View source for Giant otter

{{Short description|Species of mammal}}
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{{Speciesbox
| name = Giant otter<ref name=msw3/>
| fossil_range = {{fossilrange|0.13|0}}<small>[[Late Pleistocene]] – [[Holocene]]</small>
| image = Giant otters (Pteronura brasiliensis).jpg
| image_caption = [[Cuiabá River]], [[Mato Grosso do Sul]], [[Brazil]]
| status = EN
| status_system = IUCN3.1
| status_ref =<ref name=iucn>{{cite iucn |author1=Groenendijk, J.|author2=Leuchtenberger, C.|author3=Marmontel, M.|author4=Van Damme, P.|author5=Wallace, R.|author6=Schenck, C.|year=2022 |title=''Pteronura brasiliensis''|amends=2021|page=e.T18711A222719180|doi=10.2305/IUCN.UK.2022-2.RLTS.T18711A222719180.en|access-date=10 September 2023}}</ref>
 | status2 = CITES_A1 
 | status2_system = CITES 
 | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus = Pteronura
| parent_authority = [[John Edward Gray|Gray]], 1837
| species = brasiliensis
| authority = ([[Johann Friedrich Gmelin|Gmelin]], 1788)
| range_map = Giant Otter area.png
| range_map_caption = Giant otter range
}}

The '''giant otter''' or '''giant river otter'''<ref name="NGGRO">{{cite web|url=http://animals.nationalgeographic.com/animals/mammals/giant-river-otter/
|archive-url=https://web.archive.org/web/20100112221903/http://animals.nationalgeographic.com/animals/mammals/giant-river-otter/
|url-status=dead
|archive-date=12 January 2010
|title=Giant river otter
|publisher=National Geographic Society
|access-date=6 August 2016|date=2011-03-10
}}</ref> ('''''Pteronura brasiliensis''''') is a [[South America]]n [[carnivorous]] mammal. It is the longest member of the [[weasel]] family, [[Mustelidae]], a globally successful group of predators, reaching up to {{Height|m=1.8}}. Atypical of mustelids, the giant otter is a social species, with family groups typically supporting three to eight members. The groups are centered on a dominant [[breeding pair]] and are extremely cohesive and cooperative. Although generally peaceful, the species is territorial, and aggression has been observed between groups. The giant otter is [[Diurnality|diurnal]], being active exclusively during daylight hours. It is the noisiest [[otter]] species, and distinct vocalizations have been documented that indicate alarm, aggression, and reassurance.

The giant otter ranges across north-central South America; it lives mostly in and along the [[Amazon River]] and in the [[Pantanal]]. Its distribution has been greatly reduced and is now discontinuous. Decades of [[poaching]] for its velvety pelt, peaking in the 1950s and 1960s, considerably diminished population numbers. The species was listed as [[endangered]] in 1999 and wild population estimates are typically below 5,000. [[The Guianas]] are one of the last real strongholds for the species, which also enjoys modest numbers – and significant protection – in the Peruvian Amazonian basin. It is one of the most endangered mammal species in the [[Neotropics]]. Habitat degradation and loss is the greatest current threat. They are also rare in captivity; in 2003, only 60 giant otters were being held.<ref name=Cali>{{cite journal |last1=Londoño |first1=G. Corredor |last2=Muñoz|first2=N. Tigreros|year=2006 |title=Reproduction, behaviour and biology of the Giant river otter (''Pteronura brasiliensis'') at Cali Zoo |journal=International Zoo Yearbook |volume=40 |pages=360–371 |doi=10.1111/j.1748-1090.2006.00360.x }}</ref>

The giant otter shows a variety of adaptations suitable to an amphibious lifestyle, including exceptionally dense fur, a wing-like tail, and webbed feet. The species prefers freshwater rivers and streams, which are usually seasonally flooded, and may also take to freshwater lakes and springs. It constructs extensive campsites close to feeding areas, clearing large amounts of vegetation. The giant otter subsists almost exclusively on a [[piscivore|diet of fish]], particularly [[characin]]s and [[catfish]], but may also eat [[crab]]s, [[turtle]]s, [[snake]]s and small [[caiman]]s.<ref name=iucn/> It has no serious natural predators other than [[humans]], although it must compete with other predators, such as the [[Neotropical otter]]s and various [[crocodilia]]n species, for food resources.

== Name ==
The giant otter has a handful of other names. In Brazil it is known as ''ariranha'', from the [[Tupi language|Tupi]] word {{Lang|tup|arerãîa}}, or onça-d'água, meaning water jaguar.<ref>{{cite book |last=Ferreira |first=A. B. H. |author-link=Aurélio Buarque de Holanda Ferreira |title=Novo Dicionário da Língua Portuguesa |publisher=Nova Fronteira |year=1986 |edition=2nd |page=163 |title-link=Novo Dicionário da Língua Portuguesa }}</ref> In Spanish, river wolf ({{langx|es|lobo de río}}) and water dog ({{langx|es|perro de agua}}) are used occasionally (though the latter [[Water dog (disambiguation)|also refers to several different animals]]<!--YES, this is intentional link to a DAB page.-->) and may have been more common in the reports of explorers in the 19th and early 20th centuries.<ref>See e.g., {{harvnb|Duplaix|1980|p=547}}</ref> All four names are in use in South America, with a number of regional variations. "Giant otter" translates literally as {{Lang|es|nutria gigante}} and {{Lang|es|lontra-gigante}} in Spanish and Portuguese, respectively. Among the [[Achuar people]], they are known as ''wankanim'',<ref name=Descola/> among the [[Sanumá]] as ''hadami'',<ref>{{cite book |title=Sanuma Memories: Yanomami Ethnography in Times of Crisis |last=Ramos |first=Alcida Rita |year=1995 |publisher=University of Wisconsin Press|isbn=978-0-299-14654-2 |page=219 }}</ref><ref>"none", ''Antropológica''. 1981–1982, volume 55–58, page 107</ref>{{verify source|date=September 2023}} and among the [[Makushi]] as ''turara''.<ref>{{Cite web|title=Mammals of Iwokrama|url=https://iwokrama.org/mammals/guides/carn4.html|access-date=2023-02-06|website=iwokrama.org|archive-date=6 April 2023|archive-url=https://web.archive.org/web/20230406223318/https://iwokrama.org/mammals/guides/carn4.html|url-status=dead}}</ref> The genus name, ''Pteronura'', is derived from the [[Ancient Greek]] words {{Lang|grc|πτερόν}} ({{Transliteration|grc|pteron}}, feather or wing) and {{Lang|grc|οὐρά}} ({{Transliteration|grc|oura}}, tail),<ref name="Liddell 1980">{{cite book | author = Liddell, Henry George | author-link = Henry George Liddell | author2 = Robert Scott | author2-link = Robert Scott (philologist) | name-list-style = amp | year = 1980 | title = A Greek-English Lexicon | publisher = [[Oxford University Press]] | location = United Kingdom | isbn = 978-0-19-910207-5| title-link = A Greek-English Lexicon | edition = Abridged }}</ref> a reference to its distinctive, wing-like tail.<ref name=Koepfli/>

