River dolphin: Difference between revisions

'''River dolphins''' are a [[polyphyletic]] group of fully [[aquatic mammal]]s that reside exclusively in freshwater or [[brackish water]]. They are an informal grouping of [[dolphin]]s, which itself is a [[paraphyly|paraphyletic]] group within the infraorder [[Cetacea]]. Extant river dolphins are placed in two superfamilies, '''Platanistoidea''' and '''Inioidea'''. They comprise the families [[Platanistidae]] (the South Asian dolphins), the recentlypossibly extinct [[Lipotidae]] (Yangtze riverRiver dolphin), [[Iniidae]] (the Amazonian dolphins) and [[Pontoporiidae]]. There are five [[Neontology|extant]] species of river dolphins. River dolphins, alongside other cetaceans, belong to the clade [[Artiodactyla]], with [[even-toed ungulate]]s, and their closest living relatives the [[Hippopotamidae|hippopotamuses]], from which they diverged about 40 million years ago. Specific types of Dolphinsdolphins can be pink.<ref>{{Cite web|title=Amazon River Dolphin (Pink Dolphins) {{!}} Species {{!}} WWF|url=https://www.worldwildlife.org/species/amazon-river-dolphin|access-date=2021-04-21|website=World Wildlife Fund|language=en}}</ref>

River dolphins are relatively small compared to other dolphins, having evolved to survive in warm, shallow water and strong river currents. They range in size from the {{convert|5|ft|m|sp=us|adj=on}} long [[South Asian river dolphin]] to the {{convert|8|ft|m|sp=us|adj=on}} and {{convert|220|lb|kg|adj=on}} [[Amazon river dolphin]]. Several species exhibit [[sexual dimorphism]], in that the malesfemales are larger than the femalesmales. They have streamlined bodies and two limbs that are modified into flippers. River dolphins use their conical-shaped teeth and long beaks to capture fast-moving prey in murky water. They have well-developed hearing that is adapted for both air and water; they do not really rely on vision since the water they swim in is usually very muddy. Instead, they tend to rely on [[Animal echolocation|echolocation]] when hunting and navigating. These species are well-adapted to living in warm, shallow waters, and, unlike other cetaceans, have little to no [[blubber]].

River dolphins are rarely kept in captivity; breeding success has been poor and the animals often die within a few months of capture. {{asofas of|20152020}}, there werewas only fourone river dolphinsdolphin in captivity.<ref>{{citationCite web needed|date=February2020-12-22 2018|title=The last river dolphin |url=https://uk.whales.org/2020/12/22/the-last-river-dolphin/ |access-date=2023-09-15 |website=Whale & Dolphin Conservation UK |language=en-GB}}</ref>

Four [[family (biology)|families]] of river dolphins (Iniidae, Pontoporiidae, Lipotidae and Platanistidae) are currently recognized, comprising three superfamilies (Inioidea, Lipotoidea and Platanistoidea). Platanistidae, containing the two subspecies of [[South Asian river dolphin]], is the only living family in the superfamily Platanistoidea.<ref name="Rice1998">{{cite book|author=Rice, D. W.|title=Marine Mammals of the World: Systematics and Distribution|date=1 January 1998|pages=92–95|publisher=[[Society for Marine Mammalogy]]|isbn=978-1-891276-03-3|oclc= 40622084|url=http://www.marinemammalscience.org/wp-content/uploads/2014/09/MarineMammalsOfTheWorld.pdf}}</ref> Previously, many taxonomists had assigned all river dolphins to a single family, Platanistidae, and treated the Ganges and Indus river dolphins as separate species. A December 2006 survey found no members of ''[[Baiji|Lipotes vexillifer]]'' (commonly known as the baiji, or Chinese river dolphin) and declared the species [[functionally extinct]]. With their disappearance, one of the recently accepted superfamilies, Lipotoidea, has become extinct.<ref name=Turvey2007>{{cite journal|last1=Turvey|first1=S.T.|last2=Pitman|first2=R.L.|last3=Taylor|first3=B.L.|last4=Barlow|first4=J.|last5=Akamatsu|first5=T.|last6=Barrett|first6=L.A.|last7=Zhao|first7=X. |last8=Reeves |first8=R.R.|last9=Stewart|first9=B.S.|last10=Wang|first10=K.|last11=Wei|first11=Z.|last12=Zhang|first12=X.|last13=Pusser|first13=L.T.|last14=Richlen|first14=M.|last15=Brandon|first15=J.R.|last16=Wang|first16=D.|title=First human-caused extinction of a cetacean species?|journal=Biology Letters|date=2007|volume=3|issue=5|pages=537–540|doi=10.1098/rsbl.2007.0292|pmid=17686754|pmc=2391192}}</ref>

