By Teresa Tomassoni, Inside Climate News
Marine biologist Fernando Trujillo has spent a lifetime working with the endangered creatures, which offer a window into the health of the rivers in which they swim.
VICHADA, Colombia—From the bow of a canoe-shaped motor boat called a bongo, marine biologist Fernando Trujillo aimed his zoom lens toward a stretch of muddied river water flowing past an ochre-colored sandbank and dense riparian forest where jaguars, wild boar and anacondas roam.
Not far from shore, a dolphin’s long needle-like snout and bulbous head pierced the water’s surface. Trujillo pressed his camera’s shutter button, attempting to capture an image before the dolphin dove out of sight. Nearby, another emerged, the arch of its back and blunted dorsal fin gliding seamlessly through the water as two others waved their rosy hued tail fins, or flukes.
They might be mating, said Trujillo, scientific director and co-founder of the Fundación Omacha (or Omacha Foundation in English), an environmental nonprofit formed to conserve freshwater dolphins, manatees and other aquatic life and their ecosystems. They could also be hunting, he said. Pink river dolphins, as they are commonly called, are skilled at navigating murky shallows and flushing out their prey from hiding amidst tree roots and other obstacles.
Either way, the animals were blushing. The more active they are, the more pink they appear. Otherwise, here in the Orinoco River, they are mostly gray.
Slowly, the boat approached the sandbank and parked. Trujillo continued to watch the animals intently. As he followed the dolphins’ movements, he also looked to a group of fishermen idling quietly in their narrow bongo just offshore, preparing to unfurl their net around the animals when the moment was right.
Trujillo had hired the fishermen from Venezuela—which, like Colombia, shared a border with the Orinoco River—to help capture and release river dolphins during a week-long scientific expedition he was leading in partnership with his colleague, María Jimena Valderrama Avella, a veterinarian who specializes in wildlife medicine.
Securing the large, lithe aquatic mammals takes skill and strength. And they aren’t always easy to find.
River dolphins are some of the most endangered cetaceans in the world, according to the International Union for Conservation of Nature’s Red List of Threatened Species.
It was early February and Trujillo and Valderrama Avella had motored upriver from their base camp on the banks of the Orinoco, along with a group of other veterinarians, early career ecologists and biologists who were part of their expedition team. There were seven of them in total, and all wore closed-toed water shoes, swim leggings and matching long-sleeved rash guard shirts depicting an illustration of a leaping rose-colored dolphin.
They wanted to document any visible scars, injuries or other abnormalities and collect blood and tissue samples from the blubbery animals to test for genetics and any diseases or pollutants they might have been exposed to.
“Dolphins can be good sentinels of the health of the rivers,” Trujillo said. “They are a good species to study and understand how the conditions of the rivers can affect the health of biodiversity, but not only biodiversity—also humans.”
They were particularly interested in testing for mercury, a naturally occurring element found in the Earth’s crust and soils that becomes highly toxic when it’s released into the air or waterways, mostly through human activity such as deforestation, wildfires and mining.
The World Health Organization considers mercury to be one of the 10 most dangerous chemicals that pose a threat to people, especially those who eat fish that contain the compound. The chemical has been linked to neurological and kidney damage, skin irritations and birth defects. In marine mammals, mercury poisoning can cause brain damage, reproductive health issues, behavioral changes and death.
Since 2013, Trujillo and his team have been testing mercury levels in river dolphins to obtain critical data they say can be used not only to protect the endangered animals, but also the rivers they live in and the people who depend on them.
“We are using the dolphins as ambassadors of the conservation of the rivers,” said Trujillo, 57, who has spent more than 35 years working with fisherfolk, Indigenous communities, officials and scientists to save the animals and their habitat. Last year, he was named the 2024 Rolex National Geographic Explorer of the Year for his lifelong commitment to conservation throughout the Amazon and Orinoco river basins.
Several million people depend on the Orinoco—the third-largest river in South America—for food, drinking water, fishing, tourism and transport. For more than 1,300 miles, the river flows from the high slopes of the Sierra Parima mountains of Venezuela and Brazil, down through dense forests and vast stretches of low-lying grasslands in Colombia and Venezuela, emptying eventually into the Atlantic Ocean just east of the Caribbean island nation Trinidad and Tobago. “Rivers are the veins to the ocean,” Trujillo said.
And protecting them is his priority.
About 60 miles downstream of where the expedition team was trying to capture dolphins was the Orinoco Mining Arc, an area in Venezuela bigger than the size of Portugal that is a hub for illegal gold mining operations and a likely source of most of the mercury that enters the Orinoco, according to Trujillo.
Miners use mercury to bind gold flakes together, separating them from mud and other sediments. In the process, polluted wastewater enters the river and other waterways, where bacteria convert it into its most toxic form, called methylmercury. It’s then absorbed by fish through their gills, which continues to accumulate as smaller fish are eaten by bigger fish and those fish are consumed by both humans and dolphins.
