Citizen scientists and fishers confirm the Amazon river dolphin lives in Bolivia's Acre River

The Amazon river dolphin, Inia geoffrensis, has been documented in Bolivia for the first time, the Wildlife Conservation Society (WCS) said on 24 October. Three records from 2025 and 2026 place the species in the Acre River, in the Purús basin in the northern department of Pando, on the border with Brazil.

It started with a citizen science weekend

The first record came on 27 April 2025, during the first time the city of Cobija took part in the City Nature Challenge, a global event in which residents photograph and log wildlife. Two dolphins were seen near the Junín neighborhood. Local fishers supplied the other two records: near Puerto Alto in November 2025, and near the Frontera neighborhood in May 2026.

To check the records, researchers interviewed 34 fishers from San Pedro, Junín and Brisas del Acre between May and June 2026, some with more than 30 years on the river. Their accounts supported the photos and videos. Morales said she hopes the record inspires more people to take part in citizen science. The findings were published in the journal Neotropical Hydrobiology and Aquatic Conservation by the Shimanú Amazon Conservation Program, the Institute of Ecology at Universidad Mayor de San Andrés, Juventud Proactiva de la Amazonia and the WCS Bolivia Program, together with local fishers.

“It was a wonderful surprise for us.” — Ximena Morales, Shimanú Amazon Conservation Program

Not Bolivia's own river dolphin

Bolivia already had a river dolphin, but a different one. Earlier research in the country focused on Inia boliviensis, which lives in the Mamoré and Iténez basins. The Acre River belongs to the wider Amazon system, and the new records point to a river connection between Bolivia and Brazil that dolphins use. Adults weigh 100 to 200 kg depending on age and sex, according to WCS.

“This is an extraordinary discovery,” said Robert Wallace, senior conservation scientist at WCS. He said it shows how much remains to be learned about Bolivia's natural wealth.

A species in steep decline elsewhere

The Amazon river dolphin is listed as Endangered by IUCN. In and near Brazil's Mamirauá Reserve, monthly counts over 22 years showed a “sustained, profound decline,” and a population model projected a 95% loss within 50 years, according to a 2021 study in Oryx by Anthony Martin and Vera da Silva. Drowning in gillnets and hunting for fish bait were the main causes.

The next steps in Bolivia are to estimate how many dolphins use the Acre, how they move and whether they stay year-round, and to protect riverside forests and water quality. Bolivia, Brazil and Peru share the basin, and the researchers want the three countries to share data. In the east of Bolivia, river dolphins are also among the species protected by the new Agua Dulce wildlife reserve in Baures.