The current classification of river dolphins is as follows:<ref name="Rice1998" /><ref name=Rice2009>{{cite book |first1=Dale W. |last1=Rice |chapter=Classification (Overall) |title=Encyclopedia of Marine Mammals |edition=2nd |year=2009 |pages=234–238 |publisher=Academic Press |doi=10.1016/B978-0-12-373553-9.00058-4 |isbn=9780123735539 |chapter-url=https://books.google.com/books?id=2rkHQpToi9sC&pg=PA234 }}</ref><ref name=Lee2012>{{cite journal | author = Lee, Y.| year = 2012 | title = First record of a platanistoid cetacean from the middle Miocene of South Korea | journal = Journal of Vertebrate Paleontology | volume = 32 | issue = 1 | pages = 231–234 | doi = 10.1080/02724634.2012.626005| bibcode = 2012JVPal..32..231L | s2cid = 129560068 |display-authors=etal}}</ref>

*** Genus ''[[La Plata dolphin|Pontoporia]]''[[File:Qiqi, a Chinese River Dolphin (Baiji) 26.jpg|thumb|[[baiji|Yangtze river dolphin]] is listed as critically endangered, likely [[Extinction|extinct]]]]

* Superfamily † [[Lipotoidea]]

** Family † [[Lipotidae]]

*** Genus † ''[[Lipotes]]''

**** † ''[[Baiji]]'' (or Chinese river dolphin), ''Lipotes vexillifer''

River dolphins are members of the infraorder ''[[Cetacea]]'', which are descendants of land-dwelling mammals of the [[order (biology)|order]] [[Artiodactyla]] (even-toed [[ungulate]]s). They are related to the ''[[Indohyus]]'', an extinct [[chevrotain|chevrotain-like]] ungulate, from which they split approximately 48 million years ago.<ref name="Ancestors_Tale">{{cite book |first=Richard |last=Dawkins |author-link=Richard Dawkins |title=The Ancestor's Tale, A Pilgrimage to the Dawn of Life |title-link=The Ancestor's Tale |publisher=Houghton Mifflin |year=2004 |pages=196–203 |isbn=978-0-618-00583-3}}</ref>

The primitive cetaceans, or [[archaeocetes]], first took to the sea approximately 49 million years ago and became fully aquatic by 5–10 million years later. It is unknown when river dolphins first ventured back into fresh water.<ref>{{cite newsgroup|url=http://phenomena.nationalgeographic.com/2015/09/09/fossil-river-dolphin-lived-out-at-sea/|archive-url=https://web.archive.org/web/20150910073803/http://phenomena.nationalgeographic.com/2015/09/09/fossil-river-dolphin-lived-out-at-sea/|url-status=dead|archive-date=September 10, 2015|last=Switek|first=Brian|title=Fossil "River Dolphin" Lived Out at Sea|date=9 September 2015|access-date= 2 November 2015}}</ref>