== Taxonomy and evolution ==
[[File:Pteronura brasiliensis MG 9021.jpg|thumb|Giant otter head from the [[Museu Paraense Emílio Goeldi]] research institute]]
The otters form the subfamily [[Lutrinae]] within the mustelids and the giant otter is the [[monotypic|only member]] of the genus ''Pteronura''. Two subspecies are currently recognized by the canonical ''[[Mammal Species of the World]]'', ''P. b. brasiliensis'' and ''P. b. paraguensis''. Incorrect [[Species description|descriptions]] of the species have led to multiple [[Synonym (taxonomy)|synonyms]] (the latter subspecies is often ''P. b. paranensis'' in the literature).<ref name=msw3>{{MSW3 Wozencraft | pages = 605}}</ref> ''P. b. brasiliensis'' is distributed across the north of the giant otter range, including the [[Orinoco]], [[Amazon River|Amazon]], and Guianas river systems; to the south, ''P. b. paraguensis'' has been suggested in [[Paraguay]], [[Uruguay]], southern [[Brazil]], and northern [[Argentina]],<ref name=FAO/> although it may be extinct in the last three of these four. The [[International Union for Conservation of Nature]] (IUCN) considers the species' presence in Argentina and Uruguay uncertain.<ref name=iucn/> In the former, investigation has shown thinly distributed population remnants.<ref>{{cite journal |last=Chehebar |first=C.|title=Searching for the Giant Otter in Northeastern Argentina |journal=IUCN Otter Specialist Group Bulletin |volume=6 |issue=1 |pages=17–18 |date=February 1991 | url=http://www.otterspecialistgroup.org/Bulletin/Volume6/Chehebar_1991.html |access-date= 2007-11-06}}</ref> ''P. b. paraguensis'' is supposedly smaller and more gregarious, with different [[dentition]] and skull [[morphology (biology)|morphology]]. Carter and Rosas, however, rejected the subspecific division in 1997, noting the classification had only been validated once, in 1968, and the ''P. b. paraguensis'' [[Type (biology)#Type specimen|type specimen]] was very similar to ''P. b. brasiliensis''.<ref name=C4>{{harvnb|Carter|Rosas|1998|p=4}}</ref> Biologist [[Nicole Duplaix]] calls the division of "doubtful value".<ref name="D511"/>

The earliest fossil evidence of the giant river otter dates to the [[Late Pleistocene]] of Argentina, and it was slightly larger than known modern specimens.<ref name=Pleistocene>{{cite journal |last1=Prevosti |first1=Francisco J. |last2=Ferrero |first2=Brenda S. |title=A Pleistocene giant river otter from Argentina: remarks on the fossil record and phylogenetic analysis |journal=Journal of Vertebrate Paleontology |date=2008 |volume=28 |issue=4 |pages=1171–1181 |doi=10.1671/0272-4634-28.4.1171|bibcode=2008JVPal..28.1171P |hdl=11336/80190 |hdl-access=free }}</ref> An extinct genus, ''[[Satherium]]'', is believed to be ancestral to the present species, having migrated to the New World during the [[Pliocene]] or early [[Pleistocene]].<ref name=Koepfli>{{cite journal |last1= Koepfli|first1=K.-P |last2=Wayne|first2=R.K.|date=December 1998 |title=Phylogenetic relationships of otters (Carnivora: Mustelidae) based on mitochondrial cytochrome b sequences |journal=Journal of Zoology |volume= 246|issue=4 |pages=401–416 |doi=10.1111/j.1469-7998.1998.tb00172.x }}</ref> The giant otter shares the South American continent with three of the four members of the New World otter genus ''[[Lontra]]'': the Neotropical river otter, the [[southern river otter]], and the [[marine otter]].<ref name=actionplan>{{cite journal|url=http://www.iucn.org/dbtw-wpd/html/Otter/cover.html |title=Otters: An Action Plan for their Conservation |year=1990 |editor1=Foster-Turley, Pat |editor2=Macdonald, Sheila |editor3=Mason, Chris |journal=IUCN/SSC Otter Specialist Group |pages=Sections 2 and 12 |access-date=2007-11-21 |url-status=dead |archive-url=https://web.archive.org/web/20080105142525/http://www.iucn.org/dbtw-wpd/html/Otter/cover.html |archive-date=5 January 2008 }}</ref> (The [[North American river otter]] (''Lontra canadensis'') is the fourth ''Lontra'' member.) The giant otter seems to have evolved independently of ''Lontra'' in South America, despite the overlap. The [[smooth-coated otter]] (''Lutrogale perspicillata'') of Asia may be its closest extant relative; similar behaviour, vocalizations, and skull morphology have been noted.<ref name=Koepfli/> Both species also show strong [[pair bonding]] and paternal engagement in rearing cubs.<ref>{{harvnb|Duplaix|1980|p=614}}</ref> Giant otter fossil remains have been recovered from a cave in the Brazilian [[Mato Grosso]].<ref>{{cite web|url=https://www.researchgate.net/publication/237221456 |title=Primeiro Registro Pleistocênico de ''Pteronura brasiliensis'' (Gmelin, 1788) (Carnivora, Mustelidae) |last=Cartelle |first=Cástor |author2=Hirooka, Suzana |publisher=Arquivos do Museu Nacional, Rio de Janeiro Publishing |date=September 2005 |website=ResearchGate |access-date=9 October 2018}}</ref>

[[Phylogenetic]] analysis by Koepfli and Wayne in 1998 found the giant otter has the highest divergence sequences within the otter subfamily, forming a distinct [[clade]] that split away 10 to 14&nbsp;million years ago. They noted that the species may be the [[Basal (phylogenetics)|basal]] divergence among the otters or fall outside of them altogether, having split even before other mustelids, such as the [[Stoat|ermine]], [[Mustelinae|polecat]], and [[mink]].<ref name=Koepfli/> Later [[DNA sequencing|gene sequencing]] research on the mustelids, from 2004, places the divergence of the giant otter somewhat later, between five and 11&nbsp;million years ago; the corresponding [[phylogenetic tree]] locates the ''Lontra'' divergence first among otter genera, and ''Pteronura'' second, although divergence ranges overlap.<ref>{{cite journal |last1=Marmi |first1=Josep |last2=Lopez-Giraldez|first2=Juan F.|last3=Domingo-Roura|first3=Xavier |date=November 2004|title=Phylogeny, evolutionary history and taxonomy of the Mustelidae based on sequences of the cytochrome b gene and a complex repetitive flanking region |journal=Zoologica Scripta |volume= 33|issue=6 |pages= 481–499|doi=10.1111/j.0300-3256.2004.00165.x|s2cid=85818256 }}</ref>

== Physical characteristics ==
[[File:Giant Otter Anjo.JPG|thumb|A wild giant otter "periscoping" in [[Cantão State Park]] in Brazil, showing its identifying throat marks]]
[[File:Pteronura brasiliensis 02 MWNH 837.jpg|thumb|Skull seen from the side. Short-snouted as usual in mustelids, it has a pronounced [[sagittal crest]], allowing for a very powerful bite in this species.]]
The giant otter is clearly distinguished from other otters by morphological and behavioural characteristics. It has the greatest body length of any species in the mustelid family, although the [[sea otter]] may be heavier. Males are between {{Height|m=1.5 and 1.7}} in length from head to tail and females between {{Height|m=1 and 1.5}}. The animal's well-muscled tail can add a further {{convert|70|cm|in|abbr=on}} to the total body length.<ref>{{cite web |url=http://www.nature.org/animals/mammals/animals/giantotter.html |title=Giant Otter (''Pteronura brasiliensis'') |access-date=2008-01-25 |publisher=[[The Nature Conservancy]] |archive-url=https://web.archive.org/web/20090525020045/http://www.nature.org/animals/mammals/animals/giantotter.html |archive-date=25 May 2009 |url-status=dead }}</ref><ref>Boitani, Luigi, ''Simon & Schuster's Guide to Mammals''. Simon & Schuster/Touchstone Books (1984), {{ISBN|978-0-671-42805-1}}</ref> Early reports of skins and living animals suggested exceptionally large males of up to {{Height|m=2.4}}; intensive hunting likely reduced the occurrence of such massive specimens. Weights are between {{convert|26|and|32|kg|lb|abbr=on}} for males and {{convert|22|and|26|kg|lb|abbr=on}} for females.<ref>{{harvnb|Duplaix|1980}}</ref>
The giant otter has the shortest fur of all otter species; it is typically chocolate brown, but may be reddish or [[fawn (color)|fawn]], and appears nearly black when wet.<ref name=C2>{{harvnb|Carter|Rosas|1998|p=2}}</ref> The fur is extremely dense, so much so that water cannot penetrate to the skin.<ref name=Philly>{{cite web|url=http://www.philadelphiazoo.org/Animals/Mammals/Carnivora/Giant-Otter.aspx |title=Giant Otter |access-date=2007-11-06 |work=Meet Our Animals |publisher=[[Philadelphia Zoo]] |url-status=dead |archive-url=https://web.archive.org/web/20130411191811/http://www.philadelphiazoo.org/Animals/Mammals/Carnivora/Giant-Otter.aspx |archive-date=11 April 2013 }}</ref> [[Guard hair]]s trap water and keep the inner fur dry; the guard hairs are approximately 8&nbsp;millimetres (one-third of an inch) in length, about twice as long as the fur of the inner coat.<ref name=Seaworld>{{cite web |url=http://www.seaworld.org/animal-info/info-books/otters/physical-characteristics.htm |title=Otters: Physical characteristics |access-date=2007-11-06 |publisher=Anheuser-Busch Adventure Parks |archive-url=https://web.archive.org/web/20071102220803/http://www.seaworld.org/animal-info/info-books/otters/physical-characteristics.htm |archive-date=2 November 2007 |url-status=dead }}</ref> Its velvety feel makes the animal highly sought after by fur traders and has contributed to its decline.<ref name=EE>{{cite web |url=http://www.earthsendangered.com/profile.asp?ID=11&sp=311 |title=Giant Otter Facts |access-date=2007-11-07|work=Meet Our Animals |publisher=Earth's Endangered Creatures}}</ref> Individuals can be identified from birth by unique markings of white or cream fur on the throat and under the chin.<ref name=C2/>

