Forget the smell of blood and all the shark fears we’ve internalized thanks to “Jaws” and “Shark Week.” Turns out, the first thing a shark notices about humans actually might be the unique sounds we make in the ocean.
And great white sharks — at least the ones in a sharky hot spot like Southern California — have really, really good hearing. Whether you’re swimming or kayaking or paddling on your surfboard, even a juvenile can detect you from as far as 100 feet away.
While this might sound like the start to another horror movie — especially with more sharks and more people seeking respite in the ocean amid record-breaking heat waves and a looming El Niño — there is good news. A new study shows that even though sharks react to human noises, they often can tell from just our splashing that we’re not worth the nibble.
“There are dozens — if not potentially hundreds — of encounters daily at a beach with a lot of sharks and people. Why aren’t people being bitten? How do we explain this?” said Chris Lowe, director of the celebrated Shark Lab at Cal State Long Beach. “We worked our way through all the different senses that a shark could use to go, ‘that’s a person,’ and we thought sound and vibration might be the most influential one.”
Researchers with the Shark Lab at the California State University, Long Beach have found that sharks and humans swim together at some California beaches more often than previously thought.
(Jake Miller)
For years, Lowe and his lab have documented white sharks getting very close to people in the water. The shark’s approach is never rushed or aggressive — it’s more like something piques the shark’s curiosity from dozens of feet away, and then as the shark creeps in closer to investigate, it loses interest and just swims on.
The Shark Lab eliminated sight (limited horizontal visibility) and odor (disperses too quickly in water) as the reason a shark might react from so far away. So the researchers started looking into sounds and vibrations, which can travel quite far underwater. (Sharks also have enlarged “macula neglecta,” or sensory hair cells, in their inner ears, which make them exceptionally more sensitive to the direction where a sound is coming from.)
In a first-of-its-kind study, the lab designed a hearing test of sorts for sharks. Using a special multichannel hydrophone that can capture not only sounds but also the 3D movement of them, scientists methodically recorded themselves doing three common ocean activities: freestyle swimming, kayaking and paddling on a surfboard.
They then played back the “sound bites” at different distances underwater and observed whether a shark would change its angle and move toward the speaker.
This study is ongoing, but the preliminary findings are striking: Sharks clearly can differentiate the three water activities, and it’s also clear that the louder, more erratic sound characteristics of freestyle swimming (which happen to be in the same frequency range as the sounds of a struggling fish) can make a shark more likely to approach from a distance.
CSULB Shark Lab researchers tag a juvenile great white shark off the California coast.
(Cal State Long Beach Shark Lab)
With paddling on a surfboard, the sharks clearly could recognize the sound, but they more often tuned it out like background noise. And the gentle, more continuous sounds of kayaking elicited little reaction, said Whitney Jones, who led and designed the study.
“This is the first study to empirically show that they seem to be using sound to cue into people at these greater distances,” said Jones, who specializes in underwater acoustics and behavioral biology. “We have so much anecdotal evidence that these juvenile white sharks are habituating to people in the area just by growing up around them, but this is one of the first steps to showing that empirically.”
As for how these initial findings can translate into beachgoing tips, that depends on what feels too close to comfort. The sound of swimming is more likely to attract a curious shark, so if you want extra peace of mind, go into the ocean with a group of people. A cluster of loud humans is an even clearer indication to a shark that you are not any kind of species they would eat.
(Also avoid wearing flashy jewelry, which a shark could mistake for fish scales, or swimming in murky water, which increases the chances of startling a shark. And if you’re kayaking, think twice before bringing fish on board.)
It’s important to remember that sharks require a strong dose of caution, but the chance of being bitten — as long you don’t provoke them — is incredibly low. Last year, there were only 65 unprovoked shark bites across the entire world.
Out on Cape Cod, another great white hot spot, Jaida Elcock, a shark biologist with the Woods Hole Oceanographic Institution’s Marine Predators Group, said the more data, the better when it comes to dispelling our society’s collective misunderstanding of sharks.
“We can’t let fear get in the way of respect,” said Elcock, who co-founded the nonprofit Minorities in Shark Sciences and runs @soFISHtication_, a popular animal-facts page on Instagram and TikTok. “Sharks can tell us a lot about the health of our oceans, and there’s so much more to learn from them.”
Indeed, at more than 400 million years old, sharks have outlived five mass extinctions and could teach us a thing or two about surviving in a changing climate. It’s also worth noting that there are more than 500 species of sharks, and none of them eat humans. (The largest shark in the world, the whale shark, is actually a filter feeder and couldn’t swallow you even if it tried.)
“Sharks can be found in every type of ocean ecosystem — they’re deep sea, they’re in shallow reefs, there’s even an arctic shark,” Elcock said. “If we don’t even fully understand how they function in the world the way it is now, it is going to be even harder for us to understand how those vital parts of our ecosystems will function as the ocean continues to change.”
In other sharky news
The Shark Lab at Cal State Long Beach actually is running out of funding and in danger of shutting down a significant portion of its operation by September, as my colleague Kori McNair reports here. The lab had received a $3.75-million state grant in 2018 to run the California Shark Beach Safety Program for five years.
If comedy’s your thing, there will be a special show on Friday at the Hollywood Improv, where “comedians will take on iconic scary movies in a special pro shark, pro conservation” edition of Horror Nerd, hosted by comedian Samantha Hale. The evening will be dedicated to the Shark Lab.
And for “Shark Week” fans, Mark Kennedy at the Associated Press breaks down some of this year’s highlights, which include a feature off the Korean Peninsula with Rei Ami, whose voice helped fuel the hit movie “KPop Demon Hunters.”
One more thing
The Honolulu Museum of Art will be doing a special screening on Saturday, Aug. 22, of “Out of Plain Sight,” the documentary I directed with Daniel Straub. The film is a cinematic expansion of my reporting on the legacy of DDT and toxic waste dumping off the coast of Southern California, and I am grateful to see this film resonating with audiences across the world. (We recently received a special jury citation from AFO’s International Festival of Science Documentary Films in the Czech Republic, and the film has been awarded some of the highest honors in environmental filmmaking, including the Jackson Wild Media Award for best investigative film.)
The screening starts at 6:30 p.m., and I will be there with the University of Hawai’i at Mānoa’s Institute for Sustainability and Resilience, as well as the university’s Better Tomorrow Speaker Series and Punahou School’s Davis Democracy Initiative. Come say hello!
This is the latest edition of Boiling Point, a newsletter about climate change and the environment in the American West. Sign up here to get it in your inbox.
For more coastal and ocean stories, follow @rosanna.xia and @outofplainsightfilm on Instagram.
