How Whales Found Peace in War

Story by Giuliana Viglione

On December 17, 1946, the Hashidate Maru butchered its first whale. It was a fin whale, the second-largest cetacean species on Earth. The carcass yielded over four metric tons of oil and more than 15 metric tons (33,000 pounds) of salted meat. Over the next 73 days, the ship processed a further 185 fin and 294 blue whales, returning home to Japan laden with over 3,000 metric tons of oil and almost 10,000 metric tons (22 million-plus pounds) of whale meat.

It was Douglas MacArthur, the American general acting as Supreme Commander for the Allied Powers in Japan after World War II, who sent the Hashidate Maru and another ship, the Nisshin Maru—both retrofitted Japanese military vessels—to Antarctica’s whale-filled waters. Food shortages loomed across the world, especially in Japan, which the Allies had bombed nearly into oblivion. MacArthur reasoned that the oil and meat would help relieve the hunger crisis gripping the country.

MacArthur’s directive was controversial. Australia and New Zealand were not keen to have Japanese vessels so close to their shores in the aftermath of the war. Others were concerned about the resumption of industrial whaling. Hunting had already devastated the whales of the southern hemisphere, killing an estimated 290,000 blue whales alone in the first four decades of the 20th century, and other species were ravaged as well. When nations repurposed many of their whaling ships for the global conflict, whales experienced a rare moment of respite. Scientists were skeptical that, after only six years without whaling, populations were healthy enough to withstand more whaling. “There is no evidence that the stocks of whales have recovered from the prewar condition of depletion,” William Flory, one of the signers of the International Convention for the Regulation of Whaling, wrote in a 1947 memo. “There would seem to be no more justification for killing off the breeding stocks of whales than for killing off the breeding stocks of cattle,” he added.

MacArthur ignored the feedback. The crews aboard the pair of ships ultimately slaughtered more than 2,300 blue (Balaenoptera musculus) and fin (Balaenoptera physalus) whales over the 1946–47 and 1947–48 austral summer seasons. Scientific observers aboard the ships dutifully recorded data on each specimen: length, stomach contents, whether a female was pregnant or lactating, and the size of a male’s testicles.

Acting under instructions from A. Remington Kellogg, a premier whale expert and the curator of what was then called the United States National Museum, which was administered by the Smithsonian Institution in Washington, D.C, the ships’ crews also cut the two longest plates of baleen out of the mouth of each whale they killed. Whales without teeth—such as fin and blue—rely on these flexible plates made of keratin to filter feed from the sea. Baleen grows from a whale’s upper jaw downward, lined up like the slats of window blinds. Kellogg suspected that baleen was like tree rings and that by counting the layers on a plate, he could definitively determine the lifespans of the two species.

But when he received the plates—crates and crates of them, with some nearly a meter long—Kellogg realized his error. Baleen in adult whales erodes at the tips as it grows from the gums. So a single plate captures only a small fraction of the animal’s long life. Baleen records a roughly four-year period of life for fin whales and a six-year period for blue whales. Embarrassed by the amount of work expended for a collection he now believed was useless, Kellogg stashed the baleen away in the Smithsonian, where it sat, forgotten, for more than 60 years.

It was John Ososky, a collections specialist at the Smithsonian National Museum of Natural History, who began to unravel the mysteries of the Japanese-procured baleen. In 2012, Charley Potter, who oversaw marine mammal collections for the museum at the time, stumbled on the collection in an off-site facility and asked Ososky to figure out where the mysterious baleen had come from. The collection had some link to Japan—that much was clear to Ososky from the wooden tags affixed with thick wire to each piece of the baleen. Beyond that, there was little to go on; documentation is often spotty on older research collections.

Ososky spent countless hours digging through the Smithsonian’s archives for clues, eventually uncovering reams of correspondence regarding the Japanese whaling expedition, including some between Kellogg and MacArthur’s office. A colleague with contacts in Japan helped Ososky track down the ship manifests from the four voyages. But determining the provenance of the baleen was just the start. To turn the crates of baleen into a usable collection for researchers, Ososky needed to match each piece to the ship logs and all of the information they contained. One problem was that on each ship the workers numbered the specimens starting at one for each whaling season—no other identifying information appeared on the tags. Also, the crews were inconsistent in their labeling systems, switching between ink colors or tag styles multiple times during each voyage.