River dolphins are thought to have relictual distributions, that is, their ancestors originally occupied marine habitats, but were then displaced from these habitats by modern dolphin lineages.<ref name=Cassens2000>{{cite journal|last1=Cassens|first1=I.|last2=Vicario|first2=S.|last3=Waddell|first3=V.G.|last4=Balchowsky|first4=H.|last5=Van Belle|first5=D.|last6=Ding|first6=W.|last7=Fan|first7=C.|last8=Mohan|first8=R.S.|last9=Simões-Lopes|first9=P.C.|last10=Bastida|first10=R.|last11=Meyer|first11=A.|last12=Stanhope|first12=M.J.|last13=Milinkovitch|first13=M.C.|title=Independent adaptation to riverine habitats allowed survival of ancient cetacean lineages|journal=Proceedings of the National Academy of Sciences of the United States of America|date=2000|volume=97|issue=21|pages=11343–11347|doi=10.1073/pnas.97.21.11343|pmid=11027333|pmc=17202|bibcode=2000PNAS...9711343C|doi-access=free}}</ref><ref name=Hamilton2001>{{cite journal|last1=Hamilton|first1=H.|last2=Caballero|first2=S.|last3=Collins|first3=A. G.|last4=Brownell|first4=R. L.|title=Evolution of river dolphins|journal=[[Proceedings of the Royal Society B: Biological Sciences]]|date=2001|volume=268|issue=1466|pages=549–556|doi=10.1098/rspb.2000.1385|pmid=11296868|pmc=1088639}}</ref> Many of the [[Morphology (biology)|morphological]] similarities and adaptations to freshwater habitats arose due to [[convergent evolution]]; thus, a grouping of all river dolphins is [[polyphyly|polyphyletic]]. Amazon river dolphins are actually more closely related to [[Delphinoidea|oceanic dolphins]] than to [[South Asian river dolphin]]s.<ref name="Hrbek2014">{{cite journal|last1=Hrbek|first1=T.|last2=da Silva|first2=V.M.F.|last3=Dutra|first3=N.|last4=Gravena|first4=W.|last5=Martin|first5=A.R.|last6=Farias|first6=I.P.|last7=Turvey|first7=S.T.|title=A New Species of River Dolphin from Brazil or: How Little Do We Know Our Biodiversity|journal=[[PLoS ONE]]|date=2014|volume=9|issue=1|pages=e83623|doi=10.1371/journal.pone.0083623|pmid=24465386|pmc=3898917|bibcode=2014PLoSO...983623H|doi-access=free}}</ref> ''[[Isthminia panamensis]]'' is an extinct genus and species of river dolphin, living 5.8 to 6.1 million years ago. Its fossils were discovered near Piña, Panama.<ref>{{Cite web|last1=Gibbons|first1=Johnny| title = Fossil Specimen Reveals a New Species of Ancient River Dolphin|url = http://smithsonianscience.si.edu/2015/09/fossil-specimen-reveals-a-new-species-of-ancient-river-dolphin-to-smithsonian-scientists/|work=Smithsonian Science News|date=September 1, 2015|access-date = September 1, 2015}}</ref><ref>{{cite journal|last1=Pyenson|first1=N.D.|last2=Vélez-Juarbe|first2=J.|last3=Gutstein|first3=C.S.|last4=Little|first4=H.|last5=Vigil|first5=D.|last6=O'Dea|first6=A.|title=''Isthminia panamensis'', a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of 'river dolphins' in the Americas|journal=PeerJ|date=2015|volume=3|pages=e1227|doi=10.7717/peerj.1227|pmid=26355720|pmc=4562255 |doi-access=free }}</ref>

The [[tucuxi]] (''Sotalia fluviatilis'') in the [[Amazon River]] is another species descended from oceanic dolphins; however, it does not perfectly fit the label of 'facultative' either, as it occurs only in fresh water. The tucuxi was until recently considered conspecific with the [[Guiana dolphin]] (''Sotalia guianensis''), which inhabits marine waters. It may also be true for the Irrawaddy dolphin and the finless porpoise that, although the species may be found in both freshwater and marine environments, individual animals found in rivers may not be able to survive in the ocean, and vice versa.<ref>{{cite journal|first1=H.A.|last1=Cunha|first2=V.M.F.|last2=da Silva|first3=J. Jr |last3=Lailson-Brito, Jr|first4=M.C.O.|last4=Santos|first5=P.A.C.|last5=Flores|first6=A.R.|last6=Martin|first7=A.F.|last7=Azevedo|first8=A.B.L.|last8=Fragoso|first9=R.C.|last9=Zanelatto|first10=A.M.|last10=Solé-Cava|title=Riverine and marine ecotypes of ''Sotalia'' dolphins are different species|journal=Marine Biology|year=2005|volume=148|issue=2|pages=449–457|doi=10.1007/s00227-005-0078-2|bibcode=2005MarBi.148..449C |s2cid=49359327}}</ref> The tucuxi is currently classified as an oceanic dolphin (Delphinidae).<ref>Secchi, E. (2012). ''Sotalia fluviatilis''. The IUCN Red List of Threatened Species {{doi|10.2305/IUCN.UK.2012.RLTS.T190871A17583369.en}}</ref>

