The Black dolphin (scientific name: Cephalorhynchus eutropia), is more commonly known as the Chilean dolphin, is only found in freshwater estuaries, and coastal areas surrounding Chile. It is a marine mammal, a member of the family Delphinidae, part of the order of cetaceans. The species is so named for its black coloring on its fins, tail, and back. It is also known as the Chilean dolphin, Piebald dolphin, Southern dolphin, and White-bellied dolphin.
Because of their preference for shallow coastal waters, these dolphins are often threatened by local fisherman. This dolphin is frequently used in Chile as crab bait, as well as a food source for humans. The species population is decreasing because of this practice, and is now considered Near Threatened. Hunting restrictions have been established in Chile, however, the government has had difficulty enforcing this law in remote areas.
Resembling fellow Cephalorhynchus species, Chilean dolphins are generally described as small and chunky with lengths of about 1.65 meters for both males and females. These dolphins weigh approximately 57 kilograms, females may be slightly larger than males (slight sexual dimorphism). Chilean dolphins have a stout, torpedo-like shape and can have a girth of up to two-thirds of their length. The head is conical in shape and lacks a beak and melon. However, black dolphins have a large number of teeth: 24 to 31 on each side of each jaw.
Chilean dolphins live in the coastal waters of Chile, ranging from near Valparaiso (33°S) to south of Navarino Island (55°15'S) and as far south as Tierra del Fuego. The farthest east that this dolphin has been sighted is near the eastern mouth of the Strait of Magellan.
Biogeographic Regions: pacific ocean (Native )
The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.
Resembling fellow Cephalorhynchus species, Chilean dolphins are generally described as small and chunky with lengths of about 1.65 m for both males and females. These dolphins weigh approximately 57 kg, females may be slightly larger than males. Chilean dolphins have a stout, torpedo-like shape and can have a girth of up to two-thirds of their length. The head is conical in shape and lacks a beak and melon. The mouth line is fairly long and a groove on the sides of the face is present. The eyes are positioned just behind the mouth. The dorsal fin is low and triangular, with a long leading edge that is almost S-shaped. The flippers are rounded and medium sized. Some animals may also have serrations occurring along the edge of the flippers. Chilean dolphins are dark except for three areas of white on the throat, behind the flippers, and around the anal area. The rest of the body is a complex mix of dark tones. Areas of dark gray cover the flippers, flukes, back and dorsal fin whereas lighter gray tones cover the head and sides. The blowhole may be pale gray.
Chilean dolphins overlap in habitat with Commerson's dolphins (Cephalorhynchus commersonii). They can be distinguished by the lack of a conspicuous white area on the sides and back. Burmeister's porpoises (Phocoena spinipinnis) may also be confused, but they have more slender dorsal fins that are positioned farther back and a lower profile and more pointed peak.
Range mass: 25 to 75 kg.
Average length: 1.6 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
On Chile's convoluted coastline, Chilean dolphins prefer to live near areas of particularly strong tidal flow above a steep dropping shelf. They are most commonly found in channels and open coasts and bays. They are also found in areas of tide rips at the mouth of fjords. They prefer cold, shallow water at depths of 3 to 15 m. They may also enter rivers and estuaries and can be seen as far as 5 kilometers upstream.
Range depth: 20 to 3 m.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: rivers and streams; coastal ; brackish water
Habitat and Ecology
Most sightings have been near shore and therefore the Chilean dolphin is considered a coastal species, although there has been little survey effort in adjacent offshore waters. Movements appear quite limited, with most dolphins resident in a small area. Individuals identified from natural markings on their dorsal fins have been shown to concentrate their activities in specific bays and channels (Heinrich, 2006; F. Viddi pers. comm., April 2007). Groups tend to be small (between 2 and 15), but relatively large aggregations (20-50) also have been reported (Goodall 1994). Although mixed groups of Chilean and Peale’s dolphins have been observed, a clear pattern of spatial and temporal partitioning of coastal habitat by the two species was documented during a six-year study at Isla Grande de Chiloé (Heinrich 2006). This pattern might not apply in other areas, such as farther south in the Guaitecas Archipelago, where mixed groups are often observed foraging and socializing (F. Viddi pers. comm., April 2007).
