La Plata dolphin
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|La Plata dolphin|
|Illstration from 1847|
|Size compared to an average human|
Gervais & d'Orbigny, 1844
|La Plata dolphin range|
The La Plata dolphin or Franciscana (Pontoporia blainvillei) is found in coastal Atlantic waters of southeastern South America. It is a member of the river dolphin group and the only one that lives in the ocean and saltwater estuaries, rather than inhabiting exclusively freshwater systems.
The La Plata dolphin is the only species in its genus and is often placed in its own family, the Pontoporiidae. It was first described by Paul Gervais and Alcide d'Orbigny in 1844 (the species epithet blainvillei commemorates the French zoologist Henri Marie Ducrotay de Blainville). The La Plata dolphin is also widely known as the Franciscana - the Argentine and Uruguay a name that has been adopted internationally. Other common names are the toninha (the Brazilian name) and cachimbo.
The La Plata dolphin has the longest beak (as a proportion of body size) of any cetacean — as much as 15% in older adults. Males grow to 1.6 metres (5.2 ft) and females to 1.8 metres (5.9 ft). The body is a greyish brown colour, with a lighter underside. The flippers are also very large in comparison with body size and are very broad, but narrow on joining the body, so are almost triangular in shape. The trailing edges are serrated. The crescent-shaped blowhole lies just in front of a crease in the neck, giving the impression that dolphin forever has its head cricked upwards. The dorsal fin has a long base and a rounded tip.
The La Plata dolphin weighs up to 50 kilograms (110 lb), and lives for up to 20 years. The gestation period is around 10–11 months and juveniles take just a few years to mature. Females may be giving birth by the age of five.
Behavior and feeding
The animal is very inconspicuous—it moves very smoothly and slowly—and can be difficult to spot unless estuary conditions are very calm. It will commonly swim alone or in small groups. Exceptional groups as large as 15 have been seen. La Plata dolphins are bottom feeders and gut inspections have revealed they eat at least 24 different species of fish, depending on which species are most common. They will also take octopus, squid and shrimp. They are, in turn, hunted by killer whales (orcas) and several species of sharks.
Range and habitat
The La Plata dolphin is found in the coastal Atlantic waters of southeastern South America, including the Río de la Plata estuary. Its distribution ranges from the Tropic of Capricorn near Ubatuba, Brazil, south to Península Valdés, Argentina. It is the only member of the river dolphin group that lives in the ocean and saltwater estuaries, rather than freshwater. Although some members of the species do spend portions of their lives outside of river systems, many individuals live their entire lives within rivers, never venturing into the ocean proper.
The La Plata dolphin is affected by factors like habitat destruction and water pollution. Plastic debris and synthetic material has been found in the stomach contents of these animals. More research is necessary to determine whether or not these factors negatively affect the health of La Plata dolphins.  90% of the population in Guanabara Bay was lost in three decades.
The La Plata dolphin is listed as "Vulnerable" in the IUCN Red List of Threatened Species. However, the Franciscana is a particular conservation concern because of its restricted distribution and vulnerability to incidental capture in fishing gear. Large numbers are killed in gillnets. Although the largest documented catches in the 1970s were in Uruguay, catches in recent decades have also been high in southern Brazil and Argentina. Scientists from all three countries have voiced their concerns, and asked for international assistance in highlighting the plight of the dolphin (see Reeves et al., pg. 53).
The species is listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of its range. CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
A young La Plata dolphin was rescued in 2011 off Montevideo, Uruguay. In February 2016 a young dolphin died on the beach of Santa Teresita, Argentina. Reports circulated internationally that the dolphin's death resulted after being passed around by a crowd who were posing for selfies with it. However, an interview by the photographer of the images, Hernan Coria, contradicting such claim.
- Reeves, R.; Dalebout, M.; Jefferson, T.A.; Karkzmarski, L.; Laidre, K.; O’Corry-Crowe, G.; Rojas-Bracho, L.; Secchi, E.; Slooten, E.; Smith, B.D.; et al. (2012). "Pontoporia blainvillei". IUCN Red List of Threatened Species. Version 2012.2. International Union for Conservation of Nature. Retrieved 18 January 2013. Database entry includes a brief justification of why this species is of vulnerable.
- "Pontoporia blainvillei (Franciscana, La Plata River Dolphin)". www.iucnredlist.org. Retrieved 2016-11-27.
- Dale J.. 2016. População de golfinhos da Baía de Guanabara sofre redução de 90% em três décadas. Globo.com. Retrieved on Septem8er 18, 2017
- "Appendix I and Appendix II Archived 11 June 2011 at the Wayback Machine." of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.
- Stopera, Matt (19 October 2011). "Insanely Cute Pictures Of A Man Taking Care Of An Orphaned Baby Dolphin". Buzzfeed. Reuters. Retrieved 20 February 2016.
- Hassan, Carma; Franco, Lynn (18 February 2016). "Outrage after dolphin beach death". CNN.com.
- Brice, Chloe (19 February 2016). "Tiny dolphin killed by crowd of beachgoers for selfie in Argentina". ABC News. Retrieved 20 February 2016.
- Nagesh, Ashitha (19 February 2016). "Apparently that dolphin WASN'T killed by tourists taking selfies". Metro.co.uk. Retrieved August 19, 2016.
According to an interview Hernan Coria did with Argentinian news outlet Telefe Noticias, the baby Franciscana dolphin was one of many corpses that washed up on the beach.
- Reeves, Randall R.; Smith, Brian D.; Crespo, Enrique A.; Notarbartolo di Sciara, Giuseppe (2003), "Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans" (PDF), IUCN.org, International Union for Conservation of Nature, The World Conservation Union
- Franciscana / La Plata Dolphin at Convention on Migratory Species