Giant otter muzzles are short and sloping and give the head a ball-shaped appearance.<ref name=D511>{{harvnb|Duplaix|1980|p=511}}</ref> The ears are small and rounded.<ref name=Philly/> The nose (or [[rhinarium]]) is completely covered in fur, with only the two slit-like nostrils visible. The giant otter's highly sensitive whiskers ([[vibrissae]]) allow the animal to track changes in water pressure and currents, which aids in detecting prey.<ref name=WWF>{{cite web |url=http://www.panda.org/news_facts/education/best_place_species/current_top_10/giant_otter.cfm |title=Giant Otter |access-date=2008-01-19 |publisher=[[World Wildlife Fund]] |archive-url = https://web.archive.org/web/20071024031504/http://www.panda.org/news_facts/education/best_place_species/current_top_10/giant_otter.cfm |archive-date=24 October 2007 |url-status=dead}}</ref> The legs are short and stubby and end in large webbed feet tipped with sharp claws. Well suited for an aquatic life, it can close its ears and nose while underwater.<ref>{{cite web |url= http://www.iwokrama.org/forest/animals/giantotter.htm |title=Giant Otter, the "Water Dog" |access-date=2007-11-07 |publisher= Iwokrama International Centre for Rainforest Conservation and Development |archive-url=https://web.archive.org/web/20071017182623/http://www.iwokrama.org/forest/animals/giantotter.htm <!--Added by H3llBot--> |archive-date=2007-10-17 }}</ref>

At the time of Carter and Rosas's writing, vision had not been directly studied, but field observations show the animal primarily hunts by sight; above water, it is able to recognize observers at great distances. The fact that it is exclusively active during the day further suggests its eyesight should be strong, to aid in hunting and predator avoidance. In other otter species, vision is generally [[emmetropic|normal]] or slightly [[myopic]], both on land and in water. The giant otter's hearing is acute and its sense of smell is excellent.<ref name=C2/><ref name=D533>{{harvnb|Duplaix|1980|p=533}}</ref>

The species possesses 2n&nbsp;= 38 chromosomes.<ref>{{cite journal|last1=Franco-de-Sá|first1=J. F. O.|last2=Rosas|first2=F. C. W.|last3=Feldberg|first3=E.|year=2007|title=Cytogenetic study of the giant otter ''Pteronura brasiliensis'' Zimmermann 1780 (Carnivora, Mustelidae, Lutrinae)|journal=Genetics and Molecular Biology|volume=30|issue=4|pages=1093–1096|doi=10.1590/S1415-47572007000600011|doi-access=free}}</ref>

== Biology and behaviour ==
The giant otter is large, gregarious, and [[diurnality|diurnal]]. Early travelers' reports describe noisy groups surrounding explorers' boats, but little scientific information was available on the species until Duplaix's groundbreaking work in the late 1970s.<ref>{{harvnb|Duplaix|1980|p=497}}</ref> Concern over this endangered species has since generated a body of research.

=== Vocalizations ===
The giant otter is an especially noisy animal, with a complex repertoire of [[Animal communication|vocalization]]s. All otters produce vocalizations, but by frequency and volume, the giant otter may be the most vocal.<ref>{{cite web| publisher=[[SeaWorld]] |url=http://www.seaworld.org/Animal-info/info-books/otters/pdf/ib-otters.pdf |title=Otters: A SeaWorld Education Department Publication |year=2005 |access-date=2008-01-23 |url-status=dead |archive-url=https://web.archive.org/web/20080715045541/http://www.seaworld.org/animal-info/info-books/otters/pdf/ib-otters.pdf |archive-date=15 July 2008 }}</ref> Duplaix identified nine distinct sounds, with further subdivisions possible, depending on context. Quick ''hah'' barks or explosive snorts suggest immediate interest and possible danger. A wavering scream may be used in bluff charges against intruders, while a low growl is used for aggressive warning. Hums and coos are more reassuring within the group. Whistles may be used as advance warning of nonhostile intent between groups, although evidence is limited. Newborn pups squeak to elicit attention, while older young whine and wail when they begin to participate in group activities.<ref>{{harvnb|Duplaix|1980|pp=552–561}}</ref> An analysis published in 2014 cataloged 22 distinct types of vocalization in adults and 11 in neonates.<ref name = "Mumm2014">{{Cite journal | doi = 10.1371/journal.pone.0112562| title = The Vocal Repertoire of Adult and Neonate Giant Otters (''Pteronura brasiliensis'')| journal = PLOS ONE| volume = 9| issue = 11| pages = e112562| date = 2014-11-12| last1 = Mumm | first1 = C. A. S. | last2 = Knörnschild | first2 = M. | pmid=25391142 | pmc=4229255| bibcode = 2014PLoSO...9k2562M| doi-access = free}}</ref> Each family of otters was shown to have its own unique audio signature.<ref>{{cite journal|last1=Mumm|first1=C. A.|last2=Knörnschild|first2=M.|year=2017|title=Territorial choruses of giant otter groups (''Pteronura brasiliensis'') encode information on group identity|journal=PLOS ONE|volume=12|issue=10|pages=e0185733|doi=10.1371/journal.pone.0185733|pmid=29023545|pmc=5638252|bibcode=2017PLoSO..1285733M|doi-access=free}}</ref>

=== Social structure ===
The giant otter is a highly social animal and lives in extended family groups. Group sizes are anywhere from two to 20 members, but likely average between three and eight.<ref name=FAO>{{cite web |url=http://www.fao.org/docrep/t0750e/t0750e0i.htm |title=Pteronura brasiliensis (giant otter) |access-date=2007-11-07 |publisher=Food and agricultural organization of the United Nations |work=Carnivores |archive-url = https://web.archive.org/web/20071127101743/http://www.fao.org/docrep/t0750e/t0750e0i.htm |archive-date=27 November 2007 |url-status=dead}}</ref> (Larger figures may reflect two or three family groups temporarily feeding together.)<ref name=vandamme2002/>

[[File:Giant otter 3.jpg|thumb|Giant otters leave a pool together at the [[Philadelphia Zoo]]. The species is extremely social, a rarity among mustelids, and family groups are cohesive.]]
Group members share roles, structured around the dominant breeding pair. The species is territorial, with groups marking their ranges with [[latrine (animal)|latrine]]s, gland secretions, and vocalizations.<ref name=Ribas05>{{cite journal |last1=Ribas |first1=Carolina |last2=Mourão|first2=Guilherme |date=January 2005 |title=Intraspecific Agonism between Giant Otter Groups |journal=IUCN Otter Specialist Group Bulletin|volume=21 |issue=2 |pages=89–93 |url=http://iucnosg.org/Bulletin/Volume21/Ribas_Mourao_2004.html |access-date= 2007-11-07 }}</ref> At least one case of a change in alpha relationship has been reported, with a new male taking over the role; the mechanics of the transition were not determined.<ref name=Evan07/> Duplaix suggests a division between "residents", who are established within groups and territories, and nomadic and solitary "transients"; the categories do not seem rigid, and both may be a normal part of the giant otter life cycle.<ref>{{harvnb|Duplaix|1980|pp=571–2}}</ref> One tentative theory for the development of sociality in mustelids is that locally abundant but unpredictably dispersed prey causes groups to form.<ref name=Johnson00/>