When I meet Ososky at a coffee shop near his house in Maryland, he is wearing a black shirt emblazoned with a whale skull. His tangled eyebrows obscure the top of his gold wire-rimmed glasses. His smile is broad, revealing the glint of two crowns in the back of his mouth. He gets animated easily, gesturing with both hands as he explains how he pieced together the story of the baleen.

The breakthrough happened in 2017, when Ososky decided to photograph each individual piece of baleen and sort the pieces visually, grouping together those with similar tags. Fin whale baleen is shorter and lighter in color than blue whale baleen, and they are easily distinguishable from each other. By comparing the sequence of plates in each grouping—say, two fin whales followed by three blue whales and then another fin whale—to the observers’ logs, Ososky could slowly match each set to the expedition it came from. Although the job was daunting, at no point did he consider giving up on the collection. “Once it was tasked to me,” he says, “I just sort of became obsessed with it.”

When he finally cracked its code, he could link each piece to its place in the story of those two whaling seasons. Ososky knew he had something valuable. The baleen itself, combined with the ships’ logs, opened the possibility of answering a whole host of questions that would have otherwise been impossible to resolve. In recent decades, scientists had developed molecular analyses to measure steroid hormones from a wide range of animal tissues beyond blood: bird feathers, snake skin, turtle shells, mammal hair. Hormones act as chemical messengers in the body, regulating a range of bodily functions. Steroid hormones are a particularly robust class of hormones that includes testosterone, pregnancy-related hormones such as progesterone, and cortisol—a key indicator of stress.

The signatures that hormones leave behind in tissue can shed light on the lives of contemporary wild animals and populations and even offer glimpses far back in time through specimen collections. Standing on Ososky’s shoulders, researchers could use the Smithsonian’s baleen to knit history and chemistry into an unprecedented look at the internal experiences of whales during the killing spree that MacArthur sanctioned.

One of the researchers at the forefront of developing new methods of hormone analysis in animals is Kathleen Hunt, a wildlife endocrinologist at George Mason University in Manassas, Virginia. Her office is a sort of shrine. Everywhere I turn, there’s a different whale: a plastic one with an articulated jaw; an illustration of a bowhead whale labeled with Iñupiaq terms for each body part; a sign that says “whalecome.”

Noninvasive techniques are crucial for studying baleen whales, Hunt explains, because the animals are too big for researchers to capture and examine. With many animal species, scientists can take blood samples to measure their hormone levels in the moment. But obtaining blood samples from whales is tricky, so researchers have had to get creative.

Hunt got her start studying whales by looking at hormones in fecal matter. Whale feces are fairly buoyant; if a whale poops near the ocean’s surface, the feces will float and scientists can scoop them up and take them to a lab for analysis. But it’s difficult to gather much data this way. “The basic problem is whales won’t poop on command,” Hunt says. “You can follow them around and they just won’t poop. You can spend the whole year trying to get poops and end up with five”—which provides only sporadic, brief glimpses of a whale’s life.

Fortunately, there are other options. “Steroid hormones just permeate your body,” Hunt says. “Any little thing that’s growing out of the skin—hormones are being deposited into it as the blood circulates.” She grabs a chunk of her thick copper-colored hair and stretches it away from her head. “That’s… I don’t know, five months [of growth],” she says. “So I could measure the cortisol of this segment and this segment and this segment and this segment, and I could reconstruct how stressed I’d been on average.”

When it comes to stress, we are not so different from our wild kin: exposure to stressors elevates the heart rate, increases sweat production (in those animals that do sweat), increases anxiety and vigilance, and causes spikes in glucocorticoid hormones, such as cortisol. In fact, “as far as we can tell, the mechanisms and the biology of stress is nearly identical in humans and wild animals,” says Michael Romero, a biologist at Tufts University in Massachusetts. Repeated exposure to stressors can lead to either long-term increases in cortisol or long-term decreases—“both of which seem to be a problem for health,” Romero explains.

