Pteronura brasiliensis


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Pteronura brasiliensis
Species Authority: (Gmelin, 1788)
Common Name/s:
English Giant Otter, Giant Brazilian Otter
Spanish Lobo Del Río, Arirai, Lobito De Cola Ancha, Lobo De Rio, Lobo De Río Grande, Lobo Gargantilla, Perro De Agua
French Loutre Géante Du Brésil
Taxonomic Notes: Two subspecies of have been described (Duplaix 1980): (1) P. b. brasiliensis (Gmellin, 1788) from Suriname, the Guianas, southern Venezuela, southern Colombia, eastern Ecuador, eastern Peru, Bolivia, Paraguay, and Brazil; (2) P. b. paranensis (Rengger, 1830) from the Paraguay and Parana rivers in Brazil, northern Argentina and Uruguay.

Assessment Information [top]

Red List Category & Criteria: Endangered A3cd ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor/s: Duplaix, N., Waldemarin, H.F., Groenedijk, J., Evangelista, E., Munis, M., Valesco, M. & Botello, J.C.
Reviewer/s: Hussain, S.A. & Conroy, J. (Otter Red List Authority)
This species is considered to be Endangered due to an inferred future population decline due to habitat loss and exploitation. While in the past, hunting for pelts strongly affected giant otter populations, currently the species is threatened by multiple anthropogenic influences arising from increased colonization of tropical lowland rainforests. Illegal harvesting for pelts continues in some regions, but otters are also killed by logging and mining workers who blame otters for depleting local fish resources. Otters are also taken by indigenous groups that use the meat and pelt of P. brasiliensis for subsistence (Carter and Rosas 1997). As recently as 1991, illegal trafficking in otter pelts was confirmed in Argentina although, given low populations in the country at the time, the pelts were presumed as to be imported (Chehebar 1991). There are some conflicts with fishermen as otters are perceived to reduce available fish stock although studies have shown little overlap in otter prey species and those of commercial interest (Gomez and Jorgenson 1999). Destruction of forests, leading to soil erosion and decrease of prey abundance as well as over-fishing and illegal hunting of otters are related to human colonization along rivers. Canine diseases such as parvovirus and distemper transferred through the domestic stock are as yet, an incalculable threat. In areas of gold mining, fish are getting contaminated with mercury, which is used for gold separation. Migration of contaminated fish and long-range atmospheric transport of mercury could enlarge the area of miner’s influence. Mining for oil and minerals expanding into virgin areas threatens otter habitats. Within protected areas increased tourism could change the normal behavior resulting in abandoning of territories and decrease in cub survival. Three giant otter generation lengths approximately represent a 20 year period. Accelerating habitat destruction and degradation throughout the giant otter's range is the greatest threat to the species, and is estimated to potentially lead to a future reduction in population size of around 50% over the next 20 years.
2004 Endangered
2000 Endangered
1996 Vulnerable
1994 Vulnerable (Groombridge 1994)
1990 Vulnerable (IUCN 1990)
1988 Vulnerable (IUCN Conservation Monitoring Centre 1988)
1986 Vulnerable (IUCN Conservation Monitoring Centre 1986)
1982 Vulnerable (Thornback and Jenkins 1982)

Geographic Range [top]

Range Description: P. brasiliensis is endemic to South America. The northern extent of its range occurs near, but does not include, the Caribbean Sea, and the southern extent of its range reaches Argentina, although Argentine and Uruguayan populations are thought to be extinct. The species is not found in Chile. The majority of the animals are found in the Brazilian Amazon and the regions immediately bordering this area (Kruuk 2006).
Bolivia, Plurinational States of; Brazil; Colombia; Ecuador; French Guiana; Guyana; Paraguay; Peru; Suriname; Venezuela, Bolivarian Republic of
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Distribution of the giant otter is patchy throughout its range and many remote areas have not been recently surveyed. The current total wild population is estimated at between 1,000-5,000 individuals (IUCN OSG 2006), but further surveys are required to refine this figure. Current population trends are unknown, but are thought to be declining in many areas due to habitat loss and the effects of gold mining and mercury pollution (N. Duplaix pers. comm. 2007).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: The giant otter is the largest of all the 13 otter species and is endemic to the rainforests and wetlands of South America. It is found regionally in portions of the Orinoco, Amazon, and La Plata River systems. It is known to inhabit large slow-moving rivers, streams, lakes and swamps. In a long-term study in Peru, giant otters were found in most of the river systems in the southeastern part of the country with the exception of those located close to the Andes where the flow gradient is steeper. Studies in Suriname have shown a preference for black water creeks and rivers with sandy or rocky bottoms (Duplaix 1980). The large rivers of the lowland areas with gentle flow and oxbow lakes with high fish densities represent the environment most favored by this group-living species, and areas with gently-sloped riverbanks and dense overhanging vegetation are preferred habitat features. On occasion, giant otters are seen in agricultural canals and reservoirs of small dams, although they prefer gently sloped river banks and secluded areas with overhanging vegetation. The giant otters tend to concentrate in their preferred habitats and territories can be very small (105 ha for a group of 5-8 otters).

