Commerson's dolphins generally do not live more than 10 years in the wild. In captivity, they commonly live to 18 years of age, and one individual at SeaWorld San Diego lived to be 25.8 years of age.
Range lifespan
Status: wild: 23 (high) years.
Range lifespan
Status: captivity: 25.8 (high) years.
Typical lifespan
Status: wild: 10 (high) years.
Typical lifespan
Status: captivity: 15 to 18 years.
The black and white coloration patterns of Commerson's dolphins breaks up the outline of their body, making them more difficult for predators to spot. Natural predators may include killer whales, sharks, and leopard seals that live within the same geographic range, but such predation has not been documented. Humans actively kill Commerson's dolphins for food, oil and bait and inadvertently through other fishing practices.
Known Predators:
Anti-predator Adaptations: cryptic
Commerson's dolphins are mostly white and have black marked faces and bodies. This black and white pattern varies with geographic location as well as age and sex. These colors are more muted in coastal waters. The black color on the head extends behind the blowhole and down the sides of the body, including the flippers. Black also covers the dorsal fin and runs back to encircle the tailstock behind the anus and flukes. The black color on the chest ends in a posterior-facing point. Large black genital patches are oval or heart-shaped, with the narrow end pointing posteriorly in males. In females the narrow end is anterior, and may or may not include "ears" outside the mammary slits. The throat is generally white, as is the rest of the body. Individuals can be recognized by varying shape of the black "widow's peak" behind the blowhole as well as pigmentation on the side of the tailstock. Calves are born dark grey and black with vertical creasing as a result of fetal folding. These folds disappear after a week, and the dark grey portions become paler in the first few months and white within 4 to 6 months.
Coloration of Commerson's dolphins near Kerguelen Island is similiar to that of juveniles from the south Atlantic Ocean. Near Kerguelen, the surface in front of the dorsal fin is grey, as are the sides. The grey behind the blowhole is streaked with black and their "widow's peak" is not as well defined. The white throat patch is more asymmetrical than in individuals from the south Atlantic. Commerson's dolphins near Kerguelen generally have a narrow white line in the center of their chest, a feature seldom found in their counterparts in the south Atlantic Ocean.
Commerson's dolphins have a dark rounded dorsal fin that rises at a shallow angle and flippers with rounded tips. Their head is blunt and has a sloped forehead and little or no beak. A narrow cap extends on the rear half of body from dorsal fin to flukes. The tail flukes are slightly round tipped and notched, and the flippers are small and rounded. The flukes have concave edges with a slight hatch in the middle with dark coloring above and below. Commerson's dolphins have approximately 29 to 30 pairs of pointed teeth in the upper and lower jaws. Newborns range from 0.5 to 0.75 m in length and weigh 4.5 to 7.3 kg. Adults range from 1.2 to 1.5 meters in length and usually weigh 35 to 65 kg. Females are generally larger than males, and Commerson's dolphins from the Indian Ocean tend to be larger than those in the South Atlantic. Also, although Commerson's dolphins from both areas do not have well defined snouts, there is a distinct rostral depression in Kerguelen animals which individuals in the south Atlantic lack.
Range mass: 35 to 65 kg.
Range length: 1.2 to 1.5 m.
Sexual Dimorphism: female larger; sexes colored or patterned differently
Other Physical Features: endothermic ; bilateral symmetry
Commerson's dolphins inhabit shallow, inshore waters along coastlines, harbors, bays, and river mouths. The live in cold shallow waters, with temperatures ranging from 1˚ C to 16˚ C. They are rarely found at depths greater than 200 m. Commerson's dolphins prefer a neritic environment and are seldom found far offshore. Most sightings occur in the coastal regions near the mouths of bays and estuaries or over the wide shallow continental shelf where the tidal range is great. Commerson's dolphins move towards the shore with the tide. In some areas, dolphins prefer areas with the strongest currents - up to or greater than 15 km/hr. They are also frequently found in kelp beds and in narrow passages like those found in the Strait of Magellan. It is thought that most dolphins seasonally move away from the shore, following fish which move offshore during the winter. Commerson's dolphins in Kerguelen follow this trend and are less common inshore between June and December. In Kerguelen, they are most commonly observed over the Kerguelen shelf, but they are also found in open waters, kelp-ringed coastlines, and protected areas between islets.
Range depth: 200 (high) m.
Habitat Regions: temperate ; saltwater or marine ; freshwater
Aquatic Biomes: pelagic ; benthic ; rivers and streams; coastal
Commerson's dolphins are primarily found in the coastal waters of the southwest Atlantic Ocean near Patagonia, Tierra del Fuego, Cape Horn and the Falklands Islands. They are most commonly seen along the eastern coast of South American between 41˚30' S and 55˚ S latitude, though they have been found as far north as 31˚ S latitude in some areas.
There is also a disjunct population of Commerson's dolphins in the south Indian Ocean near Kerguelen Island. In this area, they range from 48˚30' S to 49˚45' S latitude and are most common around the Golfe du Morbihan and around Heard Island. They are the only common cetacean in these coastal waters.