Chilean dolphins feed on shallow-water fishes (e.g., sardines, anchovies, rock cod), cephalopods, and crustaceans (Goodall 1994).
Chilean dolphins commonly feed on small schooling fish, such as sardines (Strangomera bentincki), squid (Loligo gahi, for example), and crustaceans (such as Munida subrugosa). Chilean dolphins which have been observed near salmon hatcheries may eat young, newly released salmon.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
It is unknown how Chilean dolphins impact their ecosystem.
- Whale lice
- trematodes (Trematoda)
Chilean dolphins are agile and fast swimmers. Natural predation on Chilean dolphins has not been observed, but they may fall prey to sharks and killer whales.
Life History and Behavior
Chilean dolphins produce "cries" consisting of rapid pulses at very low levels. Recording equipment at the time was not sufficient to capture the full extent of their sounds. They use echolocation to navigate their environment.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; ultrasound ; echolocation ; chemical
Although longevity has not been determined in Chilean dolphins, the related species, Commerson's dolphins and Hector's dolphins have a lifespan of up to 20 years.
Little is known about the mating system and mating behavior of this species.
Chilean dolphins mate in the early winter and bear young in the spring. Females have one calf every two years. Sexual maturity is reached in 5 to 9 years. Other aspects of Chilean dolphin reproduction are not well understood.
Breeding interval: Females generally have one calf every two years.
Breeding season: Chilean dolphins breed in the winter.
Average number of offspring: 1.
Range age at sexual or reproductive maturity (female): 5 to 9 years.
Range age at sexual or reproductive maturity (male): 5 to 9 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Female Chilean dolphins invest heavily in young through gestation and lactation. Like other dolphins, young are likely to remain with their parents for long periods during which they learn complex social behaviors, navigation, and foraging.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female)
Chilean dolphins are listed as near threatened by the IUCN. Exact populations are difficult to measure but populations are considered in decline. Chilean dolphins have been hunted for food and as crab bait for generations. These dolphins are also accidentally caught in coastal gillnets. They also suffer from habitat encroachment by coastal salmon farming. More accurate information on Chilean dolphin populations and the threats they face is needed to formulate a conservation plan.
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: near threatened
IUCN Red List Assessment
Red List Category
Red List Criteria
Bycatch rates are poorly known, several threats in addition to bycatch have been identified, and the species has a restricted range. Therefore, it is urgent that range-wide research be conducted on the current status of this species. Re-assessment should be a high priority once better information becomes available.
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
- 1990Insufficiently Known(IUCN 1990)
- 1988Insufficiently Known(IUCN Conservation Monitoring Centre 1988)
Incidental mortality occurs throughout the range. Although no estimate exists of total incidental mortality in Chile, at Queule, south of Valdivia, Chilean dolphins accounted for nearly half of the dolphins taken in gill nets set from some 30 boats (Reyes and Oporto 1994). This would imply a catch of some 65-70 Chilean dolphins per year at this one port (Goodall 1994). An unknown number of Chilean dolphins are caught in shore-based gillnets set by local people from Isla Chiloé to capture small native fish and introduced farmed salmon that have escaped from their cages (Heinrich 2006).
Aquaculture farms for salmon and shellfish also may have negative effects on Chilean dolphins, e.g. by restricting their movements and eliminating important habitat along the east coast of Isla Grande de Chiloé. Exclusion of Chilean dolphins from bays and fjords is due mainly to large-scale shellfish farming operations but also to salmon farms, although these latter usually are located farther from shore and in deeper water than that preferred by the dolphins (Kemper et al. 2003; Heinrich 2006; Ribeiro et al. 2007). It has been shown that boat traffic, mainly related to aquaculture, affects the behaviour of Chilean dolphins (Ribeiro et al. 2005). Finally, there is evidence that Chilean dolphins are sometimes caught incidentally in anti-sea lion nets set up around salmon farms in the fjords and channels (Francisco Viddi pers. comm., April 2007).