Aggression within the species ("intraspecific" conflict) has been documented. Defence against intruding animals appears to be cooperative: while adult males typically lead in aggressive encounters, cases of alpha females guarding groups have been reported.<ref name=Evan07>{{cite journal |last= Evangelista |first=Emanuela |date=July 2004 |title=Change of Partners in a Giant Otter Alpha Couple |journal=IUCN Otter Specialist Group Bulletin|volume=21 |issue=1 |pages=47–51 |url=http://www.otterspecialistgroup.org/Bulletin/Volume21/Evangelista_2004.html |access-date= 2007-11-07 }}</ref> One fight was directly observed in the Brazilian [[Pantanal]] in which three animals violently engaged a single individual near a range boundary.<ref name=Ribas05/> In another instance in Brazil, a carcass was found with clear indications of violent assault by other otters, including bites to the snout and genitals, an attack pattern similar to that exhibited by captive animals.<ref>{{cite journal |last1=Rosas |first1=F.C.W. |last2=De Mattos|first2=G.E.|date=October 2003|title=Natural Deaths of Giant Otters (''Pteronura brasiliensis'') In Balbina Hydroelectric Lake, Amazonas, Brazil |journal=IUCN Otter Specialist Group Bulletin |volume=20 |issue=2 |pages=62–64 |url=http://www.otterspecialistgroup.org/Bulletin/Volume20/Weber_Rosas_de_Mattos_2003.html |access-date= 2007-11-07}}</ref> While not rare among large predators in general, intraspecific aggression is uncommon among otter species; Ribas and Mourão suggest a correlation to the animal's sociability, which is also rare among other otters.<ref name=Ribas05/>
<!--http://iucnosg.org/Bulletin/Volume18/Groenendijk_et_al_2001.html-->A capacity for aggressive behavior should not be overstated with the giant otter. Researchers emphasize that even between groups, conflict avoidance is generally adopted.<ref>{{harvnb|Duplaix|1980|p=563}}</ref><ref name = C15/> Within groups, the animals are extremely peaceful and cooperative. Group hierarchies are not rigid and the animals easily share roles.<ref>{{cite journal |last1=Schenck |first1=C. |last2=Staib|first2=E. |date=April 1992 |title=Giant Otters in Peru |journal=IUCN Otter Specialist Group Bulletin |volume=7 |pages= 24–26|url=http://www.otterspecialistgroup.org/Bulletin/Volume7/Schenk_Staib_1992.html |access-date= 2008-01-22}}</ref>

=== Reproduction and life cycle ===
[[File:Giant Otter Den.JPG|thumb|A giant otter den dug on a lakeshore at [[Cantão State Park]] – the newly dug white sand is a sign of recent activity at this den.]]
Giant otters build dens, which are holes dug into riverbanks, usually with multiple entrances and multiple chambers inside. They give birth within these dens during the dry season.  In [[Cantão State Park]], otters dig their reproductive dens on the shores of [[oxbow lake]]s starting around July, when waters are already quite low. They give birth between August and September, and the young pups emerge for the first time in October and November, which are the months of lowest water when fish concentrations in the dwindling lakes and channels are at their peak. This makes it easier for the adults to catch enough fish for the growing young, and for the pups to learn how to catch fish. The entire group, including nonreproductive adults, which are usually older siblings to that year's pups, collaborates to catch enough fish for the young.<ref name="Araguaia-Giant-Otter">
{{cite web
 | title = Giant Otters in Cantão
 | url = http://www.araguaia.org/cantao/Giant_Otter_Project_2_2.html
 | publisher = Instituto Araguaia
 | access-date = 10 March 2011
 | archive-url = https://web.archive.org/web/20170626193418/http://www.araguaia.org/cantao/Giant_Otter_Project_2_2.html
 | archive-date = 26 June 2017
 | url-status = dead
 }}
</ref>

Details of giant otter reproduction and life cycle are scarce, and captive animals have provided much of the information. Females appear to give birth year round, although in the wild, births may peak during the dry season. The [[estrous]] cycle is 21 days, with females receptive to sexual advances between three and 10 days.<ref name=C18>{{harvnb|Carter|Rosas|1998|p=18}}</ref> Study of captive specimens has found only males initiate [[copulation (zoology)|copulation]].<ref name=Cali/> At [[Tierpark Hagenbeck]] in Germany, long-term [[pair bond]]ing and individualized mate selection were seen, with copulation most frequently taking place in water.<ref name=Germany/> Females have a [[gestation]] period of 65 to 70 days, giving birth to one to five pups, with an average of two.<ref name=C18/><ref name=Germany>{{cite journal |last1=Hagenbeck |first1=Carl |last2=Wunnemann|first2=Claus |year=1992 |title=Breeding the giant otter (''Pteronura brasiliensis'') at Carl Hagenbecks Tierpark |journal=International Zoo Yearbook |volume=32 |pages=240–245 |doi=10.1111/j.1748-1090.1991.tb02392.x}}</ref> Research over five years on a breeding pair at the [[Cali Zoo]] in Colombia found the average interval between litters was six to seven months, but as short as 77 days when the previous litter did not survive.<ref name=Cali/> Other sources have found greater intervals, with as long as 21 to 33 months suggested for otters in the wild.<ref name=C18/>
[[File:Pteronura brasiliensis (Alua and Yumbo) Parken Zoo.jpg|thumb|upright|left|Captive giant otters have contributed greatly to scientific knowledge of the species by providing readily available subjects for research on the species' reproduction and life cycle.]]
Mothers give birth to furred and blind cubs in an underground den near the river shore and fishing sites.<ref>{{harvnb|Duplaix|1980|p=567}}</ref> Males actively participate in rearing cubs and family cohesion is strong;<ref>{{harvnb|Duplaix|1980|p=576}}</ref> older, juvenile siblings also participate in rearing, although in the weeks immediately after birth, they may temporarily leave the group.<ref name=C18/> Pups open their eyes in their fourth week, begin walking in their fifth, and are able to swim confidently between 12 and 14 weeks old.<ref name=Cali/> They are weaned by nine months and begin hunting successfully soon after.<ref name=C18/> The animal reaches [[sexual maturity]] at about two years of age and both male and female pups leave the group permanently after two to three years.<ref name=C18/><ref name=Germany/> They then search for new territory to begin a family of their own.<ref name=Dortmund/>

Studies of giant otters in captivity have given indications about the environment necessary to both maintain a physically and behaviorally healthy population and allow successful cub-rearing. These include providing at least the minimum recommended land-to-water area ratio, and that all enclosure land surfaces (both artificial and natural) are nearly entirely covered with the recommended substrate conditions (e.g. tree-bark mulch and soft pebble-free sand/soil). Ensuring that the animals have sufficient privacy from human disturbances (visual and acoustic, from zoo staff or visitors) at parturition and during cub-rearing is also essential, but not sufficient. Insufficient land area proportions and unsuitable substrate conditions in zoos have historically been the primary cause of high cub mortality and physical and behavioral health problems among giant otters. For example, stress to the parents during cub-rearing due to inappropriate enclosure conditions has been the primary reason for cub neglect, abuse and infanticide.<ref name="Dortmund" /><ref name=stud>{{cite book|last1=Sykes-Gatz|first1=S.|last2=Gatz|first2=V.|year=2011|title=International Studbook for the Giant Otter (Pteronura brasiliensis) (Gray 1867)|edition=2nd|publisher=Zoologischer Garten Dortmund|location=Germany}}</ref><ref name=EEP>{{cite report|last1=Gatz|first1=V.|last2=Sykes-Gatz|first2=S.|title=Giant Otter EEP Annual Report 2003, 2007, 2010|series=EAZA Yearbook 2003, 2007, 2010|publisher=EAZA Executive Office (European Association of Zoos and Aquariums)|location=Amsterdam}}</ref>

In the wild, it has been suggested, although not systematically confirmed, that tourists cause similar stresses: disrupted lactation and denning, reduced hunting, and habitat abandonment are all risks.<ref name=Dortmund/> This sensitivity is matched by a strong protectiveness towards the young. All group members may aggressively charge intruders, including boats with humans in them.<ref>{{harvnb|Duplaix|1980|pp=564–5, 570}}</ref>

