This article has been conserved for you by the Marine Mammal Center. Learn more about our Online Article Conservation Program here.
The more sediment obscures the cameras, the clearer it becomes to everyone in the cramped control room: this mission at MARS isn’t going smoothly. All the operators are trying to do today is plug a cord into an outlet. But the mundane becomes complex when you’re doing it with a remotely operated vehicle (ROV) 3,000 feet underwater in Monterey Canyon at the Monterey Accelerated Research System ocean observatory—more commonly shortened to MARS.
There lives a deep-sea universe we know only a little better than our nearest outer space neighbor. In today’s mission, we want to help people listen to what’s down there. The cable the pilots are trying to plug in is linked to a new hydrophone the Monterey Bay Aquarium Research Institute (MBARI) is setting up, replacing the old one that recorded—and live streamed—the sounds of the deep for seven and a half years.
Left: The ROV works to plug in the hydrophone into MARS. Right: The new hydrophone. (Tanvi Dutta Gupta)
What could it hear? There’s the surge of white noise as thousands of tiny air bubbles burst among the surrounding tons of water. Then, maybe, the keening of a humpback whale emerges, vibrating down the steps of a scale, or perhaps the magnified rapping of raindrops, battering the surface half a mile above.
And if you wait long enough, a mechanical clicking noise in the background will begin. People describe it in different ways: a metronome, a group of people wearing tap shoes, Morse code. The first time Will Oestreich, a postdoctoral scholar at MBARI, heard the sound, he recognized it almost immediately. Sperm whales.
After Oestreich noticed it, he couldn’t avoid it. The clicking came up more and more as experts trawled through their years of data. Oestreich asked around, trying to understand whether he heard sperm whales as much as whale watchers and researchers saw them. He got the same answer over and over—no. Everyone out on the water agreed that sperm whales were a once-in-a-season discovery, if that. For many dedicated mammal watchers, it’s the last local species they tick off their bucket lists.
Oestreich and his colleagues trawled through the seven years of continuous recording with a precise algorithm, and they found MBARI heard sperm whales out there nearly 50 percent of the time—far more often than whale watchers saw them. Their study, published in September 2024, is part of what Oestreich describes as an “explosion” of science that’s transforming our understanding of how sperm whales live. As data analysis tools catch up with the fathoms of data we’ve collected, scientists are illuminating a new side of this much-mythologized mammal. Together, they’re telling a new story of sperm whales.
Sperm whales have always stood out among the 90-something species of cetaceans in the world’s oceans. “They’re extreme in so many ways,” says Shane Gero, a biologist who studies sperm whales’ social lives off Dominica, an island in the eastern Caribbean. They’re the largest of the world’s toothed whales and carry the biggest brain of any creature in the world—as heavy as a young toddler and more than five times the volume of our brains. They could drown out a jet engine with their 230-decibel clicks: it’s the loudest animal sound ever recorded in the world. Sperm whales are among the deepest diving marine mammals we know and live more than 60 percent of their lives out of sight, surfacing about once an hour to breathe. Perhaps it’s no surprise they belong to a genus of their own: Physeter, the “blow-pipe” whale.
We have been trying to understand them for a long time. Nearly everywhere—including along the California coast—sperm whales have been a welcome sighting, though rarely for reasons as benign as a mammal checklist. Of the millions of whales massacred during the peak commercial whaling operations of the 19th to 20th centuries, sperm whales ranked among the most coveted catches.
In California, commercial whaling dates to the 1850s, with the final push lasting from about 1919 through 1971. During that later period, whaling stations along the coast reported processing about 1,000 sperm whales caught near shore, along with the humpback and gray whales targeted; meanwhile, Soviet and Japanese ships at sea harvested tens of thousands more sperm whales from the Pacific.
