What’s Killing the Pink River Dolphin?

In the Brazilian Amazon, two veteran scientists are embroiled in a bitter feud over how to protect the endangered mammal.

AT 4 A.M., BEFORE THE SUN STARTED TO RISE over the Amazon rainforest, Veronica Iriarte stepped into her aluminum skiff and started the motor, battling unsuccessfully with a swarm of hungry mosquitoes. She stopped to pick up her assistant, a local named João de Assunção Pontes who lived on the other side of the river, before beginning the 60-kilometer journey into the heart of the jungle. Their destination was a large wooden crate, partially submerged in the water, located near one of the native villages that pepper the riverbanks. She had noted the location of the box the day before. She suspected it contained the corpse of a pink river dolphin, a protected species in Brazil.

They approached the box quietly, hoping not to disturb the still-sleeping fisherman. There were no signs of any dolphins in the crate. Instead, the box was writhing with piracatinga, a carnivorous catfish drawn to the smell of decaying flesh. It’s known in Portuguese as urubu d’água: “water vulture.” If there had once been a dolphin, it was now inside the stomachs of these wriggling fish.

That left Iriarte with only one option. She drew the skiff alongside the crate, grabbed one of the bulging creatures, and began to massage its stomach. In less than a second, it puked up its latest meal. Iriarte gathered the vomit and stored it in ethanol — an undignified resting place for what could be the remains of one of the Amazon’s most mysterious and enchanting creatures.

DURING THE THREE YEARS she spent as an aquatic mammal researcher with the Mamirauá Institute for Sustainable Development in the Amazon, Iriarte made almost 200 trips like this down the river, searching for these fish, and for the remains of butchered dolphins. These piracatinga could provide evidence of crimes committed — genetic sequencing showed that 58 out of 80 samples she collected on these trips contained pink dolphin meat — but they were also the reason for it. Iriarte knew that soon after she left, a fisherman would come and collect this harvest, whereupon these fish would be systematically slaughtered, stored in ice, and shipped to markets in Brazil and Colombia. With one dolphin carcass, an Amazon fisherman can expect to catch enough piracatinga — around a ton of fish — to make up to $1,000 in a single night.

The piracatinga fishery is a fairly new phenomenon in South America. Brazilians have never liked the species, disgusted by its tendency to feast upon rotting flesh — so fish processing plants began operating on the principle that what consumers don’t know won’t hurt them. Using molecular tools, scientists have confirmed that a fictitious fish named “douradinha,” sold everywhere from supermarket chains to street markets, is in fact piracatinga. In Colombia, piracatinga is fraudulently marketed as “capaz,” a popular fish that has been depleted by overfishing.

Piracatinga (Calophysus macropterus) aren’t especially fussy eaters — they have been found eating the livers of rays and the meat of giant anteaters — but they particularly love the fatty blubber of the Amazon’s pink river dolphins (Inia geoffrensis), known locally as boto. Fishermen target the boto, even though it’s been illegal to hunt the aquatic mammal in Brazil since 1967, knowing its stinky flesh guarantees a large harvest.

While the piracatinga fishery began in the mid-1990s, scientists only started to notice the use of dolphin corpses in 2000. Seven years later, 1,600 tons of piracatinga were being caught in Brazil every year, much of it exported to Colombia. In the upper stretches of the Amazon basin, harvest increased by a factor of 27 between 2003 and 2009. The fish doesn’t fetch high prices — with fisherman receiving, at best, a dollar per kilogram, they need to catch large numbers for their business to be profitable. That’s bad news for the Amazon river dolphins. With China’s Yangtze river dolphin declared functionally extinct in 2006, the boto represents an especially poignant frontier for conservationists and aquatic mammal biologists. Yet attempts to monitor and respond to this new threat have led to an increasingly rancorous argument among scientists and conservationists.

IN THE BRAZILIAN AMAZON, there are two uncontested experts on the boto: Vera da Silva and Miriam Marmontel. Both have been working to overcome what, until very recently, was a key obstacle in Amazon dolphin conservation — the fact that, in 2008, the International Union for the Conservation of Nature (IUCN) changed the boto’s status from “vulnerable” to “data deficient,” recognizing that most of the information regarding the dolphin’s population size and the threats it faces were now out-of-date.

This recategorization of the world’s largest freshwater dolphin plunged scientists and campaigners into a no man’s land of conservation. They knew that industrial development and overfishing in the Amazon were thrusting the dolphin into an ever more vulnerable situation — but, without the sense of urgency denoted by the IUCN “endangered” label, they found it difficult to raise the funds to campaign on behalf of the boto, a challenge that has been compounded by a sudden crash in science funding in Brazil (money is probably going to get even more scarce during Bolsonaro’s presidency). The lack of information on the dolphin itself, including the size of the population and its patterns of reproduction and behavior, has also hampered conservation efforts, making it difficult to draw up a plan to save this fragile species.