River dolphins have a torpedo shaped body with a flexible neck, limbs modified into flippers, non-existent external ear flaps, a tail fin, and a small bulbous head. River dolphin skulls have small eye orbits, a long snout and eyes placed on the sides of the head. River dolphins are rather small, ranging in size from the {{convert|5|ft|m|sp=us|adj=on}} long [[South Asian river dolphin]] to the {{convert|8|ft|m|sp=us|adj=on}} and {{convert|220|lbs|kg|adj=on}} [[Amazon river dolphin]]. They all have female-biased [[sexual dimorphism]] apart from Amazon river dolphin, with the females being larger than the males.<ref>{{cite book |url=http://www.cetus.ucsd.edu/SIO133/PDF/Sexual%20Dimorphism.pdf |title=Sexual Dimorphism |author1=Ralls, Katherine |author2=Mesnick, Sarah |pages=1005–1011 |access-date=2015-09-12 |archive-date=2019-07-25 |archive-url=https://web.archive.org/web/20190725004132/http://www.cetus.ucsd.edu/SIO133/PDF/Sexual%20Dimorphism.pdf |url-status=dead }}</ref><ref name="Cetacean anatomy">{{cite journal|last1=Reidenberg|first1=Joy S.|title=Anatomical adaptations of aquatic mammals|journal=The Anatomical Record|date=2007|volume= 290|issue=6|pages=507–513|doi=10.1002/ar.20541|pmid=17516440|s2cid=42133705|doi-access=free}}</ref> River dolphins are [[polygynous]], meaning male river dolphins typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them.<ref name="Cetacean anatomy"/>

River dolphins have conical teeth, used to catch swift prey such as small river fish.<ref name="Cetacean anatomy"/> They also have very long snouts, with some measuring {{convert|23|in|cm|sp=us}}, four times longer than most of their [[oceanic dolphin|oceanic counterparts]]. They have a two-chambered stomach that is similar in structure to that of terrestrial carnivores. They have [[Fundic stomach|fundic]] and [[Pyloric stomach|pyloric]] chambers.<ref>{{cite book |author1=Stevens, C. Edward |author2=Hume, Ian D. |isbn=978-0521617147|title=Comparative Physiology of the Vertebrate Digestive System |url=https://archive.org/details/comparativephysi0000stev |url-access=registration |publisher=Cambridge University Press |page=[https://archive.org/details/comparativephysi0000stev/page/317 317] |year=1995}}</ref> Breathing involves expelling stale air from their [[blowhole (anatomy)|blowhole]], followed by inhaling fresh air into their lungs. They do not have the iconic [[Blowhole_Blowhole (anatomy)|spout]], as this only forms when the warm air exhaled from the lungs meets cold external air, which does not occur in their tropical habitats.<ref name="Cetacean anatomy"/><ref>{{cite journal |last1=Scholander |first1=Per Fredrik |title=Experimental investigations on the respiratory function in diving mammals and birds |year=1940 |journal=Hvalraadets Skrifter |volume=22 |pages=1–131}}</ref>