One of the last stations based itself in the city of Richmond. Whalers would sail from there for days at a time to the Farallones and down to Monterey Bay to hunt. Pratt Peterson, one of the last whalers in the Richmond station, said during a 1987 interview that sperm whales stood out; hunting them was “very easy” compared to more active humpbacks. To recover from their deep dives, sperm whales must stay still at the surface, blowing over and over for up to 10 minutes at a time. This makes them simple targets to sneak up behind, kill, and drag back—lugging the carcass under the Golden Gate Bridge through the Bay to Richmond. There, hunters hauled a whale ashore to disassemble it for parts—oil, bones, meat, and with sperm whales, their namesake spermaceti. A term perhaps coined by sex-minded whalers, spermaceti is a creamy wax, smelling faintly of raw milk, produced by a specialized organ in sperm whales’ heads. The search for spermaceti helped drive U.S. commercial whaling to bloody heights. Across the North Pacific, from 1800 to whaling’s international ban in 1985, whalers massacred almost half a million sperm whales.
From whales’ bodies, manufacturers made products that lit up the Western world. Lamps sparked by sperm whale oil illuminated streets and kept living rooms bright; grease slicked by sperm whale blubber lubricated the literal wheels of Western industry.
Most whaling ships left from ports in New England, where they would embark on perilous years-long voyages to catch as many whales as possible—traversing the globe in the process and often navigating the Pacific for months. For decades, as whaling crews prepared to depart from harbors in New Bedford and elsewhere, dreams of wealth, adventure, and quarry drew hundreds of eager young men to hop on board in search of sperm whales—among them future author Herman Melville.
Across these centuries of commercial whaling, no matter how many sperm whales were killed, the species remained a mystery to the whalers chasing them. Melville’s opus Moby-Dick was published in 1851, as commercial whaling reached its first peak in America. Based in part on Melville’s experiences aboard a whaling ship, his chronicles of an obsessive captain’s search for the albino sperm whale that took his leg still resonates today.
More recent science has proved many of Moby-Dick’s basic facts are wrong, says science writer Carl Zimmer. But the classic novel is just as important a story about what people didn’t know about sperm whales as about what they did. Melville’s narrator Ishmael devotes whole chapters to dissecting everything from the minutiae of a sperm whale’s head, its “lashless eye” and “wondrously minute” ears, to the “vast local power” of its “tendinous tail,” trying to understand how sperm whales lived.
Ishmael speculates freely: how did a sperm whale see, with eyes on both sides of its head? What could such small ears hear at all? How did a tail that could sink ships also move with such extraordinary grace? What conclusions he does reach are often baldly incorrect: for example, that “a whale is a spouting fish with a horizontal tail.”
At the end of his chapter “The Tail,” Ishmael ultimately gives up. “Dissect him how I may, then, I but go skin deep,” he wails. “I know him not, and never will.”
Flashes of fact emerge amid Moby-Dick’s ramblings. “There are some observations that are ahead of their time,” Gero says. Ishmael may have decided whales are fish—but the fact he recognized and noted they had a horizontal tail, not a vertical one like most fish, was “pretty smart at the time,” Gero says. After all, whales have a horizontal tail because of their mammalian hip bone.
And the data collected by early whalers in the 1800s contains critical—if gore-spattered—records of historic whale distributions. Matthew Maury, now regarded as the father of oceanography, spent months as a naval officer in the mid-1800s gathering whaling ships’ logs and compiling their data in a detailed map that remains a valuable Western record of where and when sperm whales move. His painstakingly hand-drawn map revealed that whaling ships, which at the time sailed mostly out of Massachusetts, found the most sperm whales in the Pacific. His conclusions, Oestreich says, are “pretty similar” to what the MBARI research found: sperm whales move poleward during the fall and winter from equatorial haunts.