“This might be a perverse incentive, that we pray for dolphins to be ‘endangered.’ But if we are not able to find funds, how are we going to tackle the problem?” says Marcelo Oliveira, a conservation specialist at World Wildlife Fund, Brazil. “There’s a gap in the information. Are we doing the right stuff? Are we doing enough?”

Vera da Silva has spent more than two decades documenting botos. In the process, she has created the most detailed dataset of Amazon river dolphin populations in existence. Photo Jonne Roriz / AMPA
Vera da Silva has spent more than two decades documenting botos. In the process, she has created the most detailed dataset of Amazon river dolphin populations in existence. Photo Jonne Roriz / AMPA.

Both Marmontel and da Silva have devoted their careers to filling in these gaps. Between them, these two academics have almost eight decades of experience in studying aquatic mammals. Yet the two doctors, who once went to university together, have scarcely spoken to one another for more than 20 years. They have been embroiled in a bitter feud since the 1980s, one that their shared love of the boto has failed to overcome.

Neither can recall, or will admit, the reason for their long-standing dispute. “I just don’t like the way she works,” is all Marmontel offers as explanation. Da Silva suggests that there might have been a “personality clash.” The two have never collaborated, and da Silva refuses to peer review Marmontel’s papers, fearing accusations of bias. Over the years, the two have adopted starkly different attitudes to conservation, and have denounced the other’s approach to science.

While Marmontel has long worked at the intersection of social and environmental issues, da Silva has dedicated more than two decades to the precise enumeration of the population of botos in a small area of the rainforest that partly overlaps with Marmontel’s research area. And while both are dedicated to the study of the Amazon’s aquatic mammals — not just the number of dolphins and manatees in the Amazon’s waterways, but detailed studies of hormone levels, acoustic behavior, and genetics — Marmontel’s research is rooted in her institute’s determination to work with and improve the lives of local communities, while da Silva has focused on creating the longest and most detailed dataset of the Amazon river dolphin populations in existence today.

Marmontel lives in Tefé, a crumbling city in the middle of the Amazon, where she works at the Mamirauá Institute for Sustainable Development — a research body that struggles to retain its employees. Life in this deprived and isolated outpost quickly drives away young biologists. Not Marmontel. She joined the Institute in 1993 after finishing her PhD in Florida, and has stayed there ever since. Throughout the city, her name carries a sense of authority, of permanence: Local people refer to her as “the doctor.” Her office is cluttered with trinkets and postcards, almost all depicting a dolphin or a manatee. She is unquestionably devoted to the Mamirauá Institute’s grand project: the Mamirauá Sustainable Development Reserve.

The creation of this reserve began with one man’s obsession with a rare, scarlet-faced monkey, the uakari, and ended up changing the way Brazil did conservation. In 1983, a young primatologist named José Márcio Ayres set out in an old boat partly paid for by his parents to seek out and study the white uakari, which was once thought to live only in the small portion of the Amazon that would eventually become the Mamirauá Reserve. At that time in Brazil, people and nature were considered incompatible. As protected areas were established throughout the Amazon, native communities who had lived undisturbed for centuries were harassed and forcibly evicted from their land. For example, when the 400,000-hectare Ecological Reserve of Trombetas was established in 1979 in neighboring Pará state, the quilombo communities — who descended from escaped African slaves — were no longer allowed to hunt, fish, or plant crops. The country’s environment ministry, helped by the federal police, forcibly removed their tools.

On the strength of Ayres’ work on the uakari, more than a million hectares of floodplain forests and wetlands were designated as the Mamirauá Ecological Station in 1990 — a strict status that forbade any form of human habitation. But Ayres had also recognized the value of the local people who inhabited this rich floodplain, and in 1996, he persuaded the governor of Amazonas state to issue a decree establishing the area as a “Sustainable Development Reserve.” This was a new designation that combined the needs of both people and nature, harnessing the presence of native communities as a tool to regulate and defend the Amazon’s natural resources. Ever since then, the Mamirauá Institute has overseen a series of management programs designed for long-term conservation in this unique reserve, both preserving the ecosystem and improving the quality of life of its human residents. This is the context in which Marmontel has worked for almost the entirety of her career.

