Peale's dolphin (''Lagenorhynchus australis'') is a small
dolphin
A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...
found in the waters around
Tierra del Fuego
Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla ...
at the foot of
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...
. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, since Rice's work Peale's dolphin has been adopted as the standard common name.
Taxonomy
Though it is traditionally placed in the genus ''Lagenorhynchus'', recent
molecular analyses indicate Peale's dolphin is actually more closely related to the dolphins of the genus ''
Cephalorhynchus
''Cephalorhynchus'' is a genus in the dolphin family Delphinidae.
Extant species
It consists of four species:
The species have similar physical features—they are small, generally playful, blunt-nosed dolphins—but they are found in di ...
''. If true, this would mean this species must either be transferred to ''Cephalorhynchus'' or be given a new genus of its own. An alternate genus proposed for this species (as well as the
Pacific white-sided dolphin
The Pacific white-sided dolphin (''Lagenorhynchus obliquidens''), also known as the hookfin porpoise, is an active dolphin found in the cool or temperate waters of the North Pacific Ocean.
Taxonomy
The Pacific white-sided dolphin was named by Sm ...
,
hourglass dolphin
The hourglass dolphin (''Lagenorhynchus cruciger'') is a small dolphin in the family Delphinidae that inhabits offshore Antarctic and sub-Antarctic waters. It is commonly seen from ships crossing the Drake Passage, but has a circumpolar dis ...
and
dusky dolphin
The dusky dolphin (''Lagenorhynchus obscurus'') is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, b ...
is the resurrected genus ''
Sagmatias''.
Some behavioral and morphological data support moving Peale's dolphin to ''Cephalorhynchus''. According to , 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.
Physical description
Peale's dolphin is of typical size in its family — about 1 m in length at birth and 2.1 m (6.9 ft) when fully mature. Its adult weight is about 115 kg. 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 under just behind each flippers. These are known as the "armpits". The flanks also have a large white-grey patch above the flipper. The
dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...
is large for this size
cetacean and distinctively falcated. 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
Peale's dolphin is endemic to the coastal waters around southern
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...
. On the Pacific side, they have been seen as far north as
Valdivia
Valdivia (; Mapuche: Ainil) is a city and commune in southern Chile, administered by the Municipality of Valdivia. The city is named after its founder Pedro de Valdivia and is located at the confluence of the Calle-Calle, Valdivia, and Cau-Cau R ...
,
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
at
38°S. On the Atlantic side, sightings typically diminish at about
44°S — near
Golfo San Jorge
The San Jorge Gulf (Golfo San Jorge; Spanish for ''Gulf of St. George'') is a bay in southern Patagonia, Argentina. It is an ocean basin opening to the Atlantic. Its shoreline spans Chubut and Santa Cruz province. The gulf measures approximatel ...
,
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
. In the south, they have been seen at almost
60°S — well into the
Drake Passage
The Drake Passage (referred to as Mar de Hoces Hoces Sea"in Spanish-speaking countries) is the body of water between South America's Cape Horn, Chile and the South Shetland Islands of Antarctica. It connects the southwestern part of the Atla ...
.
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.
Behaviour
Peale's dolphins congregate in small groups — usually about five in number, and sometimes up to 20.
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.
Peale's dolphins are often found swimming slowly near kelp beds.
They have been found to associate with other cetaceans such as Commerson's dolphins.
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 also 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.
[Berta, Annalisa, editor. ''Whales, Dolphins & Porpoises: A Natural History and Species Guide''. University of Chicago Press, 2015.]
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 fisherman killed and used thousands of Peale's dolphins for crab bait each year.
This practice has decreased, but not been made illegal.
In Argentina, Peale's dolphins have been reported becoming trapped in gill nets, but the extent of this is not known.
Conservation groups such as the
Whale and Dolphin Conservation
Whale and Dolphin Conservation (WDC), formerly Whale and Dolphin Conservation Society in the UK, is a wildlife charity that is dedicated solely to the worldwide conservation and welfare of all whales, dolphins and porpoises ( cetaceans). It h ...
demand further research be made into this species.
The Peale's dolphin or black-chinned dolphin is listed on Appendix II
[Appendix II]
" 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. of the Convention on the Conservation of Migratory Species of Wild Animals (
CMS
CMS may refer to:
Computing
* Call management system
* CMS-2 (programming language), used by the United States Navy
* Code Morphing Software, a technology used by Transmeta
* Collection management system for a museum collection
* Color manag ...
). 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.
Convention on Migratory Species page on the Peale's dolphin / Black-chinned dolphin
/ref>
See also
*List of cetaceans
Cetacea is an infraorder that comprises the 94 species of whales, dolphins, and porpoises. It is divided into toothed whales (Odontoceti) and baleen whales (Mysticeti), which diverged from each other in the Eocene some 50 million years ago (m ...
* Marine biology
References
*''National Audubon Society: Guide to Marine Mammals of the World''
*''Encyclopedia of Marine Mammals''
*
*
*
{{Taxonbar, from=Q300991
Mammals of Argentina
Mammals of Chile
Mammals of Patagonia
Marine fauna of South America
Fauna of Tierra del Fuego
Peale's dolphin
Taxa named by Titian Peale
Taxobox binomials not recognized by IUCN
Lagenorhynchus