COBIJA, BOLIVIA, October 24, 2026—Three records of the Amazon river dolphin (Inia geoffrensis) obtained between 2025 and 2026 provide the first documented evidence of the species in Bolivia, in the Acre River basin in the department of Pando. The discovery, reported in the journal Neotropical Hydrobiology and Aquatic Conservation, expands our knowledge of the distribution of river dolphins in the country and highlights the contributions of citizen science and the knowledge of local fishers.

The discovery is particularly significant because research on river dolphins in Bolivia has previously focused primarily on the Bolivian river dolphin (Inia boliviensis), which occurs in the Mamoré and Iténez river basins. The Acre River, in contrast, forms part of the Purús basin and is connected to the wider Amazon River system, providing suitable conditions for the presence of Inia geoffrensis and new insights into the connectivity of river systems between Bolivia and Brazil.

“It was a wonderful surprise for us, and we immediately recognized the importance of filming and photographing the dolphins for the City Nature Challenge,” said Ximena Morales of the Shimanú Amazon Conservation Program. “This encouraged us to organize ourselves and interview local people, especially fishers. They were already aware of the dolphins and even had additional video footage, allowing us to confirm their presence in the Acre River. We hope this record inspires more people to participate in citizen science initiatives and, above all, helps promote conservation efforts along the Acre River.”

The first record was obtained on April 27, 2025, during Cobija’s first participation in the City Nature Challenge, when two individuals were observed in the Acre River near the Junín neighborhood. Local fishers subsequently contributed two additional records: one near Puerto Alto in November 2025 and another near the Frontera neighborhood in May 2026.

“This is an extraordinary discovery,” said Dr. Robert Wallace, Senior Conservation Scientist at the Wildlife Conservation Society (WCS). “We are talking about a mammal that can weigh between 100 and 200 kg, depending on its age and sex, and which now represents a new species record for Bolivia. It highlights how much we still have to learn about the country’s extraordinary natural wealth and fantastic biodiversity. The fact that the discovery emerged through a global citizen science initiative seems almost poetic, emphasizing the role that all of us can play in science and conservation.”

Between May and June 2026, 34 fishers from San Pedro, Junín and Brisas del Acre were interviewed, some of whom had more than 30 years of fishing experience. Their knowledge of the presence of the dolphins and the frequency of sightings complemented the audiovisual records and provided valuable information about a species that, until now, has been very poorly studied in this part of Bolivia. 

The study was conducted by researchers from the Shimanú Amazon Conservation Program, the Institute of Ecology at the Universidad Mayor de San Andrés (UMSA), Juventud Proactiva de la Amazonia, and the Wildlife Conservation Society (WCS) Bolivia Program, with contributions from local fishers.

Important questions remain unanswered. The researchers note that further studies will be needed to determine the size of the population, understand its movements, and establish whether the dolphins remain in the Acre River throughout different seasons of the year.

Conservation of the Acre River is essential for maintaining habitat for the dolphins and other species that depend on this ecosystem. The study points specifically to protecting riverside forests, maintaining water quality, and preserving the basin’s ecological connectivity. Because the basin is shared by Bolivia, Brazil and Peru, the study also highlights the importance of monitoring, habitat protection, and the exchange of scientific information among the three countries. 

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