Vera da Silva’s career, on the other hand, has been devoted to meticulous data collection throughout this same reserve. Most of the year, she lives in Manaus, the capital of Amazonas state. A city built on the rubber boom of the 1800s, it is now the home of the National Institute of Amazonian Research, where da Silva has worked since 1981. But every year since 1994, she’s ventured into the field, living out of her floating laboratory, the Red Dolphin Raft, from which she marks and tracks the individual dolphins that live in and around the Mamirauá Reserve, accumulating an unparalleled dataset outlining their movements and behavior. Over the years, she and her team have collated hundreds of surveys, and observed the lives — and deaths — of thousands of dolphins.

The threat of the piracatinga fishery, and its impact on the dolphins, is the subject of the latest disagreement between the two scientists. Da Silva believes the targeted hunt of the species has led to the greatest pressure on the boto since Europeans first came to the Amazon. But Marmontel thinks it’s a small problem that has been dramatically overblown, thrust into public view by a crude and disingenuous turn of the media’s wandering eye.

There is little love lost between Amazon communities and the pink river dolphin, which many believe is a shapeshifter.

At its heart, this conflict between the two scientists over threats to the boto is not about criminals and killers, but about the steady encroachment of twenty-first century Brazil into the remote outposts of the Amazon. It’s the story of how this forest, once a bountiful provider, no longer meets the desires of those who reside beneath its canopy and alongside its river. That dolphin hunting occurs even in the Mamirauá Reserve, a pioneer in uniting social development with environmental protection, only illustrates the difficulties and importance of the task begun by the young Márcio Ayres almost three decades ago.

FOR THOSE FAMILIAR ONLY with the grey, seemingly smiling dolphins of the ocean, the boto will come as a shock — and not because of its pale pink skin. This dolphin, which can grow up to 9 feet in length and weigh some 300 pounds, has an unusually bulbous head that morphs awkwardly into a sharp and rather menacing-looking snout, lined with up to 34 pairs of teeth. It has no dorsal fin; instead, its thickset back arches into a graceless hump.

While it may have an ungainly appearance, the boto is a protected species in Brazil. Yet the dolphin has faced a variety of challenges to its survival over the years. There is little love lost between the native communities of the Amazon and this pink creature, which many people believe to possess powers of enchantment and shapeshifting, allowing it to seduce women, put spells on people, and lure the objects of their desire to an underwater city. Local people call their pink pigmentation “the devil’s color,” and tell stories of mysterious visitors to their villages who attend parties, father children, and steal spirits, before leaping back into the river. “One sees many children of the Boto in these parts,” one local told Candace Slater, an American professor of Spanish and Portuguese, who visited the Amazon four times between 1988 and 1992 to explore such myths. This reputation, alongside the perception that dolphins compete for fish and damage nets, means fishermen are often purposely aggressive, and are happy to let entangled dolphins die in their gillnets.

The dolphins face many other threats, including fragmentation of the Amazon river by hydroelectric dams, river pollution from mining and oil and gas drilling activities, and industrial and agricultural runoff. Yet, according to da Silva, none of these issues are as serious as the targeted hunt of dolphins for bait.

“I started counting dolphins in 1994, and till 2000, more or less, you saw a decline in the curve, but very small. It was somehow, let’s say, sustainable,” she says. “But then, when they started killing botos [for piracatinga bait], then we have this extreme decline, and it’s very obvious. Of course, the number of [fishing] nets [the dolphins get accidentally trapped in] increased, human population in the Amazon increased, the demand for fish increased, but nothing so dramatic as the direct killing of botos.”

Measuring the exact number of dolphin deaths is difficult, as the impact of the industry is spread unevenly across the Amazon basin. Making any kind of estimate of the total boto population in the basin is near impossible. The dolphins roam the Amazon waterways freely, making use of the regions’ wide rivers, flooded forests, and oxbow lakes, and confounding scientists’ attempts to keep track of individuals. The traditional method of counting dolphins from a boat, requiring binoculars and a capacity for fierce attention, is ill-suited to the meandering nature of the river, where the horizon is a moving target over which the boto could vanish at any time. It’s also physically challenging — hours spent hunched in a small canoe, ceaselessly scanning the water for signs of this elusive creature, in the heat of the Brazilian sun, take their toll on the body.

But years of careful counting in the Mamirauá Reserve has enabled da Silva to make an estimate of the population trends for this area at least. She believes the dolphin numbers in the area have dropped by 50 percent over the last decade. When she first started monitoring dolphin numbers more than 20 years ago, da Silva and her assistants would see up to 138 dolphins per trip. But around 2000, when scientists started noticing the dolphin corpses, numbers dropped dramatically. They rarely saw more than 50 dolphins per trip. Da Silva published these results in the journal PLOS One in 2018. The actual decline, she wrote, may be higher, considering that the quiet, protected waters of the Mamirauá Reserve could be attracting dolphins from other regions. Two decades of field trips appear to have finally paid off. Last November, the IUCN revised the status of Inia geoffrensis to “endangered,” based largely upon da Silva’s assiduous data collection over the past 25 years.