Better information on the status of Chilean dolphins is needed. The species may be declining because of bycatch and the consequences of extensive modification of its limited habitat in Chile. Specifically, it is important to obtain abundance estimates, quantitative information on direct and incidental mortality, and better information on habitat use in relation to aquaculture and other human activities that may degrade or eliminate these dolphins’ habitat. The rapid expansion of salmon (and shellfish) farming in southern Chile is a particular concern. It is also important to evaluate possible gaps in the distribution of Chilean dolphins.
Relevance to Humans and Ecosystems
There are no known adverse effects of Chilean dolphins on humans.
Chilean dolphins have been hunted in the past for food and as bait for lucrative crab farming. Fisherman use the meat from the dolphins as bait to catch king crabs although this practice is now illegal.
Positive Impacts: food
IUCN Red List Category
The Chilean dolphin (Cephalorhynchus eutropia), also known as the black dolphin, is one of four dolphins in the genus Cephalorhynchus. The dolphin is only found off the coast of Chile; it is commonly referred to in the country as tonina.
The Chilean dolphin is small at around 1.7 m (5.6 ft) in length, with a blunt head. These characteristics often make for its incorrect identification as a porpoise. This dolphin is thickly shaped with its girth up to two-thirds its length. The dorsal fin and flippers are small in proportion to body size in comparison with other dolphins. The throat, underside, and the closest part of the flippers to the body are white. The remainder of the body is a mix of greys. It has 28-34 pairs of teeth in the upper jaw and 29-33 in the lower.
The Chilean dolphin is normally sighted in small groups of around two to 10 individuals, with some larger gatherings occasionally sighted.
Longevity, gestation, and lactation periods are not known, but are believed to be similar in length to the more studied, and similar, Hector's and Commerson's dolphins which have a gestation period of about 10 months to one year and maximum longevity of 20 years.
Population and distribution
The population of the Chilean dolphin, perhaps one of the least studied of all cetaceans, is not known with certainty. There may be as many as a few thousand individuals, although at least one researcher, Steve Leatherwood, has suggested the population may be much lower (see also  for a survey of South American cetacean population with data on the Chilean dolphin). Whatever its number, the Chilean dolphin is endemic to the coast of Chile and thought not to migrate. The dolphin is seen over a wider interval of latitudes than other Cephalorhynchus species — from Valparaíso at 33°S to Cape Horn at 55°S. The species appears to prefer areas of shallow water (less than 200 m depth) and in particular enjoys fast-flowing tidal areas and mouths of rivers.
The Chilean dolphin is listed on Appendix II 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.
In the early part of the 20th century, the Chilean dolphin was commonly known as the black dolphin. This was later agreed to be a poor choice of name. Most of the few individual specimens studied by scientists were either washed-up individuals whose skin had darkened due to exposure to air or live specimens seen at sea but only at a distance (and so appeared darker than they were). As more specimens were studied, it became clear that the back of the dolphin was in fact a mixture of grey colours and that its underside was white. The scientific community is now universally agreed in naming the dolphin Chilean on account of its distribution along the coast of the country.
- Reeves, R.R., Crespo, E.A., Dans, Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Pedraza, S., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, JY. & Zhou, K. (2008). "Cephalorhynchus eutropia". IUCN Red List of Threatened Species. Version 2012.2. International Union for Conservation of Nature. Retrieved 18 January 2013.
- Chilean Dolphin Spanish site promoting conservation and awareness of this species.[dead link]
- "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.
- Convention on Migratory Species page on the Chilean dolphin