The longest documented giant otter lifespan in the wild is eight years. In captivity, this may increase to 17, with an unconfirmed record of 19. The animal is susceptible to a variety of diseases, including [[canine parvovirus]]. Parasites, such as the larvae of flies and a variety of intestinal worms, also afflict the giant otter.<ref name=Dortmund>{{cite book |title= International Giant Otter Studbook Husbandry and Management Information and Guidelines |last=Sykes-Gatz |first=S. |year=2005 |publisher=Zoologischer Garten Dortmund |location=Germany |edition=Second |page=13 }}</ref> Other causes of death include accidents, [[gastroenteritis]], infanticide, and [[epileptic]] seizures.<ref name=C18/>

=== Hunting and diet ===
[[File:Riesenotter.jpg|right|thumb|A captive giant otter, when feeding, grasps prey in its forepaws and begins eating immediately, at the head.]]
The giant otter is an [[apex predator]], and its population status reflects the overall health of riverine ecosystems.<ref name=Barnett00>{{cite journal |last1=Barnett |first1=Adrian |last2=Shapley|first2=Rebecca |last3=Lehman|first3=Shawn|last4=Henry|first4=Everton|last5=Benjamin|first5=Paul|date=October 2000 |title=Records of the Giant Otter, ''Pteronura brasiliensis'', from Guyana |journal=IUCN Otter Specialist Group Bulletin |volume=17 |issue=2 |pages= 65–74|url=http://www.rebeccashapley.com/akodon/reprint_pdfs/00GuyanaGiantOtter.pdf|via=rebeccashapley.com|access-date=10 September 2023}}</ref> It feeds mainly on fish, including [[cichlids]], [[perch]], [[characin]]s (such as [[piranha]]), and [[catfish]].<ref name="Bender">{{Cite web|url=https://animaldiversity.org/accounts/Pteronura_brasiliensis/|title=Pteronura brasiliensis (giant otter)|first=Jamie|last=Bender|website=Animal Diversity Web}}</ref> One full-year study of giant otter scats in Amazonian Brazil found fish present in all fecal samples. Fish from the [[order (biology)|order]] [[Perciformes]], particularly cichlids and perch, were seen in 97% of scats, and [[Characiformes]], such as characins, in 86%. Fish remains were of medium-sized species that seem to prefer relatively shallow water, to the advantage of the visually oriented giant otter. Prey species found were also sedentary, generally swimming only short distances, which may aid the giant otter in predation.<ref name="Rosas-1999" /> Hunting in shallow water has also been found to be more rewarding, with water depth less than {{convert|0.6|m|ft|}} having the highest success rate.<ref name=C16>{{harvnb|Carter|Rosas|1998|p=16}}</ref> The giant otter seems to be [[opportunist predator|opportunistic]], taking whatever species are most locally abundant.<ref name="Rosas-1999">{{cite journal |first1=Fernando C.W.|last1=Rosas |last2=Zuanon|first2=Jansen A.S.|date=September 1999 |title=Feeding Ecology of the Giant Otter, ''Pteronura brasiliensis'' |journal=Biotropica |volume= 31|issue=3 |pages= 502–506 |doi=10.1111/j.1744-7429.1999.tb00393.x |s2cid=86658847|last3=Carter|first3=Sarah K.|bibcode=1999Biotr..31..502R }}</ref> If fish are unavailable, it will also take [[crab]]s, other [[crustacean]]s, [[snake]]s, and even small [[caiman]]s and [[anaconda]]s.<ref name="Bender">{{Cite web|url=https://animaldiversity.org/accounts/Pteronura_brasiliensis/|title=Pteronura brasiliensis (giant otter)|first=Jamie|last=Bender|website=Animal Diversity Web}}</ref><ref name=OSF>{{cite web |url=http://www.otter.org/otterframes.html |title=Giant Otter (''Pteronura brasiliensis'') |access-date=2007-11-21 |publisher=International Otter Survival Fund | archive-url = https://web.archive.org/web/20071011034243/http://www.otter.org/otterframes.html| archive-date=11 October 2007}}</ref>

The species can hunt singly, in pairs, and in groups, relying on sharp eyesight to locate prey.<ref name=D544>{{harvnb|Duplaix|1980|pp=544–6}}</ref> In some cases, supposed cooperative hunting may be incidental, a result of group members fishing individually in close proximity; truly coordinated hunting may only occur where the prey cannot be taken by a single giant otter, such as with small anacondas and juvenile [[black caiman]].<ref name=C15>{{harvnb|Carter|Rosas|1998|p=15}}</ref> The giant otter seems to prefer [[prey fish]] that are generally immobile on river bottoms in clear water. Prey chase is rapid and tumultuous, with lunges and twists through the shallows and few missed targets. The otter can attack from both above and below, swiveling at the last instant to clamp the prey in its jaws. Giant otters catch their own food and consume it immediately; they grasp the fish firmly between the forepaws and begin eating noisily at the head.<ref name=D544/> Carter and Rosas have found captive adult animals consume around 10% of their body weight daily—about {{convert|3|kg|lb|0}}, in keeping with findings in the wild.<ref name=C17>{{harvnb|Carter|Rosas|1998|p=17}}</ref>

== Ecology ==

=== Habitat ===
The species is amphibious, although primarily terrestrial.<ref name=WWF02>{{cite report|title=Guianas Rapid River Bio-assessments and Giant Otter Conservation Project |publisher=[[World Wildlife Fund]]|url=http://www.giantotterresearch.com/articles/WWF_Giant_Otter_Report_PDFMini.pdf |first=Nicole|last=Duplaix|year=2002}}</ref> It occurs in freshwater rivers and streams, which generally flood seasonally. Other water habitats include freshwater springs and permanent freshwater lakes.<ref name=iucn/> Four specific vegetation types occur on one important creek in Suriname: riverbank high forest, floodable mixed marsh and high swamp forest, floodable low marsh forest, and grass islands and floating meadows within open areas of the creek itself.<ref name=WWF02/> Duplaix identified two critical factors in habitat selection: food abundance, which appears to positively correlate to shallow water, and low sloping banks with good cover and easy access to preferred water types. The giant otter seems to choose clear, black waters with rocky or sandy bottoms over silty, saline, and white waters.<ref>{{harvnb|Duplaix|1980|pp=514–5}}</ref> [[File:Four Giant Otters.JPG|thumb|A group of four giant otters emerging from the water to patrol a campsite on the riverbank at Cantão State Park]]

Giant otters use areas beside rivers for building dens, campsites, and latrines.<ref name=Utreras05>{{cite journal |last1=Utreras B.|first1=V.|last2=Suárez R.|first2=E.|last3=Zapata-Ríos|first3=G.|last4=Lasso|first4=G.|last5=Pinos|first5=L.|date=July–December 2005 |title=Dry and Rainy Season Estimations of Giant Otter, ''Pteronura brasiliensis'', Home-Range in the Yasuní National Park, Ecuador |journal=The Latin American Journal of Aquatic Mammals |volume= 4|issue=2 |pages=191–194 |url=http://plaza.ufl.edu/galo/Nutria%20Yasuni.pdf |access-date= 2007-11-07 |doi=10.5597/lajam00085|doi-access=free }}</ref> They clear significant amounts of vegetation while building their campsites. One report suggests maximum areas {{convert|28|m|ft|0|abbr=on}} long and {{convert|15|m|ft|0|abbr=on}} wide, well-marked by [[scent gland]]s, urine, and feces to signal territory.<ref name=actionplan/> Carter and Rosas found average areas a third this size. Giant otters adopt communal latrines beside campsites, and dig dens with a handful of entrances, typically under root systems or fallen trees. One report found between three and eight campsites, clustered around feeding areas. In seasonally flooded areas, the giant otter may abandon campsites during the wet season, dispersing to flooded forests in search of prey.<ref name=C13>{{harvnb|Carter|Rosas|1998|p=13}}</ref> Giant otters may adopt preferred locations perennially, often on high ground. These can become quite extensive, including "backdoor" exits into forests and swamps, away from the water.<ref name=WWF02/> Otters do not visit or mark every site daily, but usually patrol all of them, often by a pair of otters in the morning.<ref>{{harvnb|Duplaix|1980|p=69}}</ref>