In November 2018, the IUCN revised Inia geoffrensis’ status from “data deficient” to “endangered.”

IUCN officials believe that if the declines that da Silva has observed in the reserve became the norm throughout the Amazon, the response required would be even more urgent. “When you look at the Amazon system in Colombia, Venezuela, and even Bolivia — in most of these areas, they’re certainly in worse shape than ‘least concern,’ and worse than ‘vulnerable’ in most of those areas. So settling on ‘endangered’ is defensible,” says Randall Reeves, chair of the IUCN’s Cetacean Specialist Group, who was involved in assessing the dolphin’s status. “The question is whether we should say more than that, like ‘critically endangered.’ I personally don’t think that would have been a good idea, because of total numbers and its extensive range.” But the situation in the Mamirauá Reserve itself could be worse, he adds. “If it were down to the question of the central Amazon and Brazil, ‘critically endangered’ would be simple, that would be the case.”

In other words, unless conservation actions are taken quickly, the Amazon’s mysterious shapeshifter may have a dark future ahead, both in the Mamirauá Reserve and beyond.

COLLECITNG PHYSICAL EVIDENCE of dolphin hunts remains a challenge, with efforts stymied by scavengers, decomposition, and currents. Yet, until she can see the bodies in the morgue, so to speak, Marmontel is skeptical about the supposed impact of the piracatinga fishery on dolphins. She believes that there are at least 10,000 botos out there, but that the real number could be as high as 100,000, and that the IUCN should list the species as “vulnerable.” The biggest challenge to the species, she believes, is entanglement in fishermen’s nets.

She also believes that fishermen usually use caiman over dolphins as bait for piracatinga, and she accuses da Silva of distorting the data — in particular, of over-attributing dolphin disappearances to hunters — in an attempt to court the media. “I think she saw a chance in that situation of getting a lot of attention not only to her, which I think was one of the points, but to the dolphins and making them really endangered, really threatened — dying, bloody stuff,” says Marmontel. “A good scientist wouldn’t do that. You have to be true to what’s happening.”

Marmontel was particularly enraged by the filming of a dolphin hunt that took place in the Mamirauá Reserve. This short but gruesome clip, arranged with the help of da Silva and her students, showed a fetus being ripped from the womb of a boto after a fishing community was paid to demonstrate a hunt. The video aired on Fantástico, a popular Sunday show in Brazil, in July 2014, and shocked the nation. Alerted to the footage days before it was due to air, the Brazilian government finalized a moratorium on the fishing and marketing of piracatinga, which had been languishing unsigned, banning the practice until January 2020. The move cut off many riverine families who depended on piracatinga fishing for their key source of income. Some claimed to have even faced death threats from others in the area who blamed them for the ban.

Marmontel is also frustrated by what she perceives as a side effect of da Silva’s research: the tarnishing of the reserve’s reputation. It’s easy to see why she might have taken this personally, given that much of the work of the Mamirauá Reserve is rooted in improving the lives of river dwellers in tandem with the natural environment. In the case of another overexploited fish species — the enormous, air-breathing pirarucu (Arapaima gigas) — scientists formed alliances with local people to create protected areas and management plans, preserving both fish stocks and the income of the fishermen. Similarly, researchers have now set up a community-based management program for the reserve’s caiman. If humans are killing dolphins in the reserve, it represents a dangerous imbalance in the task that the Mamirauá Institute has set itself: to forge harmony between humans and nature in a remote outpost of a nonetheless modern world.

“It really gets me, because they pointed at us,” Marmontel says. “They’re telling the world Mamirauá is killing dolphins … We documented it, we figured it out in 2000, but it’s not only there. But they point as if we were the culprits and we were stimulating it or whatever.”

Miriam Marmontel has dedicated her career to working at the intersection of conservation and sustainable development in the Amazon. She doesn’t think that hunting them for bait has been a major factor in the decline of the pink river dolphin. Photo Amanda Lélis/WWF, Brasil
Miriam Marmontel has dedicated her career to working at the intersection of conservation and sustainable development in the Amazon. She doesn’t think that hunting them for bait has been a major factor in the decline of the pink river dolphin. Photo Amanda Lélis / WWF Brasil.

