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Scientific Classification

Common Name
boto, Amazon River Dolphin, bufeo colorado
Cetacea; more recently Cetartiodactyla
Genus Species
Inia geoffrensis
Three subspecies are currently recognized: I. g. geoffrensis in the Amazon River system of Brazil, Peru, and Ecuador, I. g. boliviensis in Bolivia, and I. g. humboldtiana in the Orinoco basin of Venezuela and Colombia.

Fast Facts

The Boto is a pale pink color and has a rounded head, long snout and a small dorsal fin. They also have a flexible neck, which allows it to sweep its head from left to right.
2 to 3 meters (6.5 to 9.8 ft.)
up to 160 kg (353 lbs.)
Botos feed on a large variety of fishes (over 43 species), generally near the bottom.
Botos occur throughout the Amazon and Orinoco river basins, from the deltas upstream to where impassable rapids, waterfalls, lack of water, and possibly low temperatures block their movement. Three geographic populations have been recognized as subspecies: I. g. geoffrensis in the Amazon basin, except for the Madeira drainage in Bolivia above the Teotonio rapids, I. g. boliviensis in the upper Madeira drainage, and I. g. humboldltiana in the Orinoco basin.
Botos swim into flooded forests in the high-water season and often search for prey among the roots and trunks of partially submerged trees. Mark/recapture studies have shown that some individuals are resident to specific areas year-round, whereas others move several tens to hundreds of kilometers within the rivers, but there does not appear to be any actual seasonal migration.

They occur most often within 150 m of the edges of rivers, with lower densities in the centers of large rivers.
Unknown; in the Amazon basin, abundance and encounter rates are only available for a few river segments. Their population does not appear to be severely fragmented but they are especially vulnerable to habitat degradation
IUCN: Data Deficient; the species was previously listed as Vulnerable but is now considered Data Deficient due to the limited amount of current information available on threats, ecology, and population numbers and trends
CITES: Appendix II
USFWS: No data

Fun Facts

  1. The Boto is the largest member of the river dolphin family (Platanistidae).
  2. The Guarayo Indians of Bolivia refer to the Boto as the Inia. The species name, geoffrensis comes from Geoffrey St. Hilaire (1772-1850). He was a prominent French professor of natural history and was instrumental in procuring the first Boto specimens.
  3. Historically, the Boto was spared from human persecution because of the belief that it had special powers.
  4. Botos have poor vision so they rely on their echolocation to navigate through the muddy waters and find food.
  5. Botos have bristle-like hairs at the ends of their snouts that help them search for food on the muddy river bottoms.

Ecology and Conservation

Hydroelectric development currently poses the biggest threat to the boto. To meet Brazil's increasing need for electric power, dam construction in the Amazon River basin is expected to increase significantly in the future. Damming activities separate dolphin populations from many fish species that they prey upon.

Agriculture poses another major threat. Clearing flood-plain forests to make way for crops and pastures affects these dolphins by eliminating part of their food chain. Some fish species rely heavily on fruits and seeds that fall from native forest trees into the water. In turn, botos rely on those fish for survival.

Toxic chemical pollutants from agricultural pesticides, mining, and paper milling are potentially harmful to the dolphins and the entire river ecosystem. Very little research has been conducted to determine concentration levels of these chemicals or their impact on the environment.

Mercury is often used to separate gold from soil and rock in mining operations along the Amazon The effects of the bioaccumulation of mercury in Botos are unknown but the high levels recorded in the Amazon ecosystem give reason for concern..

Commercial fishing in the Amazon basin is on the rise, and with it, a probable increase in dolphin mortality due to incidental entanglement in fishing nets.
The Boto is hunted for fish bait, and as human food. Botos are also killed deliberately in some areas because fishermen regard them as competitors and because they damage fishing nets (F. Trujillo pers. comm. to B.D. Smith).

In 1986, the Cetacean Specialist Group of the International Union for the Conservation of Nature and Natural Resources (IUCN) Species Survival Commission decided to concentrate its efforts on all river dolphins, which are disappearing around the world.


WWF Global – Boto – Amazon River Dolphin - Species Profile. Downloaded on 03 October 2018.

Rainforest Alliance – Amazon River Dolphin – Species Profile. Downloaded on 03 October 2018.

Reeves, R.R., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. 2011. Inia geoffrensis. The IUCN Red List of Threatened Species 2011: e.T10831A3220342. Downloaded on 03 October 2018.