Biogeographic Regions: neotropical (Native ); indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Commerson's dolphins are primarily carnivores but are often opportunistic coastal feeders. They rely on both pelagic and benthic prey. Their diet is mainly composed of mysid shrimp, and small fish like silversides, sardines, and Argentine hake. They are also known to eat squid, octopus, marine worms, tunicates, and even algae. Among 53 Commerson's dolphins in the Tierra del Fuego, 22.5% of their diet was composed of mysid shrimp, 20.4% of 3 species of fish, 14.1% of squid, and the rest of algea, isopods, and other benthic invertebrates. Other plant remains, seeds, sand, and pebbles were also found in their stomachs. Individuals found near the Kerguelen Island eat a high proportion of semipelagic chaennichthyid fish, as well as pelagic and benthic crustaceans. At times, Commerson's dolphins hunt together, as described in the behavior section. In captivity, Commerson's Dolphins consume 3 to 4 kg of Atlantic herring each day.
In areas of high tides, Commerson's dolphins feed in the shallow areas in or just beyond the advancing tide breakers in order to take fish, such as sardines and anchovies that are also feeding in the area, or other organisms that are dislodged by the turbulent water. Commerson's dolphins also feed for long periods in kelp beds, in open waters, around submarine banks, and near artificial structures such as piers and oil rigs.
Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans
Plant Foods: algae
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
Commerson's dolphins prey on small fish, mysid shrimp, as well as squid, octopus, marine worms, and tunicates. While natural predators are still unknown, killer whales and leopard seals may prey on them as they are found in the same geological area. Commerson's dolphins also act as hosts for roundworms (Nematoda) and flukes (Trematoda).
Commensal/Parasitic Species:
Humans living in Patagonia and Tierra del Fuego have traditionally harpooned Commerson's dolphins for their meat and oil. Crab fishermen in southern Argentina and Chile use the meat of Commerson's dolphins as bait, as it does not deteriorate in salt water. These practices are now illegal and have steadily declined. Commerson's dolphins can also be found in aquariums in Germany, Japan and the United States.
Positive Impacts: food ; ecotourism
Commerson's dolphins may affect fishermen, as they sometimes become entangled in fishing nets and may also deplete populations of small fish.
Commerson's dolphins were hunted for their meat and oil and more recently for crab bait. Although these practices are now illegal, they are often entangled in gillnets and other fishing gear used in nearshore waters and are occasionally killed in midwater trawl nets used for shrimp. In Tierra del Fuego alone, at least 5 to 30 dolphins die each year as by-catch in nets set perpendicular to the shore.
Near Kerguelen Island, low levels of chlorinated hydrocarbons (DDT, PCB and HCB) were found in the blubber of Commerson's dolphins, confirming the presence of pollutants in oceans far from their main source. The levels of contaminants were 10 to 100 times that of cetaceans in the North Atlantic.
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: data deficient
Commerson's dolphins communicate using echolocation. They also rely on echolocation to navigate and hunt through dark waters. In captivity, they vocalize at frequencies ranging from 120 to 134 kHz for a duration of 180 to 600 μs.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: choruses ; vibrations
Perception Channels: visual ; infrared/heat ; tactile ; acoustic ; ultrasound ; echolocation ; vibrations ; chemical
Little information is available regarding the mating systems of Commerson's dolphins. They have been observed copulating in a vertical, belly to belly position.
Commerson's dolphins breed between the months of September and February. After a gestation period of at most 12 months, females give birth to one individual in the winter. Calves are born tail first and are grey in color. Newborns range from 0.5 to 0.75 m in length and weigh 4.5 to 7.3 kg. Their dorsal fin and tail flukes are pliable at birth and gradually stiffen as they mature. The length of the nursing period in the wild is unknown. However, in captivity calves begin eating solid food by 2 months of age and take whole fish by 4 months. Males typically reach sexual maturity between 6 and 9 years of age, and females between 5 and 9 years. Individuals from the the south Atlantic Ocean, however, tend to reach sexual maturity at a younger age than populations from Kerguelen.
Breeding interval: Commerson's dolphins breed once yearly.
Breeding season: Mating occurs between late September and early February.
Range number of offspring: 1 (high) .
Range gestation period: 10 to 12 months.
Range age at sexual or reproductive maturity (female): 5 to 8 years.
Range age at sexual or reproductive maturity (male): 6 to 9 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 6600 g.
Average number of offspring: 1.
Mother Commerson's dolphins nurse their calves through abdominal mammary slits for about 9 months. Mothers are attentive to their calves, which swim close to their mother. Calves learn to swim by following in their mother's slip stream. Females also appear defensive of their young.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
Commerson's Dolphins are found in cold shore water along open coasts, in shelter fjords, bays, harbours and river mouths, and occasionnaly the lower reaches of rivers. Ther prefer he areas with strongest current such as Primera and Segunda Angostura. It also prefer areas where the continental shelfis wide and flat, the tidal range is great and te temperatures are influenced by the cool Malvinas Current.
