Peale's Dolphin
Encyclopedia
Peale's Dolphin 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 Peale's Dolphin has been adopted as the standard common name.
analyses indicate that Peale's Dolphin is actually more closely related to the dolphins of the genus Cephalorhynchus
. If true, this would mean that this species must either be transferred to Cephalorhynchus or be given a new genus of their own. An alternate genus that has been proposed for this species (as well as the Pacific White-sided Dolphin
and Dusky Dolphin
is Sagmatias
. There is some behavioral and morphological to support moving Peal's Dolphin to Cephalorhynchus. According to Schevill & Watkins (1971), 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.
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.
. On the Pacific side they have been seen as far north as Valdivia
, Chile
at 38° S. On the Atlantic side sightings typically peter out 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 is thought to be locally common.
In Argentina there have been reports of Peale's Dolphins becoming trapped in gillnets but the extent of this is not known. Conservation groups such as the Whale and Dolphin Conservation Society demand further research be made into this species.
The Peale's dolphin or Black-chinned dolphin is listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS
). 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.
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
found in the waters around Tierra del Fuego
Tierra del Fuego
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
at the foot of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. 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 molecularMolecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
analyses indicate that Peale's Dolphin is actually more closely related to the dolphins of the genus Cephalorhynchus
Cephalorhynchus
Cephalorhynchus is a genus in the dolphin family Delphinidae. It consists of four species:*Commerson's Dolphin, Cephalorhyncus commersonii*Chilean Dolphin, Cephalorhyncus eutropia*Heaviside's Dolphin, Cephalorhyncus heavisidii...
. If true, this would mean that this species must either be transferred to Cephalorhynchus or be given a new genus of their own. An alternate genus that has been proposed for this species (as well as the Pacific White-sided Dolphin
Pacific White-sided Dolphin
The Pacific White-sided Dolphin is a very active dolphin found in the cool to temperate waters of the North Pacific Ocean.-Taxonomy:...
and Dusky Dolphin
Dusky Dolphin
The dusky dolphin 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, but current scientific consensus is that they are distinct species...
is Sagmatias
Sagmatias
Sagmatias is a genus that has been proposed for certain dolphin species that are currently placed in the genus Lagenorhynchus. Mitochondrial DNA studies have indicated that certain dolphin species within Lagenorhynchus are actually more closely related to dolphins within the genus Cephalorhynchus...
. There is some behavioral and morphological to support moving Peal's Dolphin to Cephalorhynchus. According to Schevill & Watkins (1971), 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 1m in length at birth and 2.1m 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 there is also a white patch 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 finDorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
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
Dusky Dolphin
The dusky dolphin 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, but current scientific consensus is that they are distinct species...
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 AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. On the Pacific side they have been seen as far north as Valdivia
Valdivia River
The Valdivia River or Río Valdivia, as it is known locally, is a major river in southern Chile. It is the continuation of the Calle-Calle River, from the point where it meets the Cau-Cau River in the city of Valdivia. The Valdivia river ends in Corral Bay, on the Pacific coast. Other tributaries...
, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
at 38° S. On the Atlantic side sightings typically peter out at about 44° S - near Golfo San Jorge, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. In the south they have been seen at almost 60° S - well into the Drake Passage
Drake Passage
The Drake Passage or Mar de Hoces—Sea of Hoces—is the body of water between the southern tip of South America at Cape Horn, Chile and the South Shetland Islands of Antarctica...
.
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 is thought to be locally common.
Behaviour
Peale's Dolphins congregate in small groups - usually about 5 in size 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.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 tailed off but not been made illegal.In Argentina there have been reports of Peale's Dolphins becoming trapped in gillnets but the extent of this is not known. Conservation groups such as the Whale and Dolphin Conservation Society demand further research be made into this species.
The Peale's dolphin or Black-chinned dolphin is listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS
Bonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
). 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.