Swimming with the piranhas and anacondas below the surface of the Amazon River in Bolivia is a rare species: pink, freshwater dolphins.
These animals, locally known as "bufeos," are an indicator species that scientists say exemplify the overall health of the Amazon -- If they are doing well, then so is the river.
"Nightline" went behind the scenes of a pilot program sponsored by the World Wildlife Fund (WWF) in which a group of local fishermen and scientists track and study the habits of the mammal, which is declining in numbers. The program is part of a larger effort by the WWF to tag fifteen pink dolphins across Bolivia, Colombia and Brazil to study their migration, health and genetics.
Global support to conserve a local species
Local fishermen led the charge along the river to locate the dolphins and set nets to safely capture them. Once the dolphins were caught and brought ashore, the scientists stepped in.
They worked in an assembly line of activities, coordinating to quickly give the dolphin a physical.
Under the shade of a tent, the team hydrated the dolphin to lower its stress levels. The medical mission was led by veterinarian Carla Sanchez to continuously monitor the dolphin's vitals.
To make the effort a success, time was key. As the clock ticked, the researchers measured, weighed the mammal and even checked its teeth. They also administered local anesthesia to numb its tail and then slice a miniscule amount of tissue to test for mercury, toxic substances as well as the dolphin's general health.
Paul van Damme, a biologist and director of the Bolivian nongovernmental organization FaunAgua, WWF's field partner on this mission, believes that conserving the pink dolphin should be a global effort.
"We can conserve the species in a local way with the local people, but I think we need support from the global community," he told "Nightline."
Scientists are not sure what gives these freshwater dolphins their pale pink color but some of the hypotheses include diet and behavior as well as water quality and sunlight exposure. What is certain is that the dolphins turn pinker with age.
Deforestation is one of the biggest man-made threats making this species vulnerable to extinction.
For the dolphins, the run-off of sediments caused by deforestation prevents them from swimming freely. In 2010, 26 dolphins had to be rescued when they got stuck in a shallow river.
"You could think about it like a cork in a wine bottle so that cork blocked up the river and the dolphins were stuck in the river. So less trees, there's more mud getting in," said Jordi Surkin, director of the Amazon Coordination Unit at WWF.
"The big problems facing dolphins in Bolivia and throughout the Amazon are basically the same. There are dams, which are blocking the rivers. There is contamination from mercury, which is mostly coming from small-scale mining," he said.
The other threat facing the mammal is the popularization of dolphin meat as fish bait. While that threat has been minimized in Bolivia where the law protects pink dolphins, the species is more vulnerable in Brazil and Colombia.
Dolphin tagging in the Amazon
"Nightline" joined van Damme's team to get a front-line view of the dolphins' satellite tagging - the last of the five they were tagging.
"You want to know how far they travel, how far the males travel in the river searching for females, searching for a family, searching for food," van Damme said.
Through the pouring rain, the team went ahead with its plan. The fishermen patiently waited to catch a dolphin in their nets and the team's routine immediately began.
As they monitored her heart rate, the scientists established that the pink dolphin was female, but not pregnant. She was nicknamed "Ponchita" and would be the first female dolphin tagged. The team had previously caught and returned a pregnant female dolphin without attaching a tag in order to avoid distressing her.
As they worked, the team's members used few words, speaking in almost a whisper in an effort to keep the dolphin as calm as possible.
After the exam was complete, Ponchita was administered an anesthetic shot and an electric drill, commonly found in garages, bore a hole through the dorsal fin for the tag. Because a dolphin's fin is mostly cartilage, the biologists reassured “Nightline” that the pain was minimal.
But the tracker did not fit the dolphin’s fin so they drilled a second time to adjust the hole. After much effort -- and a little blood – the satellite tag fit. Ponchita was weighed and then set free in the river, splashing the researchers and “Nightline” cameras as she swam away. The team shared applause and high fives.
“It was calm and stable the whole time. It didn’t suffer much stress,” said Sanchez. “It was a good effort, wasn’t it?”
With all their tags successfully deployed into the Amazon, the team paused to congratulate each other and take a group photo. The tagging portion of the work was done but there would eventually be four to six months of data from the satellite tags coming in to their computers to analyze.
“It’s very nice to go to the field and to tag the animals to see them, to see how they behave,” said van Damme. “It’s also exciting to see on the screen where they go.”
He said this information will be an initial step in understanding how to help the pink river dolphins.
“If we reach our ultimate goal to conserve the species and to protect it against threats, that’s our main goal,” he said
Watch the full story on "Nightline" TONIGHT at 12:35 a.m. ET.