Research generally takes place in the dry season and an understanding of the species' overall habitat use remains partial. An analysis of dry season range size for three otter groups in Ecuador found areas between {{convert|0.45|and|2.79|km2|sqmi}}. Utreras<ref name=Utreras05/> presumed habitat requirements and availability would differ dramatically in the rainy season: estimating range sizes of 1.98 to as much as 19.55&nbsp;square kilometres (0.76 to 7.55&nbsp;sq&nbsp;miles) for the groups. Other researchers suggest approximately {{convert|7|km2|sqmi}} and note a strong inverse correlation between [[social behaviour|sociality]] and home range size; the highly social giant otter has smaller home range sizes than would be expected for a species of its mass.<ref name=Johnson00>{{cite journal |last1=Johnson |first1=Dominic D.P. |last2=MacDonald|first2=David W.|last3=Dickman|first3=Amy J.|year=2000 |title=An analysis and review of the sociobiology of the Mustelidae|journal=Mammal Review |volume=30 |issue=3&4 |pages=171–196 |url=http://www.princeton.edu/~dominic/2000%20-%20Johnson%20et%20al.%20-%20Mustelids%20-%20Mamm.%20Rev.pdf |access-date= 2007-11-07 |doi=10.1046/j.1365-2907.2000.00066.x |archive-url = https://web.archive.org/web/20060919100534/http://www.princeton.edu/~dominic/2000%20-%20Johnson%20et%20al.%20-%20Mustelids%20-%20Mamm.%20Rev.pdf |archive-date=19 September 2006 |url-status=dead}} See figure three for home range size estimate.</ref> Population densities varied with a high of {{convert|1.2|/km2|/sqmi|abbr=on}} reported in Suriname and with a low of {{convert|0.154|/km2|/sqmi|abbr=on}}<!-- one animal per {{convert|6.5|km2|sqmi|abbr=on}} --> found in Guyana.<ref name=FAO/>

In 2021, conservationists at Fundación Rewilding spotted a wild giant otter swimming in the [[Bermejo River]] in [[Impenetrable National Park]], located in the Chaco province of northeast Argentina.<ref>{{Cite web|url=https://earther.gizmodo.com/giant-river-otter-believed-to-be-extinct-has-been-spott-1846963673|title = Giant River Otter Believed to be Extinct Has Been Spotted in Argentina| date=25 May 2021|last=Noor|first=Dharna|access-date=10 September 2023|website=Gizmodo}}</ref>

=== Predation and competition ===
[[File:Piranha1.jpg|thumb|right|Characins such as piranha species are prey for the giant otter, but these aggressive fish may also pose a danger. Duplaix speculated that piranhas may attack giant otters.]]
Adult giant otters living in family groups have no known serious natural [[predator]]s; however, there are some accounts of [[black caiman]]s in [[Peru]] and [[yacare caiman]]s in the [[Pantanal]] preying on giant otters.<ref name="C17"/> In addition, solitary animals and young may be vulnerable to attacks by the [[jaguar]], [[cougar]], and [[anaconda]], but this is based on historical reports, not direct observation.<ref>{{harvnb|Duplaix|1980|pp=523, 529}}</ref> Pups are more vulnerable, and may be taken by caiman and other large predators,<ref name=Dortmund/> although adults are constantly mindful of stray young, and will harass and fight off possible predators. When in the water, the giant otter faces danger from animals not strictly preying upon it: the [[electric eel]] and [[stingray]] are potentially deadly if stumbled upon, and piranha may be capable of at least taking bites out of a giant otter, as evidenced by scarring on individuals.<ref name="D529"/>

Even if without direct predation, the giant otter must still compete with other predators for food resources. Duplaix documented interaction with the Neotropical otter.<ref>''Lontra longicaudis.'' In {{harvnb|Duplaix|1980}} it was listed as the Guiana Otter under the older binomial ''Lutra enudris''.</ref> While the two species are [[sympatric]] (with overlapping ranges) during certain seasons, there appeared to be no serious conflict. The smaller neotropical otter is far more shy, less noisy, and less social; at about a third the weight of the giant otter, it is more vulnerable to predation, hence, a lack of conspicuousness is to its advantage. The neotropical otter is active during twilight and darkness, reducing the likelihood of conflict with the diurnal giant otter.<ref>{{harvnb|Duplaix|1980|pp=527–9}}</ref> Its smaller prey, different denning habits, and different preferred water types also reduce interaction.<ref name=C17/>

Other species that prey upon similar food resources include the caimans and large fish that are themselves [[piscivore]]s. [[Gymnotid]]s, such as the electric eel, and the large [[silurid]] catfish are among aquatic competitors. Two river dolphins, the [[tucuxi]] and [[Amazon river dolphin]], might potentially compete with the giant otter, but different spatial use and dietary preferences suggest minimal overlap.<ref name=C17/> Furthermore, Defler observed associations between giant otters and the Amazon river dolphins, and suggested that dolphins may benefit by fish fleeing from the otters.<ref name=C17/> The [[spectacled caiman]] is another potential competitor, but Duplaix found no conflict with the species in [[Suriname]].<ref>{{harvnb|Duplaix|1980|pp=522, 529}}</ref>

== Conservation status ==
The IUCN listed the giant otter as "endangered" in 1999; it had been considered "[[Vulnerable species|vulnerable]]" under all previous listings from 1982 when sufficient data had first become available. It is regulated internationally under Appendix I of the [[Convention on International Trade in Endangered Species of Wild Fauna and Flora]] (CITES) meaning commercial trade in specimens (including parts and derivatives) is prohibited.<ref>{{cite web |url=http://www.cites.org/eng/app/appendices.shtml |title=Appendices I, II and III |access-date=2008-01-22 |publisher=[[Convention on International Trade in Endangered Species of Wild Fauna and Flora]] |archive-url=https://web.archive.org/web/20071229054904/http://www.cites.org/eng/app/appendices.shtml <!--Added by H3llBot--> |archive-date=2007-12-29}}</ref>

=== Threats ===
The animal faces a variety of critical threats. [[Poaching]] has long been a problem. Statistics show between 1959 and 1969 Amazonian Brazil alone accounted for 1,000 to 3,000 pelts annually. The species was so thoroughly decimated, the number dropped to just 12 in 1971. The implementation of CITES in 1973 finally brought about significant hunting reductions,<ref name=FAO/> although demand did not disappear entirely: in the 1980s, pelt prices were as high as US$250 on the European market. The threat has been exacerbated by the otters' relative fearlessness and tendency to approach human beings. They are extremely easy to hunt, being active through the day and highly inquisitive.<ref name=Defenders>{{cite web|last=Ridgley|first=Heidi |url=http://www.giantotterresearch.com/articles/GO_article_Defenders_of_Wildlife_Winter_2007.pdf |title=The Wolf of the River |access-date=2007-11-09 |date=Winter 2007 |publisher=Defenders of Wildlife |work=Defenders Magazine }}</ref> The animal's relatively late sexual maturity and complex social life makes hunting especially disastrous.<ref name=FAO/><ref name = "Zielinski2018">{{cite web |url = https://www.sciencenews.org/blog/wild-things/social-lifestyle-river-otter-species-near-extinction |title= How a social lifestyle helped drive a river otter species to near extinction |last= Zielinski |first= S. |date= 2018-05-01 |website= [[Science News]] |access-date= 2018-05-02}}</ref><ref name="Slotow2018">{{cite journal|last1= Slotow|first1= R.|last2= Pimenta|first2=N. C.|last3= Antunes|first3=A. P.|last4= Barnett|first4=A. A.|last5= Macedo|first5=V. W.|last6= Shepard|first6=G. H.|title= Differential resilience of Amazonian otters along the Rio Negro in the aftermath of the 20th century international fur trade|journal=PLOS ONE|volume= 13|issue= 3|date= 2018-03-30|pages= e0193984|doi= 10.1371/journal.pone.0193984|pmid= 29601590|pmc= 5877832|bibcode= 2018PLoSO..1393984P|doi-access= free}}</ref>