Like sharks in the ocean, dolphins are some of the top predators in their riverine environments, consuming and controlling fish populations as they traverse large stretches of rivers, tributaries and lagoons throughout their long life spans. Without them, Trujillo said, “you start to have a loss of equilibrium of all the species. We can’t afford to lose them.”
But their populations are dwindling. Since the 1980s, river dolphins around the world have declined by more than 70 percent, according to the World Wide Fund for Nature. They face a barrage of threats from pollution to entanglement in fishing gear and overfishing, which has depleted the animals’ food supply, not only in the Orinoco and the Amazon, but also the Ganges, Indus, Irrawaddy and Yangtze rivers.
Hydroelectric dams and other large infrastructure projects pose additional threats to the animals by cutting off migratory pathways the dolphins depend on to move between breeding or feeding grounds. In 2007, the baiji dolphin that lived in China’s Yangtze River was declared extinct as a result of all these hazards. It is believed to be the first dolphin species to become extinct as a result of human activity. Today, there are six species of freshwater dolphins left globally.
And then there’s climate change. In 2023, record-high water temperatures in the Amazon and extreme drought killed more than 300 river dolphins in Brazil.
“If the river is gone, the dolphins, the otters, the manatees, the fish, everything is gone,” said Trujillo, who helped to create a first-of-its-kind global declaration for the protection of river dolphins. The non-legally binding accord calls for the establishment of protected river areas to conserve dolphin habitat and encourages transboundary collaboration amongst countries that share waterways used by the animals to ensure they can move freely without harm. In 2023, representatives from 10 countries in South America and Asia signed the agreement in Colombia’s capital, Bogotá.
The Man Who Became a Dolphin
As an undergraduate studying marine biology in the mid-1980s in his native Bogotá, Trujillo envisioned his future self working with sharks or whales. But after meeting with the renowned French oceanographer Jacques Cousteau at a conference, he changed his mind. When he asked Cousteau what he should focus on, the response surprised him. “Dauphins,” Trujillo recalled him saying in French, referring to the freshwater cetaceans living in the Amazon. Cousteau told him, “Nobody is studying the dolphins there.”
Trujillo began talking with his professors about the idea. They were not enthusiastic. “They said, ‘No, it’s impossible. It’s very expensive. It’s very difficult to go to the Amazon.’”
But in 1987, at 19, he made his way to a small town called Puerto Nariño, located right on the Amazon River, with a few fellow students. They found a place to stay in a fishermen’s residence. It was the only place they could afford.
Immediately, Trujillo felt at home. “I remember the next day. That was fantastic. Beautiful town, beautiful people, very friendly. And we started to look for the dolphins,” he said. “It was something magic. Because you know you are in the forest. You are expecting parrots, jaguars, caimans, and suddenly you have a pink river dolphin jumping or a gray dolphin jumping as well. So I was amazed.”
Over the next few years Trujillo returned to Puerto Nariño to learn as much as he could from the local Indigenous Tikuna, Cocama and Yagua peoples, who had lived with the pink river dolphins—also known as Amazon river dolphins—for generations. Many spoke of myths and legends their ancestors had told them about the animals, known locally as “bufeos.”
The Tikuna people started calling Trujillo “Omacha.” At first he thought there was some misunderstanding about his real name. He would try to clarify and say, “No, I’m Fernando. It’s not Omacha.” But the name stuck. One day he asked if they were making fun of him, or if the name meant something bad. “They say, ‘No, no, no. On the contrary, we believe you are a dolphin that became human to protect the dolphins,’” he said. That is what Omacha means in the Tikuna language, they told him.
In 1993, when Trujillo co-founded the Omacha Foundation, he named it not after himself, he said, but for the deeper meaning of the word. “What it means to be in the skin of an animal, to be buried in deep connection with the species, with the territory.”
The Tikuna had warned him that they did not trust scientists who visited their territory, spending a week here and there collecting information and never returning after winning accolades for their findings the Indigenous people provided. But perhaps Trujillo was different. “Yes, you’re right,” Trujillo said he told them. “I need to stay here. We need to build something here.” At 24, he built a field station in Puerto Nariño that began hosting students and research scientists, as it continues to do.
Over the years, Trujillo worked closely with local communities, especially fishermen, to alleviate conflicts they had with the dolphins. Some fishermen felt the animals were jeopardizing their livelihoods by stealing fish from their nets or biting chunks from their fresh catch with their sharp teeth. The dolphins have around 100 teeth and are the only freshwater dolphin species to have molars that are used to chew their prey.
In response, Trujillo helped set up a co-op run by the fishermen’s wives and other female relatives that made nutritious patties out of the fish that had been damaged. He also helped develop economic alternatives to fishing such as sustainable “dolphin watching tours” and selling artisan crafts.
