The drone is hovering above the Amazon river, but its battery is running low. André Coelho, the chief pilot, steers it back to safety with skills perfected by playing video games. Long hours practising on Need for Speed have become a surprising asset in the effort to conserve the dolphins that live in the river.

Marcelo Oliveira, a conservation specialist at WWF Brazil, stands on the bow of the boat with arms aloft. He plucks the white drone from the air, changes the battery, and swiftly sends it back into the sky.

Both species of Amazon river dolphin are categorised as ‘data deficient’ on the IUCN list making it harder to gain protection for them. Photograph: Alamy

Later, scientists will examine the video it has recorded for signs of the two species of dolphins that inhabit the river: the pink and bulbous boto, and the smaller, prettier tucuxi. Exactly how many live in the basin is a mystery. Some studies have tentatively pointed to a decline of the pink dolphins in specific areas of the Amazon, but both species of dolphins are categorised by the International Union for Conservation of Nature as “data deficient”.

Scientists at the Mamirauá Institute, based in the remote Amazonian town of Tefé, have teamed up with WWF Brazil to use drones to collect aerial footage of the river. These videos will help plug a data gap; conservationists have found it is difficult to argue in favour of a species you know nothing about.

“We need to base everything – all the decisions and everything we push – on hard data and hard science,” says Miriam Marmontel, a scientist at the Mamirauá Institute, when we speak on the institute’s floating base that evening. She believes there are at least 10,000 botos out there, but that the real number could be as high as 100,000.

“This data builds slowly. It’s scary because there’s a lot of work going into it and you can’t really say anything. We need to focus on what’s really critical to help us get to a real status that can influence policy. We need numbers, we need information on mortality and reproduction. Those are crucial.”



Marcelo Oliveira waits to catch the returning drone. Photograph: Sophie Yeo

Marmontel’s biggest concern is that dolphins are becoming entangled in the nets of local fishermen. She’s found bodies to prove it – pink corpses floating in the lake with scars caused by gill nets. Scientists have also raised the alarm over fishermen killing botos as bait for piracatinga, a large carrion-eating fish popular in Colombia.

Mercury contamination from goldmining is also a concern, as is the Brazilian government’s plan to build dams throughout the Amazon basin. According to a recent paper published in Nature, 140 dams have already been built or are under construction, with plans for a further 428. These would be impassable obstacles to dolphins, isolating communities and decreasing genetic diversity. “The threats are there. They’re just under construction,” says Oliveira.

The scientists want to use the information they collect to persuade the IUCN to list the boto and the tucuxi as either “vulnerable” or “endangered”. Funding agencies and governments want urgency and evidence: without an IUCN categorisation, it is difficult to raise the money for protection measures.

Counting dolphins using the drone footage is more accurate than counting from a boat. Photograph: João Cunha/Mamirauá Institute/WWF

They hope their drone monitoring will do the trick. During three trips to the Amazon last year, the team has recorded about 70 samples that will contribute to a more accurate estimate of dolphin populations in the Amazon basin.

When the team reaches land, they will count the dolphins by examining video footage – a method cheaper, more efficient, and more accurate than counting manually from a boat. To persuade IUCN to update the dolphins’ status, scientists across the South American region are also planning to use satellite tagging, thermal monitoring and ultrasound.

Early next year, researchers from Colombia, Bolivia, Peru and Ecuador will meet to combine their monitoring efforts, creating the most accurate database on Amazon river dolphins to date. They plan to present it to the IUCN by the end of 2018.

Despite their efforts, the database will still only cover a tiny proportion of the enormous region. Whether the IUCN finds this data sufficient to upgrade the status of the dolphin remains to be seen.