More recently, habitat destruction and degradation have become the principal dangers, and a further reduction of 50% is expected in giant otter numbers within the 25 years after 2020 (about the span of three generations of giant otters).<ref name=iucn/> Typically, loggers first move into rainforest, clearing the vegetation along riverbanks. Farmers follow, creating depleted soil and disrupted habitats. As human activity expands, giant otter home ranges become increasingly isolated. Subadults leaving in search of new territory find it impossible to set up family groups.<ref name=Joy>{{cite web |url=http://www.otterjoy.com/otterinfo/pteronura/brasiliensis/brasiliensis_threats.html |title=Threats to the Giant Otter |access-date=2008-01-25 |publisher=Otterjoy.com |first=Lesley|last=Wright }}</ref> Specific threats from human industry include unsustainable [[mahogany]] logging in parts of the giant otter range,<ref name=Defenders/> and concentrations of [[mercury (element)|mercury]] in its diet of fish, a byproduct of gold mining.<ref>{{cite journal |last1=Fonseca |first1=Fabrizio R.D. |last2=Malm|first2=Olaf|last3=Waldemarin|first3=Helen F.|title=Mercury levels in tissues of Giant otters (''Pteronura brasiliensis'') from the Rio Negro, Pantanal, Brazil |journal=Environmental Research|volume=98 |pages=368–371 | year=2005 |url=http://www.giantotterresearch.com/articles/Articleariranhas.pdf |access-date= 2007-11-09 |doi=10.1016/j.envres.2004.11.008 |pmid=15910792 |issue=3|bibcode=2005ER.....98..368D }}</ref><ref>{{cite journal|last1=Gutleb |first1=A.C.|last2=Schenck|first2=C.|last3=Staib|first3=E.|title=Giant otter (''Pteronura brasiliensis'') at risk? Total mercury and methylmercury levels in fish and otter scats, Peru |journal=Ambio |volume=26 |issue=8 |pages=511–514 |date=December 1997 |url=http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=4314870&q=Pteronura+brasiliensis&uid=1023712&setcookie=yes |access-date=2007-11-09 |archive-url=https://web.archive.org/web/20071127121921/http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=4314870&q=Pteronura%2Bbrasiliensis&uid=1023712&setcookie=yes |archive-date=27 November 2007 |url-status=dead }}</ref>

Other threats to the giant otter include conflict with fishermen, who often view the species as a nuisance ([[#Interactions with indigenous peoples|see below]]). [[Ecotourism]] also presents challenges: while it raises money and awareness for the animals, by its nature it also increases human effect on the species, both through associated development and direct disturbances in the field.<ref name=Joy/> A number of restrictions on land use and human intrusion are required to properly maintain wild populations. Schenck ''et al.'', who undertook extensive fieldwork in Peru in the 1990s, suggest specific "no-go" zones where the species is most frequently observed, offset by observation towers and platforms to allow viewing. Limits on the number of tourists at any one time, fishing prohibitions, and a minimum safe distance of {{convert|50|m|ft|0}} are proposed to offer further protection.<ref>{{cite journal |last1=Schenck |first1=Christof |last2=Groenendijk|first2=Jessica|last3=Hajek|first3=Frank|date=April 1999 |title=Giant Otter Project In Peru: Field Trip And Activity Report, 1998 |journal=IUCN Otter Specialist Group Bulletin |volume=16 |issue=1 |pages= 33–43|url=http://www.otterspecialistgroup.org/Bulletin/Volume16/Schenck_et_al_1999.html |access-date= 2008-01-22}}</ref>

=== Distribution and population ===
[[File:Nutria_from_Venezuela.jpg|thumb|right|Giant otter from [[Venezuela]]]]
The giant otter has lost as much as 80% of its South American range.<ref name=Defenders/> While still present in a number of north-central countries, giant otter populations are under considerable stress. The IUCN lists [[Bolivia]], Brazil, [[Colombia]], [[Ecuador]], [[French Guiana]], [[Guyana]], [[Paraguay]], [[Peru]], Suriname, and [[Venezuela]] as current range countries.<ref name=iucn /> Given local extinctions, the species' range has become discontinuous.<ref name=FAO/> Total population numbers are difficult to estimate.<ref name=iucn/> Populations in Bolivia were once widespread but the country became a "black spot" on distribution maps after poaching between the 1940s and 1970s; a relatively healthy, but still small, population of 350 was estimated in the country in 2002.<ref name=vandamme2002>{{cite journal |last1=van Damme |first1=Paul |last2=Wallace|first2=Rob|last3=Swaenepoel|first3=Karen|last4=Painter|first4=Lillian|last5=Ten|first5=Silvia|last6=Taber|first6=Andrew|last7=Jimenes|first7=Rocio Gonzalez|last8=Saravia|first8=Isabel|last9=Fraser|first9=Anna|last10=Vargas|first10=Julieta|title=Distribution and Population Status of the Giant Otter ''Pteronura brasiliensis'' in Bolivia |journal=IUCN Otter Specialist Group Bulletin |volume=19 |issue=2 |pages=87–96 |date=October 2002 |url=http://www.otterspecialistgroup.org/Bulletin/Volume19/Van_Damme_et_al_2002.html |access-date= 2007-11-05|display-authors=6}}</ref> The species has likely been extirpated from southern Brazil, but in the west of the country, decreased hunting pressure in the critical [[Pantanal]] has led to very successful recolonization; an estimate suggests 1,000 or more animals in the region.<ref name=Defenders/><ref name=C8>{{harvnb|Carter|Rosas|1998|p=8}}</ref> [[File:Suriname in its region.svg|left|thumb|200px|The Guianas are the last real stronghold of the giant otter. Suriname retains extensive forest cover and many protected areas; it is pictured above. Guyana is immediately to the west and French Guiana is immediately to the east.]]

As of 2020, the IUCN estimates that there may be 4,569 otters living in Brazil.<ref name=iucn/> A significant population lives in the wetlands of the central [[Araguaia River]], and in particular within Cantão State Park, which, with its 843 [[oxbow lake]]s and extensive flooded forests and marshlands, is one of the best habitat patches for this species in Brazil.<ref name="Araguaia-Giant-Otter" />

Suriname still has significant forest cover and an extensive system of protected areas, much of which protects the giant otter.<ref>{{cite web|url=http://www.unesco-suriname.org/natural%20heritage%20in%20suriname.htm |title=Natural Heritage in Suriname |access-date=2007-01-21 |publisher=[[UNESCO]] |work=Suriname Natcom |url-status=usurped |archive-url=https://web.archive.org/web/20070307120506/http://www.unesco-suriname.org/natural%20heritage%20in%20suriname.htm |archive-date=7 March 2007 }}</ref> Duplaix returned to the country in 2000 and found the giant otter still present on the [[Kaburi Creek]], a "jewel" of [[biodiversity]], although increased human presence and land use suggests, sooner or later, the species may not be able to find suitable habitat for campsites.<ref name=Duplaix2>{{cite web |url=http://www.giantotterresearch.com/articles/KaburiAnnualReport.pdf |title=A Survey of Kaburi Creek, West Suriname, and its Conservation Implications |first1=Nicole|last1=Duplaix|last2=Lingaard|first2=Marchal|last3=Sakimin|first3=Claudine  |access-date=2008-01-22 |year=2001 |publisher=The Oceanic Society}}</ref> In a report for [[World Wildlife Fund]] in 2002, Duplaix was emphatic about the importance of Suriname and the other Guianas:<ref name=WWF02/> {{cquote|The three Guianas remain the last stronghold of giant otters in South America, with pristine giant otter habitat on some rivers and good giant otter densities overall—still, but for how long? The survival of the giant otter populations in the Guianas is essential to the survival of this endangered species in South America.}}

