Habitat
Freshwater only, in rivers and channels. Fossil evidence suggests that the Boto moved
into fresh water at least 4 million years ago.
Geographical spread
South America; rivers of the Amazon and Orinoco drainage's and
isolated population in the upper Madeira in Beni, Bolivia.
Current population
Status
Considered vulnerable by the IUCN.
Size
Length 208-247cm.
Weight
85-130kg.
Normal diet
Mainly fish including many bottom-dwelling species such as catfish, also shrimps,
crabs and turtles.
Normal lifestyle
Little is known of their behaviour. These primitive dolphins have very small
brains and tend to lead solitary lives, lacking the social behaviour of modern dolphins. Botos
may occur in groups of 2-4 but rarely do. They are diurnal and nocturnal. Botos tend to occupy
specific home ranges but during the high-water season tend to go back into the flooded forest.
Feeding techniques differ during the dry and wet season, in the dry Botos share their feeding
grounds with the Tucuxis and fish at the mouths of tributaries which have strong currents and
are where there are large numbers of fish. In the wet they tend to feed separately. Botos appear
to be polygamous (rather than monogamous) and mate during the low-water season when they
tend to congregate in certain places. Females are pregnant for 10-11 months and give birth in
shallow waters between July and August. The young gather together in nurseries close to
floating grasses. The single young is weaned by 8-9 months of age.
Reasons for decline
River dolphins are the object of many superstitions and myths and are
thus rarely deliberately killed by local fishermen or hunters. However, parts of river dolphins
may be used as aprodisiacs and thus when they are accidentally caught in fishermens nets, the
eyes, teeth, genitalia or oil may be sold to local markets, such as Leticia in Colombia. The Botos
are opportunistic feeders and may enter fishermens nets in order to steal the fish, thus there
may be some conflict with locals and some have taken to shooting Botos. Swimming into nets
can also lead to death. Between 1990 and 1994 30 dead dolphins washed up in the Amazon
and 95% of these died through being trapped in nets (BBC Wildlife June 1996).
Current threats
Threatened by damage to habitat through deforestation, dam-building,
hydroelectric schemes, pollution, fishing and competition with man for food and space.
Conservation projects: In 1993 the Colombian government and locals were persauded to
prohibit the use of nets in tributaries and lakes and between 1994 ad 1995 only 2 dolphins were
found dead through entanglement in nets. Like for the Tucuxi the Omacha Foundation project
is aiming to try to raise awareness and help protect the Boto. In Colombia they are trying to set
up a reserve where river dolphins will be protected.
File last modified Thursday, October 3, 1996