Lorenzo Rojas-Bracho was in mourning. Beyond the windows of his hillside house in Ensenada, Mexico, the sun glinted brilliantly off the waters of the Pacific, but he'd drawn the curtains closed. In his living room, hanging above plush leather furniture, were whimsical paintings of the subject of his grief—a chubby, 4-foot-long porpoise called the vaquita (Spanish for “little cow”). Found only in the upper reaches of the Gulf of California, where the Colorado River meets the sea, the vaquita is the goth kid of the cetacean clan, with dark markings around its eyes and mouth and a reputation for extreme shyness. It is also the most threatened marine mammal on earth. Over the past 20 years, the species' population has fallen by a staggering 98 percent. It's officially listed as critically endangered, but even that term feels like a wild understatement; today there are perhaps a dozen vaquitas left.
Rojas-Bracho, a marine biologist, has been in love with aquatic mammals for most of his life. When he was 7 years old, he visited SeaWorld and offered his services as a killer whale trainer. (“They said no, of course, but they were very kind,” he recalled.) Now he is the head of the International Committee for the Recovery of the Vaquita and an idol among Mexican conservationists. A tall, wiry man with scholarly glasses, a salt-and-pepper goatee, and the disposition of a cool uncle, he takes a patriotic sort of pride in the porpoises. In the million years or so since their ancestors swam up into the Gulf, vaquitas have become exquisitely adapted to their special cul-de-sac: Their dorsal fins and flippers are proportionally bigger than other porpoises', to dump heat when the water temperature breaks 90, and their echolocation is finer than a dolphin's or a bat's, allowing them to thrive in conditions so turbid that a diver just 15 feet down can't see his own hands. What's more, they're cute. An old Gulf fisherman who was lucky enough to have seen one on a few occasions told me, “You almost want to cuddle it and pet it. It's such a defenseless animal.”
Those who study the vaquita must handle disappointment well. But when I visited Rojas-Bracho in Ensenada, he wasn't his usual stoic self. A few months earlier, in the fall of 2017, he and his longtime collaborator Barbara Taylor, a marine mammal geneticist at the Southwest Fisheries Science Center in La Jolla, California, had helped mount the first attempt to take vaquitas into captivity. With more than $5 million in funding from the Mexican government and outside donors, they had assembled a fleet of 10 boats, a custom-built floating porpoise pen they called el Nido (“the Nest”), and a team of 90 people from nine countries—acoustics experts, spotters, animal handlers, veterinarians—along with four US Navy-trained bottlenose dolphins. The project had ended in tragedy. “I still cannot talk about it without crying,” Rojas-Bracho said.
The captivity expedition had capped off nearly a century of trouble for the vaquita. Like tigers, elephants, rhinoceroses, and pangolins, all of which teeter on the brink of extinction, the porpoise has been obliterated, indirectly, by China's reckless appetite for exotic animal products. In the 1930s, Chinese fishermen started landing huge catches of a giant croaker fish called the bahaba. The species, which grows to 6 feet long and weighs up to 220 pounds, was prized for its swim bladder, or maw, an organ that helps ballast the animal. Although made up mostly of collagen, maws of all kinds are a popular medicinal supplement; they're sold dried and prepared in soup. Bigger is supposedly better, and the bahaba's is huge. By the middle of the 20th century, overfishing had decimated the species, so maw traders turned to the next best source, an equally giant Mexican croaker called the totoaba. Every winter, it swam north to spawn off the coast of a small Gulf town called San Felipe, smack in the middle of the vaquita's only habitat.
The ensuing gold rush was catastrophic for fish and porpoise alike. At first, the totoabas were so plentiful that they could be harpooned from the beach, butchered for their maws—which, when dried, resemble colossal potato chips with unappetizing tendrils—and left to rot. But as the population dwindled, fisherman turned to new methods. Near the Colorado River estuary, they laid gill nets, aquatic weapons of mass destruction designed to hang in the water column and ensnare passing prey. Vaquitas have the fatal misfortune of being nearly the same size as totoabas, so the nets were disastrous for them.