Later on he tried to put an end to the killing of dolphins for bait. Throughout the Amazon and the Orinoco River basins, fishermen have historically used dolphin flesh to catch vulture catfish, known locally as “piracatinga.” Not only was the catfish industry killing dolphins, but it was also poisoning people. The catfish was known to contain dangerous levels of mercury, and Trujillo thought the people consuming them had a right to know.
In 2015, Trujillo began calling upon Colombian government officials to ban the sale and trade of the piracatinga. Two years later they did. Soon after, however, he said a representative from the U.S. embassy sent him a message: Catfish traders had hired hitmen to kill him.
For months he wore a bulletproof vest. He stopped bringing his two daughters to the Amazon for several years, for fear of their lives being threatened, too.
Meanwhile, he continued to expand his research and advocacy throughout the region, including along the Orinoco River, where he had begun monitoring dolphins in 1995 at the same time that he was working in Puerto Nariño. The area holds precious memories from Trujillo’s childhood. When he was 5 years old he traveled with his family to vacation in Puerto Carreño, a port city located on the Orinoco River in the eastern part of Colombia in Vichada.
He remembers adults warning him to take precautions when playing in the river with his brothers. They told him to throw pebbles into the water to scare away the piranhas and use a walking stick to ward off stingrays. One time while swimming, he heard voices yelling for the children to get out of the water. “Toninas! Toninas!”
He later learned tonina was the local word for river dolphin. Little did he know then that he would spend much of his later life running toward these animals and worrying when he couldn’t find them.
The Capture
In February, when Trujillo and his team spotted the small group of dolphins that were possibly hunting or mating, he was relieved. He estimates there are fewer than 3,000 dolphins living in the Orinoco.
They had spent hours looking for them earlier that day while traversing gentle rapids flowing in between mountainous rocks estimated to be around 900 million years old. One of them, Trujillo pointed out, resembled the profile of a manatee. In between some of the boulders, they spotted a group of giant otters poking their curious heads out of the water, but no dolphins.
“We covered a very huge area looking for dolphins, and we saw very few,” he said.
It could be that the dolphins had moved to other parts of the river to follow migrating fish. But he was worried because he also knew people were hunting and selling dolphin meat just across the Colombian border in Venezuela in illegal gold mining camps.
Since COVID-19, there had also been an uptick in the killing and harvesting of dolphins to make tinctures from their blubber, touted falsely as having healing properties for respiratory illnesses.
Last year, there were 17 documented deaths of dolphins in the Orinoco River. They had either drowned after becoming entangled in fishing gear or been killed intentionally, according to Ruben Dario Grisales Valencia, a Colombian boat captain who was driving the expedition team around on the bongo as they looked for dolphins. He had verified the deaths himself through in-person observations, photos or other reliable sources, he said.
Now, as Trujillo tried to photograph the animals with his zoom lens, Grisales Valencia said he’d just heard from the fishermen on his radio. “They’re going to throw the nets!” he told the team. “Get ready!”
As he steered the boat towards the sandbank and parked, several members of the group began setting up a tent and their makeshift lab in the muddy sand where they would perform the health assessment, assuming they could secure the dolphins.
Trujillo put his camera away, waded into the water up to waist height and began slapping the surface with his hands. The youngest of the fishermen assisting with the capture, a 17 year old from Venezuela, began performing backflips and somersaults in the water. Sometimes the dolphins were curious enough to approach such commotion, said Trujillo, who was both excited and nervous for the moments to come.
Capturing the animals always pained the scientist, who found corralling the wild animals, even temporarily, to be a sacrilege of sorts.
“I hate it,” he said. “It’s a kind of abduction. It’s the first time they feel somebody take them out of the water and they don’t know what is going to happen.”
But he saw it as a necessary evil.
During the capture, the animals’ wellbeing was of utmost importance.
When he heard one of the fishermen’s boat engines begin to rev, he watched as the men aboard speedily cast their 800-foot-long net into the water, forming an arc of a barricade around the dolphins, trapping them between the mesh and the sandbank. One of the men helping with the catch, Jose Maria Rangel Guerrero, made the net out of cotton material so it would not cut into the animals’ rubbery skin like the nets made out of monofilament nylon that some other fisherman used. The holes were also made small enough that none of the dolphins’ body parts could become entangled. Trujillo and other team members then ran and swam towards the perimeter of the net to grab hold and keep it from sinking. Otherwise, the dolphins could escape.
Once the net was in place, the team began walking it to the shore, enclosing the two dolphins they had captured. As the animals swam into the net, Trujillo and others firmly grabbed their heavy heads, bodies and tail fins. It took eight people to carry the largest of the two animals to shore. They would assess it first, holding the other dolphin securely in the water until the bigger one was released.
