Cephalorhynchus commersonii (Lacépède, 1804)

Common Names and Taxonomy

Commerson's dolphin (scientific name Cephalorhynchus commersonii) has several other common names: jacobita, skunk dolphin, piebald dolphin, panda dolphin, and tonina overa, the name it is called in South America. It is a small oceanic dolphin that belongs to the genus Cephalorhynchus.

Subspecies Overview

This species has two geographically isolated, but locally common, subspecies. The primary nominate subspecies, C. c. commersonii, has sharply defined black-and-white body patterning, and lives around the southern tip of South America.

Second Subspecies Traits

The second subspecies, C. c. kerguelenensis, is larger than the nominate subspecies, has less sharply defined dark and light grey patterning with a white band on its ventral side, and is found around the Kerguelen Islands in the Indian Ocean.

Etymology

The species is named for French naturalist Dr. Philibert Commerson, who first described the animals in 1767 after sighting them in the Strait of Magellan.

Subspecies Distribution Gap

The two disjunct subspecies occupy geographically separate regions, separated by 130° of longitude and approximately 8,500 km (5,300 mi). The reason for this separated distribution is currently unknown.

Global Population Status

The total global population of Commerson's dolphin has not been calculated, but the species is confirmed to be locally common in its ranges.

Nominate Subspecies Range

The main subspecies, C. c. commersonii, lives in inshore waters of multiple inlets in Argentina including Puerto Deseado, throughout the Strait of Magellan, around Tierra del Fuego, and near the Falkland Islands (Las Malvinas).

Strait of Magellan Population Estimate

A 1984 survey estimated a population of 3,200 individuals living in the Strait of Magellan.

Kerguelen Subspecies Discovery

The second subspecies, C. c. kerguelenensis, was first discovered in the 1950s.

Kerguelen Subspecies Habitat

It lives near the Kerguelen Islands in the southern Indian Ocean, and prefers shallow water habitats.

South Africa Sighting

In 2004, a single wandering Commerson's dolphin of unconfirmed origin was sighted on South Africa's Agulhas Bank.

Sighting Distance Details

This sighting location is 4,200 km (2,600 mi) from the Kerguelen Islands and 6,300 km (3,900 mi) from South America.

Sighting Context

While the Kerguelen Islands are closer to the sighting site, reaching Agulhas Bank from there would require swimming against the Antarctic Circumpolar Current.