The giant river otter is the largest otter in the world and is found only in South
America's rivers and associated wetland habitats. From its head to the tip of its tail,
an adult otter can be 47-94 inches long - or almost 8 feet for a very large individual.
The species is prized for its dense fur, which is brown and has a velvety appearance when
dry. For swimming, the otter's large feet are webbed and its tail is muscular.
The species favors slow-moving rivers and streams, oxbow lakes, swamps, and marshes.
It feeds mainly on fish and crabs, and during the rainy season otters will follow fish as
they move into the flooded forests bordering rivers. During the dry season, when cubs are
reared, otters are less mobile, staying in a single river channel. Otters live in social
groups of around 4 to 9 individuals. Each group has a home range that consists of both
land and water and usually extends over an area of about 12 by 12 km.
Distribution and Status
The giant otter's original distribution was across much of South America, including
Colombia, Venezuela, French Guiana, Guyana, Suriname, eastern Ecuador, Peru, Brazil,
Bolivia, Paraguay, Uruguay, and northeastern Argentina. Today, the species is restricted
to a fraction of its former range.
With an estimated total population of only 1,000 to 5,000 individuals, the giant river
otter is considered highly vulnerable to extinction. In a recent analysis conducted by
World Wildlife Fund, the species was assessed as the large Neotropical vertebrate species
most vulnerable to extinction. It is also classified as vulnerable by the World
Conservation Union (IUCN), as endangered by the US Fish and Wildlife Service, and is listed
in Appendix 1 of the Convention on International Trade in Endangered Species (CITES).
Threats and Conservation
Although seemingly suitable habitat may be widespread in large areas of the otter's
range, the otter is highly vulnerable to extirpation (local extinction) due to its low
population densities, slow reproduction, a curious nature, coveted fur, and documented
rapid elimination even at low levels of hunting. Heavy hunting for the otter's valuable
pelt has been the primary reason for the species' decline. Other threats include mercury
poisoning from gold mining, pollution from fossil fuel extraction and industrial development,
disturbance from tourists, overfishing, infection by canine distemper virus transmitted by
domestic dogs, and habitat loss as a result of colonization, deforestation, and agriculture.
International bans on otter pelts have helped otters rebound in some areas, but illegal
hunting still occurs, and relatively intact populations occur in only a few areas. Giant
otters appear to have a few pockets of relatively abundant populations only in the northern
and western portions of their original range, where habitats remain relatively pristine.
World Wildlife Fund is working on developing conservation strategies for key portions of
the otter's former range, particularly in the flooded forests of the Amazon River Basin.
Classification