River dolphins have two flippers and a tail fin. These flippers contain four digits. Although river dolphins do not possess fully developed hind limbs, some possess discrete rudimentary appendages, which may contain feet and digits. River dolphins are slow swimmers in comparison to oceanic dolphins, which can travel at speeds up to {{convert|35|mph|kph|sp=us}}; the [[tucuxi]] can only travel at about {{convert|14|mph|kph|sp=us}}.<ref>{{cite journal|url=http://www.bio-nica.info/biblioteca/Edwards2001.pdf|last1=Edwards|first1=Holly H.|last2=Schnell|first2=Gary D.|title=Body Length, Swimming Speed, Dive Duration, and Coloration of the Dolphin ''Sotalia fluviatilis'' (Tucuxi) in Nicaragua|journal=Caribbean Journal of Science|volume=37|pages=271–298|year=2001}}</ref> Unlike other cetaceans, their neck vertebrae are not fused together, meaning they have greater flexibility than other non-terrestrial [[aquatic mammal]]s, at the expense of speed. This means they can turn their head without actually moving their entire body.<ref>{{cite journal|url=http://acsonline.org/fact-sheets/boto-amazon-river-dolphin/|title=Boto (Amazon river dolphin) ''Inia geoffrensis''|journal=American Cetacean Society|year=2002|access-date=September 12, 2015}}</ref><ref>{{cite book|chapter-url=https://books.google.com/books?id=ASIVAAAAIAAJ&q=whales+have+a+fused+neck+vertebrae&pg=PA37|last=Tinker|first=Spencer|title=Whales of the World|chapter=The Vertebrae of the Cervical Region|page=[https://archive.org/details/whalesofworld00tink/page/37 37]|isbn=978-0-935848-47-2|date=1988-01-01|publisher=Brill Archive |url-access=registration|url=https://archive.org/details/whalesofworld00tink/page/37}}</ref> When swimming, river dolphins rely on their tail fins to propel themselves through the water. Flipper movement is continuous. River dolphins swim by moving their tail fins and lower bodies up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering. All species have a [[dorsal fin]].<ref name="Cetacean anatomy">{{cite journal|last1=Reidenberg|first1=Joy S.|title=Anatomical adaptations of aquatic mammals|journal=The Anatomical Record|date=2007|volume= 290|issue=6|pages=507–513|doi=10.1002/ar.20541|pmid=17516440|s2cid=42133705|doi-access=free}}</ref>

As China developed economically, pressure on the [[baiji|baiji river dolphin]] grew significantly.<ref name="Dolphins"/>{{rp|41–46}} [[Industrial waste|Industrial]] and residential waste flowed into the Yangtze. The riverbed was dredged and reinforced with concrete in many locations. Ship traffic multiplied, boats grew in size, and fishermen employed wider and more lethal nets. Noise pollution caused the nearly blind animal to collide with propellers. Stocks of the dolphin's prey declined drastically in the late 20th century, with some fish populations declining to one thousandth of their pre-industrial levels.<ref name=BBC>{{cite newsgroup|author=Black, Richard |url= http://news.bbc.co.uk/2/hi/science/nature/5122074.stm|title = Last Chance for China's Dolphin|date=June 27, 2006|access-date=June 27, 2006|archive-url=https://web.archive.org/web/20060706045903/http://news.bbc.co.uk/2/hi/science/nature/5122074.stm|archive-date= July 6, 2006 }}</ref> In the 1950s, the population was estimated at 6,000 animals,<ref>{{cite newsgroup|url= http://www.china.org.cn/english/environment/36657.htm|title=Rescue Plan Prepared for Yangtze River Dolphins|date=July 11, 2002|access-date=December 18, 2006}}</ref> but declined rapidly over the subsequent five decades. Only a few hundred were left by 1970. Then the number dropped down to 400 by the 1980s and then to 13 in 1997 when a full-fledged search was conducted. On December 13, 2006, the [[baiji]] (''Lipotes vexillifer'') was declared "functionally extinct", after a 45-day search by leading experts in the field failed to find a single specimen. The last verified and widely accepted sighting was in September 2004, but it has been allegedly seen and photographed by Chinese citizens on four occasions since then.<ref name=Turvey2007/><ref>{{Cite web |title=中华白鱀豚功能性灭绝十年后疑似重现长江，科考队称拍到两头_绿政公署_澎湃新闻-The Paper |url=https://m.thepaper.cn/wifiKey_detail.jsp?contid=1684992&from=wifiKey# |access-date=2024-11-13 |website=m.thepaper.cn}}</ref><ref>{{Cite web |title=The Search for the Baiji |url=https://www.theworldofchinese.com/2019/02/the-search-for-the-river-goddess/ |access-date=2024-11-13 |website=The World of Chinese |language=en}}</ref>