The Mexican government banned totoaba fishing in the 1970s, but the killing never really stopped. By 2017, Rojas-Bracho and Taylor faced a difficult decision. With vaquitas stuck in critical decline, what else could be done? They'd talked about setting up a captive breeding program for years, but the expense and complexity had never seemed worth the risk. Now, though, it was time for a Hail Mary. That summer, Rojas-Bracho's boss, the Mexican environment minister, gave him the go-ahead to assemble his armada.
The team had four weeks to pull it all off. Early on in the effort, the vaquitas showed a knack for slipping past the researchers' nets, or just disappearing altogether. Then, with one week remaining, everything changed. “It was a gorgeous day,” Rojas-Bracho recalled, sinking into his sofa. “I was far away from the action, but I could follow by radio. They were saying, ‘We have the vaquita, it's behaving very nicely, it's coming to the net. We've got it on board, it's a female, it's a great animal, it's very calm.’ ” Rojas-Bracho motored over to take a look. It was the closest he'd ever been to a live vaquita. “I could see my eyes in her eyes,” he said.
As the sun set and the sea darkened, the team introduced the vaquita to its temporary home, el Nido. At first, it swam erratically, taking the measure of its new surroundings. Then it started to adapt. Rojas-Bracho was seated on deck, taking it all in. He heard one of the vets say to the vaquita, “You're doing well, baby,” so he stood up and walked away to call the environment minister. By the time he hung up, the situation had changed dramatically.
“The animal started behaving wildly, and then it stopped breathing and it started to kind of sink,” he said. “Then there was a decision to take it out of the water and do CPR for three hours until it died, and that was painful. Jesus, it was painful. Seeing the best vets in the world trying to prevent the vaquita from dying, saying, ‘Come on sweetie, you can do it, you can do it,’ it was …” He sighed quietly and lifted his glasses to wipe his eyes.
The scientists' terrible night wasn't over. They took the vaquita onshore and performed a necropsy. Rojas-Bracho didn't sleep. The next morning, everyone agreed to shelve the captivity project.
It should never have come to this, Taylor and Rojas-Bracho thought. People had known of the vaquita's plight for decades, and they'd also known precisely how to stop it. An animal that should have been a conservation success story—Mexico's answer to the bald eagle or the bison—had instead become a parable for the age of mass extinction.
Yet all was not lost. During the necropsy, the team had harvested a few tissue samples, consisting of millions of live vaquita cells. Stored in a lunch cooler, they were driven north, through the desert and across the border, and delivered to Phillip Morin, a population geneticist whose office is next door to Taylor's. Morin brought them to the San Diego Frozen Zoo, a sort of genetic safe-deposit box for threatened, endangered, and extinct animals.
Conservation biologists have always played the role of the unheeded prophet. They may spend decades studying a particular plant or animal, and by the time they've amassed enough peer-reviewed data to make solid recommendations about how to save it, their expertise is often met with a shrug. Political or economic needs usually trump nonhuman ones, and so conservation never quite keeps pace with extinction. This is bad news for all species, but especially for those already trapped in what biologists call the extinction vortex, a spiral of mutually reinforcing threats that include predation, poaching, disease, pollution, natural disasters, habitat destruction, and genetic factors. The questions that conservationists must ask themselves can be unpleasant: How to triage so many at-risk creatures? How to decide what lives and what dies?
That was the problem on Rojas-Bracho's mind the first time he walked into Taylor's office in La Jolla as a young PhD student in 1993. He'd just examined mitochondrial DNA from a couple dozen vaquita corpses and had found, to his astonishment, that each contained the same key sequence in the control region—an area known for its high variability. This is very unusual, Taylor told me; it's as though every human in the world shared the last name Smith, without even a single Hernandez or Wang. Biologists typically treat this as a dire sign. In small populations, one of the biggest threats to long-term survival is a phenomenon called inbreeding depression. Left without many mates to choose from, animals end up reproducing with their relatives, with the result that harmful traits sometimes become concentrated in the population.
Strangely, though, the vaquitas showed no outward signs of inbreeding or poor health. Rojas-Bracho had dropped by Taylor's office to ask whether, when he published his study, journalists and lawmakers would assume vaquitas were doomed—too far down the extinction vortex to be worthy of conservation.