Some amount of stress is healthy; it’s what triggers the fight-or-flight response when an animal comes face to face with a predator. “If you’re being chased by a lion, your epinephrine”— also known as adrenaline—”is gonna kick in, and you’re gonna run as fast as you can, and your heart [rate] is going to increase. And for the short term, you’ll be okay,” says Tracy Romano, a marine mammal expert and the chief scientist at the Mystic Aquarium in Connecticut. “If you were being chased by a lion day after day after day, that would probably be a bad thing.” Being exposed to stressors repeatedly can erode that stress response, affect reproductive cycles, and even wear down an animal’s immune system.

Back at her office, Hunt springs out of her chair to grab a piece of baleen propped against her bookshelf. She holds it out to me over the coffee that she’s left untouched on her desk during our wide-ranging conversation. A thready fringe sprouts from the edge where the keratin that makes up the baleen has worn away from weeks and months and years of filtering krill from seawater. It was this texture that led Hunt to her own baleen breakthrough about a decade and a half ago.

That’s when Hunt received a call from Raphaela Stimmelmayr, a wildlife veterinarian and research biologist at Alaska’s North Slope Borough. The North Slope Borough is the northernmost county equivalent in the United States, and its residents are predominantly Iñupiat. Because people there rely on whaling for food and to maintain traditional ways, the borough has its own research program to help ensure that bowhead whales are sustainably managed and used. Stimmelmayr had been reading some new scientific journal articles for which researchers had measured hormone levels from hair samples. Stimmelmayr told Hunt, “I’m looking at a piece of bowhead baleen and it looks to me like it’s made of compressed hair.”

“The second she said that, I was like, ‘Oh my god,’” Hunt says. As a test, Hunt and Stimmelmayr sampled a few pieces of baleen—some from whales that were pregnant when local hunters killed them. Pregnant whales would have a certain hormonal signature, measurable in their baleen–much like pregnant humans have in their hair. The results showed that their hypothesis was correct: the progesterone at the base of the baleen from the pregnant whales was significantly higher than it was in the same location on the baleen from those who weren’t.

A few years later, a biological oceanographer named Alyson Fleming reached out to Hunt. Fleming, at the time a postdoctoral scholar at the Smithsonian, had come across a unique collection of baleen—Ososky’s labor of love—in the museum catalog, and she wanted Hunt’s help.

The baleen collection is housed at the Smithsonian Museum Support Center, tucked away on a Maryland state road just a few kilometers over the state’s border with Washington, D.C. Were it not for the security guard, who checks my name against a visitors list before waving me into the parking lot, I would have mistaken it for a self-storage facility, or maybe a high school.

Michael McGowen, who is the current curator of marine mammals at the museum, guides me through the entrance to the central building and down a hallway past a taxidermic polar bear rearing on its hind legs, then through a double set of doors and into a low-ceilinged room. The space is cool in both temperature and lighting, and it’s filled with rows of identical-looking cabinets. About a third of the way toward the back of the room, we stop. The printed legend stuck to the end of the row tells me that the 32 cabinets ahead—bookended between Mineral Science, Corals, and Amphibians—hold the Japanese baleen collection.

McGowen opens the first cabinet to reveal baleen plates loosely wrapped in thick, translucent plastic sheeting. The plates are warped with age and pockmarked where bugs have burrowed into the keratin. Each splinters at its edges into coarse bristles, like a well-worn straw broom. Some of the plates have wooden tags affixed to them with thick-gauge wire—the original wires used to fasten identifying tags to each baleen plate. Sorrow washes over me, knowing that what I see before me is all that remains of dozens of the largest animals ever to roam the Earth.