The region of the Amazon in Brazil has an extension of {{convert|3,100,000|mi2|km2|abbr=on|sp=us}} containing diverse fundamental ecosystems.<ref name="Silvano et al., 2009">{{cite journal|last1=Silvano|first1=R.A.M.|last2=Ramires|first2=M.|last3=Zuanon|first3=J.|title=Effects of fisheries management on fish communities in the floodplain lakes of a Brazilian Amazonian Reserve|journal=Ecology of Freshwater Fish|date=2009|volume=18|issue=1 |pages=156–166|doi=10.1111/j.1600-0633.2008.00333.x|bibcode=2009EcoFF..18..156S }}</ref><ref>{{cite journal|last1=Barletta|first1=M.|last2=Jaureguizar|first2=A.J.|last3=Baigun|first3=C.|last4=Fontoura|first4=N.F.|last5=Agostinho|first5=A.A.|last6=Almeida-Val|first6=V.M.F.|last7=Val|first7=A.L.|last8=Torres|first8=R.A.|last9=Jimenes-Segura|first9=L.F.|last10=Giarrizzo|first10=T.|last11=Fabré|first11=N.N.|last12=Batista|first12=V.S.|last13=Lasso|first13=C.|last14=Taphorn|first14=D.C.|last15=Costa|first15=M.F.|last16=Chaves|first16=P.T.|last17=Vieria|first17=J.P.|last18=Corrêa|first18=M.F.M.|title=Fish and aquatic habitat conservation in South America: A continental overview with an emphasis on Neotropical systems|journal=Journal of Fish Biology|volume=76|issue=9|pages=2118–2176|doi=10.1111/j.1095-8649.2010.02684.x|pmid=20557657|year=2010|bibcode=2010JFBio..76.2118B |url=http://repositorio.furg.br/handle/1/1948}}</ref> One of these ecosystems is a [[floodplain]], or a [[várzea forest]], and is home to a large number of fish species which are an essential resource for human consumption.<ref name="Iriarte 2013">{{cite journal|last1=Iriarte|first1=V.|last2=Marmontel|first2=M.|title=River Dolphin (''Inia geoffrensis'', ''Sotalia fluviatilis'') Mortality Events Attributed to Artisanal Fisheries in the Western Brazilian Amazon|journal=Aquatic Mammals|year=2013|volume=39|issue=2|pages=116–124|doi=10.1578/am.39.2.2013.116}}</ref> The várzea is also a major source of income through excessive local commercialized fishing.<ref name="Silvano et al., 2009"/><ref>{{cite journal|last1=Isaac|first1=V.J.|last2=Ruffino|first2=M.L.|title=Evaluation of fisheries in Middle Amazon|journal=American Fisheries Society Symposium|year=2007|volume=49|pages=587–596}}</ref><ref>{{cite book|last1=Neiland|first1=A.E.|last2=Benê|first2=C.|title=Tropical River Fisheries Valuation:Background papers to a global synthesis|year=2008|publisher=The World Fish Center|location=Penang, Malaysia|page=290}}</ref> Várzea consist of muddy river waters containing a vast number and diversity of nutrient-rich species.<ref name="171.66.127.192">{{cite journal|last1=Martin|first1=A.R.|last2=Da Silva|first2=V.M.F.|last3=Rothery|first3=P|year=2008|title=Object carrying as social–sexual display in an aquatic mammal|journal=Biology Letters|volume=4|issue=3|pages=1243–2145|doi=10.1098/rsbl.2008.0067|pmid=18364306|pmc=2610054}}</ref> The abundance of distinct fish species lures the Amazon River dolphin into the várzea areas of high water occurrences during the seasonal flooding.<ref>{{cite journal|last1=Arraut|first1=E.M.|first2=M.|last2=Marmontel|first3=J.E.|last3=Mantovani|first4=E.M.|last4=Novo|first5=D.W.|last5=Macdonald|first6=R.E.| last6=Kenward|year=2009|title=The lesser of two evils: seasonal migrations of Amazonian manatees in the Western Amazon|journal= Journal of Zoology|volume=280|number=3|pages=247–256|doi=10.1111/j.1469-7998.2009.00655.x}}</ref>