The tools available today, though, have pushed modern sperm whale science to unprecedented depths. It has exploded as both hardware and software have advanced the ability of scientists to collect and analyze data. New biologging tags that scientists like Gero can suction-cup onto whales now let us follow sperm whales down on their dives, just as drones capture sperm whales’ surface social lives. Advances in genetic sequencing show the lineages that bind sperm whale societies. And exponential progress in computing and data analysis mean years of audio recordings, like those collected by the MBARI hydrophone, can be processed in increasingly more sophisticated ways, letting scientists like Oestreich pick out the patterns in sperm whale abundance across the hundreds of terabytes of data the hydrophone has recorded.
Before, monitoring sperm whales at eye level often left scientists with more questions than answers. Hal Whitehead, a biology professor at Dalhousie University in Nova Scotia, who cofounded the Dominica Sperm Whale Project with Gero and others, has studied sperm whales almost his entire career, starting from small boats in the Indian Ocean. “From the side, you just see a bit of whale sticking up,” he says. “They’re clearly interacting with each other, but you have no idea how.” The aerial perspective offered by drones has allowed scientists like Whitehead to watch sperm whales rolling around, kissing, and rubbing against each other—new clues to the culture that defines their social lives.
Scientists had assumed—perhaps influenced by the mostly male whalers who gave us the first comprehensive Western records—that the large “bull” whales dominated sperm whale society, with harems of females they’d occasionally visit. Moby-Dick’s aggressive pursuit of its eponymous male whale did nothing to dispel this assumption. But research by Whitehead and other scientists showed that couldn’t be further from the truth. Adult female sperm whales, he found, were “the ones who make things happen.” Males may live with their mothers anywhere from five to 20 years. But once their mother has another calf, everything changes. From a calfhood lived side by side with his mother, the male now must for a time navigate life almost entirely on his own. The matriarchs keep them at arm’s length, whether the young male wants it or not. Gero says he’s seen these young adults hang out a few miles away from their natal clan for years after their ostracization, calling and calling out without a response.
While males eventually strike out on their own—forming new relationships with other males in the process—female sperm whales live their entire lives, for the most part, in tightly knit social units. These units risk their lives to protect each other. One of the biggest natural threats to sperm whales in the open ocean are killer whales. Sarah Mesnick, a NOAA scientist who’s studied sperm whales off the West Coast, remembers watching one attack play out off San Luis Obispo in the 1990s. From the top deck on a tall ship, she and others watched the sperm whales circle together, tails out, in a perfect rosette—diffusing the potential of injury among the group. Every time a killer whale’s repeated attacks succeeded in isolating one whale, other whales would also leave the circle and—hazarding fatal injury—shepherd the stranded group member back into the safety of the rosette.
“In the animal world, it’s very normal to risk your life to save somebody you’re related to,” says Mesnick—but from the research she’d done already, she knew that most likely, none of the sperm whales protecting each other were related. “In humans, we call those heroes.”
Even when it’s not life-and-death, anyone watching a sperm whale group move will notice the careful choreography that orchestrates their lives. Sperm whales will stagger their foraging dives so a calf is rarely left at the surface by itself. Groups will spend more than an hour turning this way and then the other, coming to a “slow and messy” consensus on which direction to travel next—a democratic decision-making process, Whitehead’s research shows. These social bonds are the bedrock of sperm whale society and identity. “For a sperm whale, it’s not that I’m me, but also, and more importantly, I’m a member of this social unit,” Whitehead says.
Advances in audio recordings have shown how strong this collective identity can be—and how sperm whales use sound to define their belonging. Whitehead knew each sperm whale group had its signature click patterns, which researchers call codas: he’d heard those codas thud through his boat for decades. A landmark study last year from MIT and the Cetacean Translation Initiative, for which Gero is the lead biologist, used artificial intelligence to pull apart 13 years of sperm whale recordings from the Dominica Sperm Whale Project. It found that even as sperm whales repeated the same basic click sequence, they altered the rhythms with minor but intentional variations—changing the rhythm, adding a final click. (Oestreich notes that many acoustic ecologists—like him—play musical instruments in their spare time.)