Next, McGowen leads me to the “whale warehouse,” where most of the rest of the cetacean collection is stored in decidedly non-warehouse-like, climate-controlled conditions. The lights flicker on, revealing a row of baleen whale skulls propped up like headstones in a graveyard. The cavernous building has an unfamiliar musty smell, and I keep inhaling deeply to try to place it. It’s whale oil, McGowen explains—oil that is still seeping out of the bones of these magnificent creatures. The same oil that caused industrial whalers to drive many species of whales to near extinction. Despite the morbid scene around me, I feel a bizarre urge to lick the bones. McGowen advises me against it, then ushers me to a comically large drawer several meters wide. Inside is a piece of bowhead baleen that is etched like a ruler. Each groove, carved by a researcher, is a data point in a reconstructed timeline of that part of the whale’s life. 

Back in 2019, after Hunt and Fleming first chatted about the long-forgotten Smithsonian baleen collection, the pair’s proposal was funded. They began analyzing the specimens with Malia Smith, one of Fleming’s graduate students; shortly after, a young woman named Allie Case, who had conducted hormone research during her undergraduate degree, joined Hunt’s lab as a graduate student.

When Case and I speak, she’s still in the hazy liminal space of someone who’s recently finished a master’s degree. She tells me that after she defended her thesis, Hunt told her to “make sure to save your hair because your cortisol from your defense is in there, and I want it.” Case says she still isn’t sure if Hunt was joking or not. Then, she walks me through the work.

From the 3,200-odd pieces of baleen in the Japanese collection, the team selected 10 for analysis, all of them from whales that had been killed during the second whaling season. They looked for the longest plates, so that they could peer as far back in time as possible, and used the observers’ logs to ensure they had a diverse sample, representing male and female whales, blue and fin whales, pregnant and non-pregnant whales. For each whale they studied, Hunt and Case—under Ososky’s protective watch—drilled small channels in the baleen plate at one-centimeter intervals and collected the resulting powder. Back in the lab, Case mixed the pulverized baleen with methanol to extract four hormones from the solution: progesterone, testosterone, cortisol, and corticosterone, another stress hormone.

Returning to the same plates of baleen, Fleming and her team extracted and analyzed carbon and nitrogen isotopes. Isotopes are atoms of the same element that vary slightly in mass from one another. The isotopes in the baleen come from the food the whales were eating: different food sources have different ratios of isotopes depending on the environment in which they grew, and the things they themselves consumed. They wanted to get as much information as possible out of the baleen each time they made a hole through one.

Isotopic work and hormone analysis “tell you different parts about an animal’s story,” she says. By looking at the ratios of different isotopes of the same element, the group could determine where and when blue and fin whales were feeding. They learned that while the fin whales they studied from the Japanese collection had migrated to the Antarctic in the summer and headed farther north in the winter, a population of blue whales seemed to have stayed in the Southern Ocean year-round.

The isotopes also served as a calendar of sorts. The ratio of the heavier carbon isotope to the lighter one goes up and down as a whale’s food source changes during its migration. A year can be worked out by measuring the physical distance on the baleen between the nearest points with either the most or least amount of the heavy isotope in the ratio—representing the return of the whales to the same feeding grounds. 

When Case used those isotopic timelines to put all of her hormone analyses together, she saw a signal that confused her. There was a huge spike in stress hormones around 1946 for all 10 whales she had studied, and she didn’t know why. Puzzled, Case brought the data to Hunt. From Ososky’s archival work, Hunt knew all about the pause—and resumption—of whaling in the Antarctic. When she saw the spike, she recognized another potential eureka moment. “I was like, ‘That’s the year the whaling started again,’” she says. “I thought, ‘It couldn’t be that simple.’”

Hunt and Case were cautious about attributing the whales’ stress to the resumption of whaling in the Antarctic, especially at first. Instead of calling it a “whaling effect,” Hunt preferred to refer to it as a “year effect” of unknown origin that occurred in 1946. But when she and Case presented the work at scientific conferences, their fellow scientists gave them the same feedback over and over: “You could be a lot stronger about your whaling story.”

One by one, Case and Hunt went through alternative explanations for the stress. Maybe, they thought, the increased stress related to pregnancies. But when they looked at only the male whales, the signal persisted. They looked at oceanographic conditions in the 1940s, but the known climate shifts occurred earlier in the decade, not in 1946. With each explanation they discounted, the case that whaling was the cause became incrementally stronger.