In addition to attracting predators such as the Amazon river dolphin, these high-water occurrences are an ideal location to draw in the local fisheries.<ref name="Dolphins"/>{{rp|54–58}} Human fishing activities directly compete with the dolphins for the same fish species, the [[tambaqui]] (''Colossoma macropomum'') and the [[Piaractus brachypomus|pirapitinga]] (''Piaractus brachypomus''), resulting in deliberate or unintentional catches of the Amazon river dolphin.<ref>{{cite book|last1=Reeves|first1=R.R.|last2=Smith|first2=B.D.|last3=Crespo|first3=E.A.|last4=Notarbartolo di Sciara|first4=G.|title=Dolphins, whales and porpoises: 2002–2010 conservation action plan for the world's cetaceans|year=2003|publisher=International Union for Conservation of Nature/Species Survival Committee|location=Gland, Switzerland, and Cambridge, UK|page=139}}</ref><ref name="Martin 2004">{{cite journal|last1=Martin|first1=A.R.|last2=Da Silva|first2=V.M.F.|last3=Rothery|first3=P.|title=Number, seasonal movements, and residency characteristics of river dolphins in an Amazonian floodplain lake system|journal=Canadian Journal of Zoology|date=2008|volume=82|issue=8|pages=1307–1315|doi=10.1139/z04-109}}</ref><ref name="Loch 2009">{{cite journal|last1=Loch|first1=Carolina|last2=Marmontel|first2=Miriam|last3=Simões-Lopes|first3=Paulo C.|title=Conflicts with fisheries and intentional killing of freshwater dolphins (Cetacea: Odontoceti) in the Western Brazilian Amazon|journal=Biodiversity and Conservation|date=2009|volume=18|issue=14|pages=3979–3988|doi=10.1007/s10531-009-9693-4|bibcode=2009BiCon..18.3979L |s2cid=20873255|issn=1572-9710}}</ref><ref name="Silvano et al., 2009"/><ref>{{cite book|last1=Beltrán-Pedreros|first1=S.|last2=Filgueiras-Henriques|first2=L.A.|title=Biology, evolution and conservation of river dolphins within South America and Asia|year=2010|publisher=[[Nova Science Publishers, Inc.]]|location=New York|pages=237–246}}</ref><ref name="Crespo 2010b">{{cite journal|last1=Crespo|first1=E.A.|last2=Alarcon|first2=D.|last3=Alonso|first3=M.|last4=Bazzalo|first4=M.|last5=Borobia|first5=M.|last6=Cremer|first6=M.|last7=Filla|first7=G.F.|last8=Lodi|first8=L.|last9=Magalhães|first9=F.A.|last10=Marigo|first10=J.|last11=Queiróz|first11=H.L.|last12=Reynolds|first12=J.E. III|last13=Schaeffer|first13=Y.|last14=Dorneles|first14=P.R.|last15=Lailson-Brito|first15=J.|last16=Wetzel|first16=D.L.|title=Report on the working group on major threats and conservation|journal=The Latin American Journal of Aquatic Mammals|year=2010|volume=8|issue=1–2|pages=47–56|doi=10.5597/lajam00153|doi-access=free|hdl=11336/98669|hdl-access=free}}</ref><ref name="Iriarte & Marmontel 2011">{{cite journal|last1=Iriarte|first1=V.|last2=Marmontel|first2=M.|title=Report of an encounter with a human intentionally entagled Amazon river dolphin (''Inia geoffrensis'') calf and its release in Tefé River, Amazonas State, Brazil|journal=Uakari|year=2011|volume=7|issue=2|pages=47–56}}</ref><ref name="Alves 2012">{{cite journal|last1=Alves|first1=L.C.P.S.|last2=Andriolo|first2=A.|last3=Zappes|first3=C.A.|title=Conflicts between river dolphins (Cetacea:Odontoceti) and fisheries in the Central Amazon: A path toward tragedy?|journal=Zoologia|year=2012|volume=29|issue=5|pages=420–429|doi=10.1590/s1984-46702012000500005|doi-access=free}}</ref> The local fishermen overfish, and when the Amazon river dolphins remove the commercialized fish from the nets and lines, it damages the equipment and the capture and causes a negative reaction from the local fishermen.<ref name="Loch 2009"/>