The annual life cycle and feeding ecology of P. brasiliensis has been shown to be highly dependent upon the seasonal migrations of prey stock fish populations (Duplaix 1980). The preferred fish diet of P. brasiliensis includes members of the catfish, perch and characin families. When fish abundance is low, it feeds on crustacenas, small snakes and small caiman.

Pteronura brasiliensis lives in family groups of 5-8 individuals. Families have home ranges of 12 sq. km. Members of the family, which include a monogamous pair and several generations of offspring, clear an area along a streamside for living. These areas can be up to 50 sq meters and are usually located near feeding sites. Preparation of the living area includes trampling the surface vegetation, collecting tree limbs and leaves and embedding the leaves and branches into the trampled mud patch. Large burrows are then constructed under fallen logs. In addition, one to five communal latrines are placed along the site perimeter. Finally, the territory is marked by scent from the anal glands. If intruders invade the territory, parents defend it and their offspring.

Although separate territories are maintained, P. brasiliensis is a highly social mammal. Social activities include grooming, hunting, resting and communicating. Pteronura brasiliensis have 9 different vocalizations. The purposes for each of these sounds is undocumented, but vocalizations probably serve as warning signals against predators and/or contact calls.

Gestation is estimated to have 65-70 days and litters range from 1-5 young (average number 2). A great deal of reproductive ecology is known from studies in captivity (Redford and Eisenberg 1992), as well as some long-term studies in Peru focusing on breeding ecology and behavior. P. brasiliensis is a piscivore and preferred prey fish include members of the catfish, perch and characin families. In times of reduced prey fish availability, crustaceans, small caiman, and small snakes are opportunistically consumed (Carter and Rosas 1997).
Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s): The giant otter has very few predators. Young fall prey to caimans, jaguars, pumas, and fragmentation, and water pollution from mining and agricultural runoff. Over fishing affects their prey base. They are being affected by illegal hunting for their pelt, habitat loss and evidences that they are getting affected due to contaminants like Mercury coming from gold mines in their range. Canine and feline distemper and canine parvovirus, all introduced diseases take a heavy toll as well.

Conservation Actions [top]

Conservation Actions: The giant otter is listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), as Endangered under the United States Endangered Species Act and as Endangered under the IUCN Red List.

1) to continue assessment of predator-prey relationships, including conflicts with subsistence and commercial fishermen
2) to evaluate the positive and negative impacts of tourism in different habitats and implement management guidelines in order to maximize the benefits.
3) To encourage the development of a long-term research and conservation project in the Llanos of Venezuela of Colombia
4) To undertake collaborations between field scientists, zoos and genetic laboratories to evaluate the potential use of genetic analysis tools in giant otter research

Bibliography [top]

Baillie, J. and Groombridge, B. (comps and eds). 1996. 1996 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

Carter, S. K. and Rosas, F. C. W. 1997. Biology and conservation of the giant otter Pteronura brasiliensis. Mammal Review 27: 1-26.

Chehebar, C. 1991. News from Argentina. IUCN Otter Specialist Group Bulletin 6: 17-18.

Duplaix, N. 1980. Observations of the ecology and behaviour of the giant river otter Pteronura brasiliensis in Suriname. Revue d’Ecologie (La Terre et La Vie) 34: 495-620.

Gómez, J. R. and Jorgenson, J. P. 1999. An Overview of the Giant Otter-Fisherman Problem in the Orinoco Basin of Colombia. IUCN Otter Specialist Group Bulletin 16(2): 90-96.

IUCN. 2008. 2008 IUCN Red List of Threatened Species. Available at: (Accessed: 5 October 2008).

Kruuk, H. 2006. Otters: ecology, behaviour and conservation. Oxford University Press, Oxford.

Redford, K. H. and Eisenberg, J. F. 1992. Mammals of the Neotropics, The Southern Cone: Chile, Argentina, Uruguay, Paraguay. University of Chicago Press, Chicago, USA.

Thornback, J. and Jenkins, M. 1982. The IUCN Mammal Red Data Book. Part 1: Threatened mammalian taxa of the Americas and the Australasian zoogeographic region (excluding Cetacea). IUCN, Gland, Switzerland.

Citation: Duplaix, N., Waldemarin, H.F., Groenedijk, J., Evangelista, E., Munis, M., Valesco, M. & Botello, J.C. 2008. Pteronura brasiliensis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <>. Downloaded on 17 April 2014.
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