(Tanvi Dutta Gupta)
Sign up today!
Replaying the recordings of codas, the researchers heard sperm whales clicking back and forth with each other in long exchanges. The whales combined and recombined their basic sounds over and over, in something perhaps approaching a conversation.
Oestreich hesitates to call what the researchers decoded a language: “What we mean by that definition often has a very human-tinged flavor to it,” he says. Regardless, he’s going through the MBARI recordings to see what codas can be found, to see if more can be learned about sperm whale groups passing through Monterey. And he’s also thinking about how much else researchers don’t understand. For example: some of the sounds detected are “slow clicks,” most made by adult males who click and wait five seconds or longer before clicking again. He’s fairly sure what the sound is not: it’s too slow for echolocation, and it’s not a coda. But that leaves him with yet another unsolved mystery about sperm whales of the West Coast.
As familiar as sperm whales might seem—mammals who nurse their young, who live among mothers and grandmothers—Gero says it’s important to remember that much of their experience is alien to ours. At least 60 percent of it transpires below the surface in a dark world whose lines are drawn in sound that our vision-biased brains are not physically adapted to understand. “We don’t really know much about how their brain interprets sound,” Gero says. It could be a 3D image; it could very well be something else altogether. Our attempts to infer meaning from the data we can get on sperm whales, Gero says, are ultimately “an abstraction away” from what the whales are actually perceiving.
For all that our scientific knowledge has advanced, so much about sperm whales remains speculation—and likely always will. It might have been written 174 years ago, but Ishmael’s lament still resonates.
It takes more than three tries over an hour in an increasingly claustrophobic control room. But finally, the plug for the hydrophone slides in. The entire control room bursts into applause. Eventually, the ROV begins to ascend. Just like that, we leave MARS behind: it might be months before any human instrument returns.
As we ascend, weird and wonderful creatures drift past the lights of the ROV: a deep red bloody-belly comb jelly, a long thread of a siphonophore, a silvery torpedo-shaped fish. Each flashes by for a few minutes and then disappears; each is just a small sliver of everything that’s living out here. Most of this world will live entirely out of our sight and knowledge.
And most of us will never see the sperm whales that are likely, also, swimming by at this moment. That’s not to say we haven’t changed them: sperm whale populations have only just begun to recover from the onslaught of whaling. Indeed, the last whale killed by commercial operations in the U.S. was a subadult sperm whale caught off Point Reyes and brought into the Richmond whaling station to be processed in 1971.
Populations along the West Coast likely hover around about 2,000 individuals these days—they’re stable, says Karin Forney, a scientist with NOAA who surveys whale populations off the West Coast. But they are also a fraction of what they were. Whalers preferred male sperm whales, and removing so many of them from these complex—even if female-dominated—societies likely reshaped whales’ lives in ways we’ll never quite know. Mesnick says effects of whaling could even explain why unrelated females in these societies form such tight social bonds. After all, whaling operations locally ceased just 54 years ago, and sperm whales can live for more than 70—for them, 1971 is “not that long ago,” Forney says.
We’re neighbors, sharing the same waters, even if separated by thousands of feet of depth. We’ll never be neighbors who understand each other fully. “His is an unwritten life,” Ishmael laments.
And our impact continues: sperm whales regularly wash up on our coast, some killed by ship strikes, some with stomachs weighed down, others perhaps suffocated, by nets and plastics. Gero suggests MBARI’s sperm whale recordings offer an opportunity to think about whom we share our waters with. “It’s a good time to pause,” he says. “Then maybe ask how you can change your behavior to accommodate them being here as well.”
If you’re looking for a moment to pause, seek out the archived recordings online from the Monterey Canyon. Keep them playing in the background as you live your life. Keep listening. Soon enough, the clicking will come: the tap dancer, the hammer on the anvil, the Morse code spelling out a world we’ll only ever glimpse.
