Inia

The Boto, or Amazon River Dolphin (Inia geoffrensis) is a freshwater or river dolphin . It is endemic to the Amazon River and Orinoco River systems. The Boto isthe largest of the river dolphins.

The IUCN lists Amazon Dolphin, Boto Vermelho,Bouto, Bufeo, Dauphin de l'Amazone, Inia, PinkDolphin, Pink Freshwater Dolphin, Pink Porpoise, and Tonina as othernames used to describe this species.

Taxonomy

The first type specimen was described by Henri Marie Ducrotay de Blainville in 1817.

Rice's 1998 classification lists a single species, I. geoffrensis, in the genus Inia, with three recognisedsubspecies:

I.g. geoffrensis - Amazon basin population (excluding Madeirariver drainage area, above the Teotonio Rapids in Bolivia )

I.g. boliviensis - Amazon basin population in the Madeira drainage area

I.g. humboldtiana - Orinoco basin population

Some older classifications listed the boliviensis population as a separate species.

Physical description

The Boto can vary in colour from a memorable bright pink colour through to a murky brown or creamy white. Adults are typically2.5m in length and weigh 150kgs. The flippers are large compared with body size and are are curved back. The Boto does not have a dorsal fin , though a bumpy raised ridge on the back shows the evolutionaryremanants of one. Like all river dolphins, it has a prominent, long, thin beak.

The Boto is a slow-swimming animal that is not prone to gregarious behaviour. Its head is very limited in its movement becauseof tightly fused vertebrae in the neck and upper back.

Botos generally feed from the bottom of the river and their preferred diet consists of crabs and small fish.

Conservation

By the precarious standards of the river dolphins, the Boto is the most secure species in the superfamily. Nevertheless the1994 and 2000 IUCN Red List of Threatened Species classified it as vulnerable. In contrast to the rapidlydwindling areas of population of the Baiji and the Ganges and Indus River Dolphin , thearea populated by the Boto seems to have remained fairly steady over time. Although complete surveys have not been taken owing tothe inaccessibility of the rainforests, it is estimated that the total population of Botos runs into tens of thousands.

Botos have never been directly hunted. However fishermen are known to have occasionally killed animals to protect their catchand fishing gear. It is not known whether this practice is widespread enough to damage local subpopulations. Since 1988 thispractice has been outlawed in Brazil and Bolivia and in protected areas of Peru , Venezuela and Colombia .

The rising human population in the Amazon and Orinoco basins gives scientists cause for concern. Several damming projects ofthe kind that have devastated populations in Asia have been proposed for the region. Environmentalists will be vigourouslyopposed to such schemes.

Some Boto deaths occur to mercury poisoning of their environment. These deaths typically occur close to gold mines - mercury is widely used to separategold from surrounding rock.

External links

• Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans. IUCN/SSC CetaceanSpecialist Group 2003, Reeves et al. Report in PDF format (2Mb)
• Convention on Migratory Species page onthe Amazon Dolphin
• Walker's Mammals of theWorld Online - Amazon Dolphins
• Animal Info page on the Boto
• Cetacea.org page on theBoto