Da Silva, however, has no qualms about how the fishermen were treated during the filming, and supports the video as the most effective way to inspire outrage and get the government to take action. “It’s there, still happening, and the guys are professionals; they know exactly what they are doing,” she says. “This community, I will tell you, they were happy to participate in the program. They wanted to be on TV. The decision to cover their faces was ours.”

And just as Marmontel questions her data, da Silva questions whether Marmontel might be downplaying the hunting issue in an attempt to protect the reputation of the Mamirauá Reserve, as well as those who reside in it. “Not a good attitude for conservation,” she says.

Interestingly, Marmontel’s own student, Veronica Iriarte, agrees with da Silva on this matter. It is Iriarte’s study involving fish vomit that Marmontel cites when arguing that the fishermen prefer using caiman meat as bait — only 31 percent of the samples Iriarte collected contained dolphin, the rest contained caiman. Yet while Marmontel uses these numbers to dismiss the threat of the piracatinga industry to dolphins, Iriarte sees in them a crisis that is real and serious. “I found a lot of [dolphin] bones,” she says. “People were doing this everywhere.” Iriarte says that the Mamirauá Institute did not appear to support her work, asking her to change her project during its third year, and refusing to upload her paper onto the Institute’s webpage. “They didn’t want to know this was happening. I became disappointed with Miriam and I quit the job,” says Iriarte, who now works for the Fisheries Department of the Falkland Islands.

Other cetacean experts suggest various reasons for the disparity in da Silva’s and Marmontel’s assessment of the severity of the threat. “The divergence in opinion is likely a result of difference in the observed decline of botos in areas that they monitor, which only partially overlap,” Alex Zerbini and Pedro Fruet, cetacean experts at the US National Oceanic and Atmospheric Administration and Australia’s Flinders University respectively, wrote in an email to the Journal.

None of this means that we should dismiss the work of the Mamirauá Institute. In many ways, its approach to conservation has been genuinely trailblazing. A 2006 report by the International Institute for Environment and Development, a London-based think tank, called Mamirauá Reserve “a pioneer project in that it proposed to safeguard [the area’s high biodiversity value] by working with local people in a positive way, rather than treating them as antagonists of nature.” Such a complete overhaul in Brazil’s attitude towards conservation was never going to be easy: Uniting what used to be considered the separate realms of man and nature meant navigating a complex world of oligarchic local politics and weak rule of law, where conservative policies had typically prevented innovation. Then there was the resistance of the river dwellers themselves. After decades of exploitation by outsiders, local people were mistrustful of newcomers. Some villagers were so hostile to the project that they would cut loose researchers’ moored boats. It took Mamirauá’s scientists five years to win them over.

Yet, something worked: Today, there are 27 Sustainable Development Reserves in Brazil, emulating the model established by young Márcio Ayres. But that doesn’t mean that everything will just continue to work. Ayres died in 2003. The country’s newly elected president has made clear that he is no champion of the environment or of Indigenous rights. And the Amazon itself is changing as are its people. With the outside world encroaching on the forest, it’s natural that these communities might want a bit of it.

“There’s the myth of the noble savage, but we can’t see it like that,” says one former employee of the Mamirauá Institute, who requested anonymity. “Of course, they want to buy things they don’t need. It’s a globalized world, and they want to have the same things as everyone: a cell phone, a computer, so they need money for that.” Sometimes, that money might come from piracatinga fishing. And sometimes, it might involve killing a dolphin.

“I believe that Mamirauá is a good thing … But of course problems can happen, and the way you deal with these problems has to be well-managed. And if you want people there, you have to give them alternatives,” she continues. “I think the purpose of the Reserve is not to say everything is beautiful and perfect, but if they see a problem to try to come up with a solution for that.”

These solutions will not be easy. They will require time and money, but also the emotional labor that comes with sacrificing ideals, with acknowledging that the Amazon rainforest, once verdant and remote, is now a place laced with irrevocable loss: the loss of ancient lifestyles, of monkeys and dolphins, and of the ability of the land itself to provide. Money, technology, and overconsumption are now more visible in the landscape than the rare white uakari. In this complex ecosystem, da Silva and Marmontel have dug their ideological trenches. But just as one researcher’s decision to let the media lure hunters to kill dolphins didn’t account for the genuine vulnerability of the Amazon’s river dwellers, the other’s decision to gloss over these hunters’ roles in the decline of the dolphin ignored how life in the rainforest has changed.

Somewhere between these two trenches, there is a vision for science that prioritizes the survival of both the people and the dolphins of the Amazon. There is still time to find it.

Subscribe Now

For $15 you can get four issues of the magazine, a 50 percent savings off the newsstand rate.