Chilean dolphin (Cephalorhynchus eutropia)

Description

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Chilean dolphin fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Chilean dolphin description

The Chilean dolphin (Cephalorhynchus eutropia) is a little known species with a relatively small distribution ^{(1) (2)}. Small and stocky like the other members of the genus, it has a poorly defined beak, rounded flippers, and a comparatively large, rounded dorsal fin ^{(2) (4) (5)}. Dorsally, it is essentially grey in colour ^{(4) (5)}, with a lighter grey-cap over the melon ⁽²⁾. The belly and throat are mostly white and behind each flipper there is an oval white patch ⁽²⁾. A dark band across the throat, often shaped like a rhombus in the middle, links the flippers ^{(2) (5)}.

Also known as

Black dolphin, white-bellied dolphin.

French

Dauphin Du Chili.

Spanish

Delfín Chileno, Delfín Negro, Tunina De Vientre Blanco.

Size

Length: 1.7 m ⁽²⁾

Weight

60 kg ⁽²⁾

Chilean dolphin biology

Owing to its apparent shyness and relative scarcity, little is known about the Chilean Dolphin ^{(1) (4) (5)}. Small groups comprising two to fifteen dolphins are most common, but larger groups of up to 400 have been reported in the northern part of its range ^{(1) (5)}. It is probably an opportunistic hunter, feeding mainly on crustaceans, cephalopods, and shallow water fishes such as sardines, anchovies and rock cod ^{(1) (2) (5)}.

Nothing is known about the seasonal movements of this species, but most Chilean dolphins appear to remain resident in a small area ^{(1) (2) (5)}. Similarly, very little is known about its reproductive biology, other than that young dolphins are more commonly sighted between October and April ^{(4) (5)}.

Chilean dolphin range

As its name suggests, the Chilean Dolphin occurs along the coast of Chile from 30 degrees south to Cape Horn at the southern tip of South America, where it is possibly also found in Argentinean waters ⁽¹⁾.

Chilean dolphin habitat

The Chilean dolphin is generally found in cold, shallow, coastal waters, where it readily enters estuaries and rivers. Areas with rapid tidal flow or strong rips seem to be preferred ^{(1) (2)}.

Chilean dolphin status

The Chilean dolphin is classified as Near Threatened (NT) on the IUCN Red List ⁽¹⁾ and listed on Appendix II of CITES ⁽²⁾.

Chilean dolphin threats

For many years, the Chilean dolphin has been hunted for crab bait and allegedly also for food. With the number of mature individuals almost certainly numbering less than 10,000, hunting of this species for bait presents a considerable threat to its long-term survival. Despite the killing of dolphins being legally prohibited, law enforcement is difficult in remote areas, while an unknown, but probably substantial number are taken as bycatch in other fisheries ^{(1) (2)}. An additional concern is the rapid expansion of salmon and shellfish farms, which exclude Chilean dolphins from important areas of habitat and restrict movement ⁽¹⁾.

Chilean dolphin conservation

Given the paucity of information on the Chilean dolphin, the main priority is to conduct range-wide research so that an accurate assessment of its conservation status can be made. In particular, it is vital to obtain information on its population, the scale of direct and incidental mortality, and the impact of habitat degradation associated with aquaculture and other human activities ⁽¹⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For further information on the conservation of dolphins: 

• Whale and Dolphin Conservation Society:
  www.wdcs.org

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Glossary

Aquaculture

The cultivation of marine or freshwater food fish or shellfish under controlled conditions.

Bycatch

In the fishing industry, the part of the catch made up of non-target species.

Cephalopods

From the Greek for ‘head-foot’, a class of molluscs that occur only in marine habitats. All species have grasping tentacles, and either an internal or external shell. Includes nautiloids, cuttlefish, squids, octopuses, and extinct ammonites and belemnites.

Crustaceans

Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.

Dorsal fin

In fish, the unpaired fin found on the back of the body.

Melon

Waxy lens-shaped structure in the forehead, which focuses the sounds produced in the nasal passage.

References

1. IUCN Red List (June, 2009)
   http://www.iucnredlist.org/
2. Convention on Migratory Species (June, 2009)
   http://www.cms.int/reports/small_cetaceans/data/c_eutropia/c_eutropia.htm
3. Jefferson, T.A., Webber, M.A. and Pitman, R.L. (2008) Marine mammals of the world: a comprehensive guide to their identification. Academic Press, San Diego, California.
4. Martin, A.R. (1990) Whales and Dolphins. Salamander Books, London.