Peale's dolphin
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Peale's dolphin (Cephalorhynchus australis) is a small dolphin found in the waters around Tierra del Fuego at the foot of South America. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, since Rice's work <ref>"Marine Mammals of the World. Systematics and Distribution", by Dale W. Rice (1998). Published by the Society of Marine Mammalogy as Special Publication No. 4</ref> Peale's dolphin has been adopted as the standard common name.
Taxonomy
Though it had traditionally been placed in the genus Lagenorhynchus, molecular analyses indicated Peale's dolphin is more closely related to the dolphins of the genus Cephalorhynchus. Some behavioral and morphological data supported moving Peale's dolphin to Cephalorhynchus.<ref>Template:Cite journal</ref> According to Template:Harvnb, Peale's dolphin and the Cephalorhynchus species are the only dolphins that do not whistle. Peale's dolphin also shares with several Cephalorhynchus species the possession of a distinct white "armpit" marking behind the pectoral fin. As a result, Peale's dolphin was reclassified as Cephalorhynchus australis in 2025.<ref>Template:Cite web</ref>
Physical description
Peale's dolphin is of typical size in its family — about Template:Cvt in length at birth and Template:Cvt when fully mature. Its adult weight is about Template:Cvt. It has a dark-grey face and chin. The back is largely black with a single off-white stripe running, curving, and thickened as it runs down the back on each side. The belly is white. Conspicuously, also, a white patch occurs just behind each flipper. These are known as the "armpits". The flanks also have a large white-grey patch above the flipper. The dorsal fin is large for this size cetacean and distinctively falcate. The flippers themselves are small and pointed. The tail fin, too, has pointed tips, as well as a notch at its middle.
The species looks similar to the dusky dolphin when viewed at a distance, and may be confused with it.
Population and distribution
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Peale's dolphin is endemic to the coastal waters around southern South America. On the Pacific side, they have been seen as far north as Valdivia, Chile, at 38°S. On the Atlantic side, sightings typically diminish at about 44°S — near Golfo San Jorge, Argentina. In the south, they have been seen at almost 60°S — well into the Drake Passage.
They are often found in areas of fast-moving waters, such as entrances to channels and narrows, as well as close to shore in safe areas such as bays.
The total population is unknown, but recent research estimates there to be ~21,800 individuals in the South Atlantic part of its range.<ref name="iucn"/>
Behaviour
Peale's dolphins congregate in small groups, usually about five, and sometimes up to 20.<ref name=":1">Template:Cite book</ref> On rare occasions in summer and autumn, much larger groups have been recorded (100 individuals). A typical pattern is for the group to move in a line parallel to the shore. They usually swim slowly, but are prone to bursts of activity.<ref name="iucn" />
Peale's dolphins are often found swimming slowly near kelp beds.<ref name=":1" /><ref name=":2" /> They have been found to associate with other cetaceans, such as Commerson's dolphins.<ref name=":2" />
Using underwater acoustic recordings, it has been shown that Peale's dolphins can produce both broadband clicks and tonal whistles, along with the usual NBHF clicks produced by other whistling Odontoceti species.<ref>Template:Cite journal</ref>
Food and foraging
In the southwestern South Atlantic, Peale's dolphin forages in the coastal ecosystem, feeding mainly on the demersal and bottom fish such as southern cod and Patagonian grenadier; also, octopus, squid, and shrimps have been found in stomachs examined. They feed in or near kelp beds and in open waters, with cooperative feeding, such as straight-line and large circle formations or star-burst feeding in which large groups encircle prey.<ref name=":2">Berta, Annalisa, editor. Whales, Dolphins & Porpoises: A Natural History and Species Guide. University of Chicago Press, 2015.</ref>
Conservation
Peale's dolphins' propensity for moving over only small areas and staying close to shore has rendered them vulnerable to interference by man. During the 1970s and '80s, Chilean fishermen killed and used thousands of Peale's dolphins for crab bait each year.<ref name="iucn" /><ref name=":2" /> This practice has decreased, but has not been made illegal.<ref name="iucn" /><ref name=":2" />
In Argentina, Peale's dolphins have been reported becoming trapped in gill nets, but the extent of this is not known.<ref name="iucn" /> Conservation groups such as the Whale and Dolphin Conservation demand further research be made into this species.
The Peale's dolphin or black-chinned dolphin is listed on Appendix II<ref name="Appendices">"Appendix II Template:Webarchive" 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.</ref> of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II<ref name="Appendices" /> as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.<ref>Template:Cite web</ref>
See also
References
- National Audubon Society: Guide to Marine Mammals of the World Template:ISBN
- Encyclopedia of Marine Mammals Template:ISBN
- Template:Cite journal
- Template:Cite journal
- Template:Cite journal