During the process of catching the commercialized fish, the Amazon river dolphins get caught in the nets and exhaust themselves until they die, or the local fishermen deliberately kill the dolphins that become entangled in their nets.<ref name="Iriarte 2013"/> The carcasses are discarded, consumed, or used as bait to attract a scavenger catfish, the [[piracatinga]] (''Calophysus macropterus'').<ref name="Iriarte 2013"/><ref name="Estupiñán">{{cite web|last1=Estupiñán|first1=G.|last2=Marmontel|first2=M.|last3=Queiroz|first3=H.L.|last4=Roberto e Souza|first4=P.|last5=Valsecchi|first5=J.|last6=da Silva Batista|first6=G.|last7=Barbosa Pereira|first7=S.|title=A pesca da piracatinga (''Calophysus macropterus'') na Reserva de Desenvolvimiento Sustentável Mamirauá [The piracatinga fishery (''Calophysus macropterus'') at Mamirauá Sustainable Development Reserve].|url=http://site-antigo.socioambiental.org/website/noticias/agenda/fks/rel_piracatinga.htm|publisher=Brazilian Ministry of Science and Technology|language=es|access-date=July 16, 2014|archive-date=July 28, 2014|archive-url=https://web.archive.org/web/20140728110821/http://site-antigo.socioambiental.org/website/noticias/agenda/fks/rel_piracatinga.htm|url-status=dead}}</ref> The use of the Amazon river dolphin carcass as bait for the piracatinga dates back from 2000.<ref name="Estupiñán"/> The increasing consumption demand by the local inhabitants and Colombia for the piracatinga has created a market for distribution of the Amazon river dolphin carcasses to be used as bait throughout these regions.<ref name="Dolphins"/>{{rp|54–58}}<ref name="Alves 2012"/>

[[File:Acuario de Valencia.JPG|thumb|upright|300px|TheOne onlyof two trained [[Amazon river dolphin]] in the world at the [[Acuario de Valencia]], Venezuela]]

[[Douglas Adams]] and [[Mark Carwardine]] documented their encounters with the endangered animals on their conservation travels for the BBC programme ''[[Last Chance to See]]''. The book by the same name, published in 1990, included pictures of a captive specimen, a male named Qi Qi (淇淇) that lived in the Wuhan Institute of Hydrobiology [[dolphinarium]] from 1980 to July 14, 2002. Discovered by a fisherman in [[Dongting Lake]], he became the sole resident of the Baiji Dolphinarium (白鱀豚水族馆) beside East Lake. A sexually mature female was captured in late 1995, but died after half a year in 1996 when the Shishou Tian-e-Zhou Baiji Semi-natural Reserve (石首半自然白鱀豚保护区), which had contained only [[finless porpoise]]s since 1990, was flooded.<ref>{{cite web|url=http://english.ihb.cas.cn/rh/rd/center13/201304/t20130418_101038.html|title=Baiji dolphinarium|author=Institute of Hydrobiology|work=Chinese Academy of Sciences|access-date=September 2, 2015|archive-date=February 3, 2022|archive-url=https://web.archive.org/web/20220203134458/http://english.ihb.cas.cn/rh/rd/center13/201304/t20130418_101038.html|url-status=dead}}</ref>

In another story, the baiji was the daughter of a general deported from the city of [[Wuhan]] during a war who ran away while her father was in duty. Later, the general met a woman who told him how her father was a general. When he realized that she was his daughter, he threw himself into the river out of shame, and his daughter ran after him and also fell into the river. Before they were drowned, the daughter was transformed into a dolphin and the general into a porpoise.<ref name=turvy>{{cite book|author=Samuel Turvy|title=Witness to Extinction: How we Failed to Save the Yangtze River Dolphin|chapter=The Goddess of the Yangtze|pages=[https://archive.org/details/witnesstoextinct0000turv/page/n20 3]–4|year=2008|publisher=Oxford University Press |isbn=978-0-19-954947-4|id={{ASIN|0199549486|country=uk}}|url=https://archive.org/details/witnesstoextinct0000turv|url-access=registration}}</ref>

[[Amazon river dolphin]]s, known by the [[Indigenous peoples of the Americas|native]]s as the [[boto]], encantados or toninastoninhas, are very prevalent in the mythology of the native South Americans. They are often characterized in mythology with superior musical ability, seductiveness and love of sex that often results in illegitimate children, and attraction to parties. Despite the fact that the Encante are said to come from a [[utopia]] full of wealth and without pain or death, the encantados crave the pleasures and hardships of human societies.<ref name=Hall>{{cite book|last=Hall|first=Jamie|chapter=Enchanted Dolphins|title=Half Human, Half Animal: Tales of Werewolves and Related Creatures|location=Bloomington, IN|year=2003|pages=55–88|isbn=978-1-4107-5809-5}}</ref>