attack on Davis — including at least one instance where a shark ate a repellent device. In recent studies with electronic repellents, the Australian government found that the devices sometimes worked, and sometimes did not.
Lowe doesn’t disagree that some or all of the emerging technologies may be on to something. Or that they may improve with time. But at the moment he’s not convinced. “How do we come up with a shark repellent when we don’t fully understand how sharks perceive their environment?”
One of the problems is this: Testing performed like the demonstration in the Sharkbanz video, done by coercing sharks into what Lowe calls “scavenging mode” through the use of chum, is questionable. Why? Many sharks are ambush hunters. For example, great whites, who are known to mount attacks from below at great velocity. “How do you test that under realistic conditions?”
Put another way: “Most people who get in the water aren’t bleeding,” says Larry Cahoon, a biological oceanographer at the University of North Carolina Wilmington. “The magnets might have some effect but it’s in the wrong context.” He adds that it would not surprise him to find out there were differences in how various shark species respond to magnetic fields; shark scientists haven’t pieced that together, he says. “Some might care more than others.”
Moreover, the rate of shark attacks is so infinitesimally small, Lowe says, one in 11 million in the United States, that studying them is difficult. It’s next to impossible to determine a statistical difference between attacks that occur where no repellent device is present and those that occur where one is.
“As a person who studies shark behavior, I haven’t seen anything compelling enough to make me think, yeah, that has a real chance at being a full-fledged shark repellent. Maybe that day will come, but right now I don’t think we’re there,” Lowe says.