The giant otter is a charismatic animal that lives in the clear, white and black water rivers, streams and lakes of the floodplain forests of the Amazon basin, below 500 meters. In Bolivia it is distributed in remote areas or in protected areas in the Pando, Beni, northern La Paz, Cochabamba and Santa Cruz Departments.
It is a large mammal weighing between 22 and 34 kg. The total length measures between 141 to 200 cm and only its tail can reach a length of 40 to 70 cm. The giant otter has a characteristic white patchon its throat, which is a unique shape for each individual and equivalent to a fingerprint. It is a social carnivore and forms family groups consisting of 2 to 11 individuals. The gestation time is about 72 days, generally during the dry season, and the litter size varies from 2 to 4 offspring.
It feeds almost exclusively on fish hunting them with the help of the group, but sometimes also consumes crustaceans. The most consumed species are the wolf fish (Hoplias malabaricus), the piranha (Serrasalmus rhombeus), the curimata (Curimata spp.), and various sardine species(Triporteus spp.).
Since 2002, WCS has studied the presence, distribution and abundance of the giant otter indifferent water bodies of northern La Paz Department. After 10 years of research, 418 distribution points of the species have been gathered through direct observation, confirmed signs and interviews with park rangers and local people. WCS has elaborated distribution maps for the species and identified the most important rivers to ensure the conservation of populations at a land scape level, among them the Madidi and Heath Rivers.
Furthermore,91 individuals have been identified from their throat patches using filmed footage and photographs, and relative abundance estimated in the sampled sites with values ranging from 0.02 ind./km to 0.18 ind./km of sampled river.
In total, northern La Paz Departmentis estimated to hold around 150 and 200 individuals, representing –together with giant otter populations in neighboring southwestern Pando Department and southeastern Peru- a population stronghold of regional importance for the conservation of this endangered species. The results of our studies also suggest that giant otter populations may be slowly recovering in the northern La Paz over the last decade further stressing this regions importance for giant otter conservation, especially the Madidi River.