But only half of the whales in the museum collection were killed during that first whaling season. How could just two ships—even death factories capable of killing and processing hundreds of whales in a four-month span—create such a strong stress response in whales that weren’t caught and killed until the next year? Hunt puzzled over this question. As she delved into the literature on how the whaling vessels operated, her doubts quieted. The Nisshin Maru and the Hashidate Maru were just the factory ships, where whales were processed into meat and oil. Each vessel was accompanied by at least half a dozen other smaller ships that actually pursued and killed the whales before dragging them back to the factory ships for dismemberment. And the Japanese ships weren’t alone—the Soviet Union also resumed whaling in the Antarctic shortly after the Second World War.

What’s more, whales aren’t just randomly distributed throughout the ocean. During summer months, populations in the Southern Ocean tend to congregate at the edge of the Antarctic sea ice to feast on krill. Industrial whalers knew this well—so much so that scientists have used historical whaling logs to re-create maps of past sea-ice extent.

If the whales were concentrated in a very specific area, where they were being chased not just by one ship but by several, individual whales could have internalized the trauma of a population under attack. “Whether that’s a direct response to whaling activities, whether that’s indirect—to the presence of ships in general—we wouldn’t be able to tell, but compared to the earlier plates, you can definitely see the rise,” Case says.

What must it have done to those whales that avoided a gruesome end aboard the two factory ships? To hear the calls of their kin silenced one by one, replaced by the never-ending droning of ships as worldwide marine traffic ratcheted up? To be chased by vessels themselves? To know, perhaps, how close they had come to death?

Imagine, for a moment, a parallel universe—one in which industrial whaling didn’t resume after the World War II.

Maybe MacArthur heeded the warnings of his compatriot, William Flory. Maybe the Allied Powers found another food source. Maybe the International Convention for the Regulation of Whaling, which established the International Whaling Commission to govern the whaling industry and conserve whale populations, outlawed commercial whaling from the outset—rather than letting it continue, in some form, through 1982. It’s hard to say just how much of a difference a few extra decades of recovery would have made to blue and fin whale populations that had already been harvested so ruthlessly. But perhaps it would have been profound for the whales that survived the peak of industrial slaughter to just be left alone.

What would a return to a more “normal” world have looked like for those gentle giants? And what does whales’ world look like now? Hunt’s lab and others are trying to find out, sampling baleen from bowhead whales that were slaughtered as far back as 1850 and as recently as just a few years ago. “What I want to do is build the grand story of ‘How have our impacts on whales changed over the last couple centuries?’ Not just this year versus last year,” Hunt says.

While today’s cetaceans no longer face industrial whaling at the scale they once did, other threats have only multiplied. “Whales are stressed more than ever now,” says Romano, the Mystic Aquarium’s chief scientist. They have to contend with human-driven climate change and pollution, as well as the ceaseless clanging of tens of thousands of ships crisscrossing the ocean each day. This underwater noise pollution can alter their behavior, drown out their calls, damage their hearing—and elevate their stress levels.

Scientists “often have this reluctance to prescribe too much interpretation to how an animal feels,” Fleming says. “To see something like a stress signal correlated with the presence or absence of whaling is really alarming.” We might not know the internal workings of whales’ minds, but the stress signals clearly show that they have a visceral reaction to changes in their environment. While researchers work to better understand the effects of sublethal stress on animals, the baleen offers a sobering reminder that wildlife is far more attuned to changes in the world than many people might think. Human activity can have profound and wide-ranging impacts on animals’ experience, literally etching itself into the fibers of their being.

The baleen work also underscores the value of museum collections. What industrial whalers did to the world’s cetaceans is a tragedy of unimaginable proportions. “You’re never going to get that kind of data ever again,” Ososky says—nor should you. The least we can do today is learn from the sins of the past by studying what the whalers left behind and use that knowledge to help craft a future where whales have much less to fear.

And as scientists continue to develop new techniques, the mysteries they can solve from baleen and other specimens will only increase. Remington Kellogg couldn’t have imagined the ways his baleen collection would offer insight into whales’ internal experience. We don’t yet know the questions that the collection could answer in the future.