Intrigued by Rojas-Bracho's question, Taylor began delving more deeply into the vaquita's DNA, using computer simulations to peer back into its evolutionary history. How could an animal with so little genetic variation have so few bad mutations to show for it? Eventually, she came up with a hypothesis: The risks posed by inbreeding are generally greatest when a population goes from large to small in a very short period of time. Parts of the gene pool suddenly drain away, and you're left with a random assortment of traits. Dangerous or even fatal mutations can start showing up more often. The secret to the vaquita's fitness was that its population had been small for a long time. Natural selection had worked its slow magic, purging bad variants from the gene pool over millennia.
In the summer of 1997, Taylor and Rojas-Bracho undertook their first vaquita census in the Upper Gulf. It set the tone for the next two decades of research. The air-conditioning on their boat broke down in the 100 degree heat. One scientist cracked his spine in a fall. The Mexican navy boarded their ship regularly to check for drugs. Then a hurricane came roaring up the Gulf. “But we came up with a good abundance estimate!” Taylor said: 567 vaquitas. It was the first time either she or Rojas-Bracho had seen the animals alive.
The question now was why, in the absence of inbreeding, the vaquita population was dying off. Taylor and Rojas-Bracho eliminated the possible threats one by one. A few scientists had blamed the damming of the Colorado River, which sometimes didn't even reach the Gulf anymore. Others had blamed pollution. Yet the vaquitas were eating well, and their blubber was free of contaminants. In a pair of papers published in 1999, Taylor and Rojas-Bracho concluded that gill netting was the main cause of the species' decline. Left in peace, the porpoise would recover. Rejecting what they called “the hypothesis of certain doom,” they recommended changes to fishing regulations. “If the vaquita goes extinct, it will be the first species to have done so by gill net, and gill net alone,” Taylor told me.
An eye-opening expedition to China seven years later foreshadowed a worst-case scenario for the vaquita. Taylor traveled to the Yangtze River to look for a dolphin called the baiji. Her team encountered heavy industrial pollution, dams, fishing, overdevelopment, and so much boat traffic that it reminded her of an LA freeway. What they did not encounter was a single baiji, and the animal was soon declared all but extinct. “A 30-million-year-old species disappeared when nobody was looking,” Taylor said. She realized the need to keep a closer eye on the vaquita. Shrimping was the main fishery in the Upper Gulf at the time, and even those nets were killing the porpoises at a rate of 8 percent a year, the data showed. “It was a horrible rate of decline, but it still gave us time to fix things, and we really thought we were fixing things,” Taylor said.
Then, thanks to China's 21st-century economic miracle, which increased demand for expensive maw, the totoaba gold rush in Mexico resumed. “It just seemed like it was overnight,” Taylor told me. According to an undercover investigation by Earth League International, a black-market supply chain sprang up: Illegal totoaba cartels, some of them loosely affiliated with Mexico's narco-traffickers, smuggled the maws to China, where large specimens might fetch $80,000 per kilogram—more money, by weight, than gold or illegal drugs. They were a versatile status symbol; many people chose to mount them on their walls, give them as wedding gifts, purchase them as investment vehicles, or even pass them off as bribes to local officials. Fishermen who once made $600 a month toiling for shrimp under the sun could now earn $5,000 or more in a single evening. Meanwhile, vaquitas began dying off at a rate of roughly 35 percent a year.
In 2011, as though with the porpoise in mind, the journal Trends in Ecology and Evolution published a spirited exchange between two groups of researchers on the conundrum at the heart of conservation biology: When a species is swirling down the extinction vortex, how do you decide —quickly and accurately—what to do? The debate focused on the so-called 50/500 rule, first proposed in the 1980s, which says that in order for a species to survive, it must have at least 50 breeding-age individuals in the short term and 500 in the long term. Intended as a sort of back-of-the-envelope calculation, the rule had a couple of limitations: It took account only of genetics and inbreeding, excluding all the other threats a species might face, and it aimed to apply a universal standard to creatures as different as a gorilla and a condor.
One group of researchers, made up of Australians and Brits, had recently proposed that the long-term number be revised upward, to 5,000. It wasn't a perfect system, they wrote, but it was better than no rule of thumb at all. “Conservation biology is a crisis discipline akin to cancer biology, where one must act in a timely manner on the best information available,” they wrote. As the climate crisis worsened, so would the need for quick decisions. A second group, consisting mostly of American researchers, was having none of it. Each species, they wrote, deserved its own case-by-case analysis. It was a sin to use scientific guesswork to decide whether an animal “should be tossed from the ark.”