Other countries have taken a lead in designating protected areas in South America. In 2004, Peru created one of the largest conservation areas in the world, [[Alto Purús National Park]], with an area similar in size to Belgium. The park harbors many endangered plants and animals, including the giant otter, and holds the world record for mammal diversity.<ref>{{cite news|url=http://news.bbc.co.uk/hi/spanish/science/newsid_4399000/4399507.stm|title=Perú creará inmensa reserva amazónica|publisher=BBC Mundo|date=2005-04-01|access-date=2008-01-07|language=es}}</ref><ref>{{cite web|url=http://www.roundriver.org/Peru.html|title=The Alto Purús Conservation Project|publisher=Round River Conservation Studies|access-date=2008-01-25|archive-url = https://web.archive.org/web/20080110130750/http://www.roundriver.org/Peru.html |archive-date=10 January 2008 |url-status=dead}}</ref> Bolivia designated wetlands larger than the size of Switzerland as a freshwater protected area in 2001; these are also home to the giant otter.<ref>{{cite press release|url=http://www.ramsar.org/wn/w.n.bolivia_wwf3.htm|title=WWF welcomes Latin America's largest freshwater protected area|date=2001-09-18|publisher=The Ramsar Convention on Wetlands|access-date=2008-01-27|archive-url = https://web.archive.org/web/20080222014113/http://www.ramsar.org/wn/w.n.bolivia_wwf3.htm |archive-date=22 February 2008 |url-status=dead}}</ref>

== Interactions with indigenous peoples ==
Throughout its range, the giant otter interacts with [[indigenous peoples of the Americas|indigenous groups]], who often practice traditional hunting and fishing. A study of five indigenous communities in Colombia suggests native attitudes toward the animal are a threat: the otters are often viewed as a nuisance that interferes with fishing, and are sometimes killed. Even when told of the importance of the species to ecosystems and the danger of extinction, interviewees showed little interest in continuing to coexist with the species. Schoolchildren, however, had a more positive impression of the animal.<ref name="Velasco">{{in lang|es}} Velasco, Diana Marcela (2005). [http://www.giantotterresearch.com/articles/Velasco_Inirida_Colombia.pdf "Estudio preliminar sobre el estado de conservación de la nutria gigante (Pteronura brasiliensis) en la zona de influencia de Inírida (Bajo río Inírida) Guainía, Colombia"] (PDF). Giant Otter Research. Retrieved on 2008-01-27.</ref>

In Suriname, the giant otter is not a traditional prey species for human hunters, which affords some protection.<ref name=Duplaix2/> (One researcher has suggested the giant otter is hunted only in desperation due to its horrible taste.)<ref name=Joy/> The animal sometimes drowns in nets set across rivers and machete attacks by fishermen have been noted, according to Duplaix, but "tolerance is the rule" in Suriname.<ref name=D529>{{harvnb|Duplaix|1980|pp=529–530}}</ref> One difference in behavior was seen in the country in 2002: the normally inquisitive giant otters showed "active avoidance behavior with visible panic" when boats appeared. Logging, hunting, and pup seizure may have led groups to be far more wary of human activity.<ref name=WWF02/>

Local people sometimes take pups for the [[exotic pet|exotic pet trade]] or as pets for themselves, but the animal rapidly grows to become unmanageable.<ref name=Joy/> Duplaix relates the story of an [[Arawak peoples|Arawak]] Indian who took two pups from their parents. While revealing of the affection held for the animals, the seizure was a profound blow to the breeding pair, which went on to lose their territory to competitors.<ref name=D529/>

The species has also appeared in the folklore of the region. It plays an important role in the mythology of the [[Achuar people]], where giant otters are seen as a form of the ''tsunki'', or water spirits: they are a sort of "water people" who feed on fish. They appear in a [[Fish toxins|fish poisoning]] legend where they assist a man who has wasted his sexual energy, creating the [[anaconda]]s of the world from his distressed and extended genitals.<ref name="Descola">{{cite book |title=In the Society of Nature: A Native Ecology in Amazonia |last=Descola |first=Philippe |year=1994 |publisher=Cambridge University Press|isbn=978-0-521-41103-5 |pages=280–282 }}</ref>

The [[Bororó people]] have a legend on the origin of [[tobacco smoking]]: those who used the leaf improperly by swallowing it were punished by being transformed into giant otters; the Bororo also associate the giant otter with fish and with fire.<ref>{{cite book |title=The Raw and the Cooked |last=Lévi-Strauss |first=Claude |others= trans. John Weightman and Doreen Weightman|year=1983 |publisher=University of Chicago Press|isbn=978-0-226-47487-8 |pages=104–108 }}</ref> A [[Ticuna]] legend has it that the giant otter exchanged places with the jaguar: the story says jaguar formerly lived in the water and the giant otter came to the land only to eat.<ref>{{cite book |title=El ojo que cuenta: Mitos y costumbres de la Amazonía indígena ilustrados |last=Landolt |first=Gredna |year=2005 |publisher=International Work Group for Indigenous Affairs|isbn=978-9972-2640-0-9 |page=81 }}</ref> The indigenous [[Kichwa]] peoples from Amazonian Peru believed in a world of water where [[Yacuruna|Yaku runa]] reigned as mother of the water and was charged with caring for fish and animals. Giant otters served as Yaku runa's canoes.<ref>{{cite web|last=Ching|first=César|date=October 2006|url=http://www.premioreportagem.org.br/article.sub?docId=24668&c=Peru&cRef=Peru&year=2007&date=outubro%202006 |title=PER-I38: El mundo del agua temido y poco conocido|work=BioDiversity Reporting Award. Semanario Kanatari, Iquitos, Iquitos|access-date=2008-01-27|archive-url=https://web.archive.org/web/20120210131302/http://www.premioreportagem.org.br/article.sub?docId=24668&c=Peru&cRef=Peru&year=2007&date=outubro%202006|archive-date=2012-02-10|language=es}}</ref> A [[Maxakali|Maxacali]] creation story suggests that the practice of [[otter fishing]] may have been prevalent in the past.<ref name="Warren2001">{{cite book|last=Warren|first=Jonathan W.|title=Racial Revolutions: Antiracism and Indian Resurgence in Brazil|url=https://archive.org/details/racialrevolution0000warr|url-access=registration|date=26 September 2001|publisher=Duke University Press|isbn=978-0-8223-2741-7|pages=[https://archive.org/details/racialrevolution0000warr/page/n25 1]–4}}</ref>

== Notes ==
{{Reflist}}

== References ==
{{Refbegin}}
* {{cite journal |last1=Carter |first1=S.K. |last2=Rosas |first2=F.C.W. |year=1998 |title=Biology and conservation of Giant Otter (''Pteronura brasiliensis'') |journal= Mammal Review |volume=27 |issue=1 |pages=1–26 |url=http://www.giantotterresearch.com/articles/Carter_and_Rosas_1997.pdf |access-date= 2007-11-06 |doi=10.1111/j.1365-2907.1997.tb00370.x }}
* {{cite journal |last=Duplaix |first=Nicole |year=1980 |title=Observations on the ecology and behavior of the giant river otter ''Pteronura brasiliensis'' in Suriname |journal=Revue d'Écologie (La Terre et la Vie) |volume=34 |issue=4 |pages= 495–620 |doi=10.3406/revec.1980.4073 |s2cid=140641854 |url=https://hal.archives-ouvertes.fr/hal-03529307/file/bitstream_113079.pdf }}
{{Refend}}

== External links ==
{{Wikispecies|Pteronura brasiliensis}}

* {{Commons-inline|italic=1}}
* ARKive – [https://web.archive.org/web/20060223080552/http://www.arkive.org/species/GES/mammals/Pteronura_brasiliensis/ images and movies of the giant otter ''(Pteronura brasiliensis)'']

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[[Category:Otters|giant otter]]
[[Category:Apex predators]]
[[Category:Mammals of Bolivia]]
[[Category:Carnivorans of Brazil]]
[[Category:Mammals of Colombia]]
[[Category:Mammals of Ecuador]]
[[Category:Mammals of French Guiana]]
[[Category:Mammals of Guyana]]
[[Category:Mammals of Paraguay]]
[[Category:Mammals of Peru]]
[[Category:Mammals of Suriname]]
[[Category:Mammals of Venezuela]]
[[Category:Fauna of the Amazon]]
[[Category:Fauna of the Pantanal]]
[[Category:Endangered biota of South America]]
[[Category:Mammals described in 1788|giant otter]]
[[Category:Taxa named by Johann Friedrich Gmelin|giant otter]]