The Health Assessment
On shore, the team laid the dolphin on a plastic mat underneath the tent to shield it from the sun, and the sopping wet crew members sprung into a flurry of synchronistic actions they’d been assigned.
Valderrama Avella, the vet, plugged her stethoscope into her ears and began listening to the dolphin’s heartbeat as another team member counted the animals’ breaths. More than eight, or less than one, per minute would indicate the animal was too stressed and needed to be released. If the dolphin is uncomfortable or it starts to breathe faster or have tremors, the animals are released immediately, she said.
Valderrama Avella, 30, began working for the Omacha Foundation five years ago after meeting Trujillo at a zoo in Villavicencio, a city about 45 miles outside Bogotá, where she supported its wildlife rehabilitation program. After joining him initially as a volunteer on an expedition in the Amazon to track river dolphin movements by attaching satellite tags to the animals, her life changed, she said.
Since then, she’s continued to work for the foundation, coordinating community education programs and expedition logistics, and more recently overseeing the group’s river dolphin health assessments.
As she continued monitoring the animal’s vitals, four other fishermen and crew held it in place. Trujillo caressed its head and covered its eyes with a damp towel, whispering reassurances to the dolphin as others took measurements of its body, dorsal fin and fluke. At the same time, another vet used an ultrasound to check out its intestinal tract, kidneys, lungs and reproductive organs. The dolphin was an adult male, he said, and showed signs of having a type of pneumonia. Its belly was full of fish.
Every few minutes Trujillo would quietly call for “agua.” And another team member would gently pour water over the dolphin’s body to keep it moist.
Valderrama Avella continued her well-rehearsed routine of extracting blood from a vein on the underside of the dolphin’s tail fin, filling a number of labeled test tubes, which would be sent off to a lab in Bogotá for analysis.
Then she clipped a small tissue sample from the top of the fluke for mercury testing and genetic analysis. Trujillo is convinced that the pink dolphins in the Orinoco may in fact be another subspecies that he would like to see officially recognized some day.
As I documented the hectic series of procedures, he asked me to take photos of the dolphin’s melon-shaped head and beak covered in deep bloody gashes, likely caused by monofilament fishing net, along with other cuts, scars and bruises on the sides of its pink and gray body and flippers, that were probably the result of fights with other male dolphins.
As they finished the assessment, Trujillo moved from his original station at the head to the dolphin’s dorsal fin, where Valderrama Avella applied a numbing spray to the soft cartilage. Trujillo then drilled a small hole through the fin so that Valderrama Avella could attach a satellite tag, which would track the dolphin’s movements. If they knew where the dolphins traveled, they could better advocate for the protection of certain river areas that were important to the animals for breeding or migrating.
The Release
Before releasing the dolphin, they weighed it using a scale hanging from a tree branch. At 300 pounds, it was still smaller than some of the largest pink river dolphins, which can weigh up to 400 pounds and stretch nine feet long.
Lugging the dolphin back to the shoreline took muscle and coordination as the crew shuffled through the muddy sand and carefully lowered the dolphin into the shallows, where it zig-zagged for a moment, got its bearings and disappeared into deeper waters.
With hardly any time to catch their breath, the group quickly celebrated the successful release with hugs and high fives before turning their attention to the second dolphin, repeating the adrenaline-filled procedure. The second dolphin was significantly smaller and without as many scars, but like the first, also showed signs of having pneumonia.
Over the next few days, the group would capture a total of 16 dolphins and assess 11. Some that were captured were too young to assess, Valderamma Vella decided. She didn’t want to stress them. Others escaped.
On Valentine’s Day, they caught four dolphins at the same time and conducted assessments back to back in under 45 minutes. One of the dolphins was pregnant.
A Reason for Hope
That afternoon, Trujillo gathered with his team at their base camp in the Bojonawi Nature Reserve on the banks of the Orinoco. Trujillo had co-founded the nature sanctuary in the 1990s to protect more than 11,000 acres of forest, streams and savannah.
In winter, when the river rises up to 40 feet, these areas become submerged. During this time, dolphins can sometimes be observed swimming amongst the trees and in a hidden lagoon, where they have been known to give birth to their young.
The crew hovered around the vet who had been conducting ultrasounds on the dolphins, Miguel Felipe Ortiz Baez, as he showed them the images he captured during the pregnant female’s assessment. Trujillo swapped his tinted sunglasses for reading glasses and leaned in to look at the grainy shape of the dolphin fetus in utero. It was about 6 inches long and he could vaguely detect the outline of one of its flippers, its melon-shaped head and pointed snout in formation.
“Its lungs and heart look good. It doesn’t show signs of any development problems. It’s healthy,” said Ortiz Baez.
Trujillo smiled, clapped his hands together and turned to his team. “The message of today is hope,” he said. “This gives us hope because it’s one more dolphin. It’s a dolphin that’s going to be born in the Orinoco.”