In 2015, at Rojas-Bracho's urging, former Mexican president Enrique Peña-Nieto banned most gill net fishing in the Upper Gulf, a cataclysmic prohibition in a region whose economy is at least 80 percent fishing-related. That stick came with a carrot in the form of a compensation plan to pay local fishermen not to fish. The problem was, all the money was given to the local fishing bosses, who owned the boats and held the permits, for them to distribute. You can probably guess what happened next: Many fishermen didn't get any money at all, and because their profession was essentially illegal anyway, they kept hunting totoabas, sometimes encouraged—and equipped—by their bosses.
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Sea Shepherd, a conservation nonprofit, dispatched several decommissioned US Coast Guard cutters to San Felipe to pull up nets, but the crews were periodically harassed, attacked, and even shot at by fishermen while the Mexican navy stood by. On San Felipe's promenade, fishing leaders burned a skiff in effigy. They emblazoned the names of their opponents on the hull, narco-banner style.
The vaquita's foes remain as entrenched as always. In late 2018, a few months before the United Nations announced that a million plants and animals face extinction this century, I went to San Felipe in search of the answer to a simple question: How many fishermen had been arrested for illegal gill-netting? A well-dressed junior officer at the local police station—a stark little building on the outskirts of town—phoned his boss, then told me the local army base could help. A guard at the gate there told me to go to the navy base, where a media person told me to email the general-inquiries inbox in Mexico City. When I returned to the police station, the same officer kindly led me to the city administration building to talk to a municipal delegate—the man I should have asked all along, apparently. He told me to talk to the navy.
In my many conversations with Taylor, she had repeated a kind of mantra: “People are always looking for excuses not to do the hard thing.”
A few weeks after Taylor returned from the failed captivity attempt, Phillip Morin came into her office at the Southwest Fisheries Science Center and sat down. A vaquita plush animal lay on her desk, and vaquita portraits dotted the walls. They matched the style of those in Rojas-Bracho's house in Ensenada; Taylor had painted them all herself. Light streamed in from a large picture window overlooking the Pacific Ocean just across the street, but the mood in the room was heavy. “We waited too long with the vaquita,” Taylor said to Morin. “We should have started this process when there were 600 left.”
Morin announced that he had heard back from the San Diego Frozen Zoo with good news: The fresh vaquita samples were viable, and they were busy growing lots of cells. In the run-up to the captivity expedition, he and Taylor had arranged to have the vaquita genome mapped, using samples from corpses found rotting on the beach or floating in the water. The genetic material was half decayed by the time it was catalogued, like a jumbled-up and incomplete pile of puzzle pieces. Still, they hoped it would help them maintain a healthy gene pool as they took more vaquitas into captivity. Now, using the fresh cells, they'd be able to assemble what is known as a reference genome—a complete, high-quality snapshot of all the porpoise's chromosomes. They could finally put together the picture on the puzzle box. Yet with captivity no longer an option, they asked each other: What else could they do with it?
The answer may come from a burgeoning wing of ecology known as conservation genomics. By using the vaquita's DNA data as a yardstick, scientists can gauge whether other animals whose populations are declining—animals they may know less about—are in danger of inbreeding. If the data suggests, as it does with the vaquita, that a species' population has been stable over time and there is little variation within its genome, it's probably at very low risk. If, on the other hand, the genetic variation is high, then the risk might be too.
By cross-referencing the genomes in this way, scientists can quickly assess the most urgent threats an animal faces: If inbreeding isn't the biggest problem, then maybe poaching or habitat loss is. They can also determine whether the animal should be taken into captivity, and if so, how many individuals would be enough. Genomics can shortcut years of field research—which, with a million species on the line, we surely don't have time for. It lacks the simplicity of the 50/500 rule, but according to Oliver Ryder, cofounder of the San Diego Frozen Zoo and keeper of what might someday be the only living remains of vaquitas on earth, it is already paying dividends.