Commerson's dolphin (Cephalorhynchus commersonii), also referred to by the common names jacobita, skunk dolphin, piebald dolphin, panda dolphin, or tonina overa (in South America), is a small oceanic dolphin of the genus Cephalorhynchus. Commerson's dolphin has two geographically-isolated but locally-common subspecies. The principal subspecies, C.c.commersonii, has sharply-delineated black-and-white patterning and is found around the tip of South America. The secondary subspecies, C.c.kerguelenensis, is larger than C.c.commersonii, has a less-sharply delineated dark and light grey patterning with a white ventral band, and is found around the Kerguelen Islands in the Indian Ocean.
The dolphin is named after French naturalist Dr Philibert Commerson, who first described them in 1767 after sighting them in the Strait of Magellan.[4]
Two disjunct subspecies of the dolphin are found in geographically disparate areas separated by 130° of longitude and about 8,500 km (5,300 mi); it is not known why they are thus distributed. Global populations are unknown, but the species is accepted to be locally common.[5]
The main subspecies, C.c.commersonii, is found inshore in various inlets in Argentina including Puerto Deseado, in the Strait of Magellan and around Tierra del Fuego, and near the Falkland Islands (Las Malvinas).[6] A survey in 1984 estimated there to be 3,200 individuals in the Strait of Magellan. [7]
Dolphins of the second subspecies, C.c.kerguelenensis, were discovered in the 1950s. They reside near the Kerguelen Islands in the southern part of the Indian Ocean, and prefer shallow waters.
In 2004, a vagrant individual of unconfirmed origin was sighted on South Africa's Agulhas Bank, a location 4,200 km (2,600 mi) from the Kerguelen Islands and 6,300 km (3,900 mi) from South America. Though the Kerguelen Islands are closer, such a journey would require swimming against the Antarctic Circumpolar Current.[8]
The commersonii subspecies has a black head, dorsal fin, and fluke, with a white throat and body. The demarcation between the two colours is very clear-cut. This stocky creature is one of the smallest of all cetaceans, growing to around 1.5 m (5 ft). A mature female caught off of southern Patagonia, at 23 kg (51 lb) and 1.36 m (4.5 ft), may be the smallest adult cetacean on record.[9] Its appearance resembles that of a porpoise, but its conspicuous behaviour is typical of a dolphin. The dorsal fin has a long, straight leading edge which ends in a curved tip. The trailing edge is typically concave, but not falcate. The fluke has a notch in the middle.
Sexes are easily distinguished by the different shape of the black blotch on the belly — it is shaped like a teardrop in males but is more rounded in females. Females reach breeding age at six to 9 years. Males reach sexual maturity at about the same age. Mating occurs in the spring and summer and calving occurs after a gestation period of 11 months during the spring and summer.[6][10] The Commerson's dolphin has been known to live up to eighteen years in the wild, while in captivity the oldest individual was at least 33 years old at the time of death.[11]
Dolphins of the kerguelenensis subspecies tend to be larger than those of C.c.commersonii, and differ in patterning in that they are dark grey instead of black, and light grey instead of white, except ventrally. The demarcation between areas of the pattern is also less clearly demarcated.[12]
Commerson's dolphin is very active. It is often seen swimming rapidly on the surface and leaping from the water. It also spins and twists as it swims and may surf on breaking waves when very close to the shore. It will bow-ride and swim behind fast-moving boats. It is also known to swim upside-down, which is thought to improve the visibility of its prey.
This dolphin feeds on a mix of coastal and pelagic fish and squid. Those in the South American subpopulation supplement their diets with crustaceans.[13][14][15] Individuals have been recorded as entering the Santa Cruz River to forage there during low tide.[16]
They can be found in estuaries, especially during the breeding season.[6][16]
The IUCN lists Commerson's dolphin as Least Concern in its Red List of Threatened Species. The proximity of the dolphin to the shore makes accidental killing in gillnets a common occurrence. The dolphin was killed for use as crab bait by some Argentinian and Chilean fishermen in the 1970s and 1980s, but this practice has since been curtailed.[2]
The Commerson's dolphin population of South America is listed on Appendix II[17] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II[17] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.[18]
These dolphins have been known to be displayed in a few aquariums.[19][20]
Commerson's dolphin (Cephalorhynchus commersonii), also referred to by the common names jacobita, skunk dolphin, piebald dolphin, panda dolphin, or tonina overa (in South America), is a small oceanic dolphin of the genus Cephalorhynchus. Commerson's dolphin has two geographically-isolated but locally-common subspecies. The principal subspecies, C.c.commersonii, has sharply-delineated black-and-white patterning and is found around the tip of South America. The secondary subspecies, C.c.kerguelenensis, is larger than C.c.commersonii, has a less-sharply delineated dark and light grey patterning with a white ventral band, and is found around the Kerguelen Islands in the Indian Ocean.
The dolphin is named after French naturalist Dr Philibert Commerson, who first described them in 1767 after sighting them in the Strait of Magellan.