Ryder is a bit like the godfather of vaquita genetics. Rojas-Bracho worked on mitochondrial DNA in his lab; Morin spent time there as a grad student. Ryder also helped resurrect the California condor, and he is steadily inching toward resurrecting the nearly extinct northern white rhino. He cited several instances in which scientists have used genomics to determine whether to intervene. Mountain gorillas, for instance, are something like the terrestrial counterparts to vaquitas. Their numbers are far below those of western lowlands gorillas, and their genome suggests they're far more inbred than their relatives, yet they have far fewer harmful mutations. This suggests that mountain gorillas' population can still recover if their other risk factors are solved. The same is true of Europe's Marsican brown bear. “What that means is that we're less likely to intervene precipitously—that we have more tools for making these judgments,” Ryder explained. Whether or not the vaquita has a place aboard the ark, in other words, its frozen cells could secure spots for other species.
But having those cells on hand inevitably raises a far-out question: What about just de-extincting the vaquita? Can't we try to genetically engineer the porpoise back into existence? Taylor was quick to shoot down the idea. “It is complete science fiction, resurrecting the species,” she said. For one thing, the only chromosomes she and her colleagues currently have are from a female, and to breed offspring they'd need a male. Then there's rearing the calf, which presents numerous Gordian knots: Without a mother, how do you teach it to communicate? To hunt? To evade sharks? It's hard enough reintroducing land animals like wolves or black-footed ferrets, which produce litters. Imagine doing it for an aquatic mammal that produces a single calf every year.
After the captivity attempt, Taylor had given up making porpoise portraits. “It's basically therapy, and painting vaquitas is not making me a happy person these days,” she told me last summer. But she mentioned an upcoming survey that would include an attempt, via crossbow, to get a tiny biopsy from a male. Why, I asked? Her face broke into a mischievous smile. “Science fiction,” she said.
About 12 nautical miles off the coast of San Felipe, on a bright morning last October, the best animal finders in the world were looking out across the water through 2-foot-long military-grade binoculars, anxiously scanning for vaquitas. Taylor and Rojas-Bracho were aboard the Narval, a repurposed sightseeing boat, and in close radio contact with a nearby Sea Shepherd cutter. They hoped to spot a dorsal fin—a 12-inch-tall black triangle among a billion zillion little blue triangles.
“Oh my God, vaquita! Vaquita!” a spotter called out. On the flying bridge a few feet away, Taylor, wearing a sun-flap hat and a headset like a football coach's over her short gray hair, calmly radioed Rojas-Bracho on the bridge. Both boats stopped. “They should be point-eight miles off your bow,” Taylor told the Sea Shepherd crew.
The Narval's diesel engine quit rumbling. No one said a word; if anyone had to move, they tiptoed. The aroma of Marlboro smoke wafted by. The boat rocked gently. Five minutes later, a voice on the radio: Spotters on the Sea Shepherd boat had identified two vaquitas—a mother and calf! Taylor dispatched a dinghy, and within two minutes it slowly motored off, with a photographer and a scientist armed with a crossbow. The dinghy stalked quietly into the area, but the hunt proved fruitless. Ten minutes went by, and gradually everyone acknowledged that the vaquitas had simply vanished once again.
By the end of the two-week survey, Taylor and Rojas-Bracho's team had spotted nine vaquitas, three of which were fat, healthy-looking calves. As always, though, the good news was tempered by bad: Fishermen were still working in the area, sometimes extremely close to the vaquita sightings. There were as many nets in the water as ever.
Late one afternoon, when the Narval was in dock and the sun was setting over the craggy desert mountains behind San Felipe, I joined Taylor on the flying bridge. She explained that her team identifies individual vaquitas by the nicks and scarring they get on their dorsal fins from gill nets. The female they'd captured had the markings. But another they'd pursued earlier had evaded their nets. They'd never caught it. “It was the first time I understood that the 1 percent left is not a random assortment,” she said, leaning against a railing. “It gives you a little bit more hope that they can make it if they are the cautious type and they are teaching their calves to be cautious as well.”
As rays of hope go, survival of the fittest seems like a faint one. By the time these geneticists unlock the story of the vaquita through its genome, the porpoise might live on only in a test tube, gone forever from the waters it settled long ago. Then again, when people won't do the hard thing, sometimes nature will.
ADAM ELDER is a writer in San Diego.
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