Blackchin Dolphin

The biology of Peale's dolphin is not well known, as it seldom strands, few specimens have been examined, and the species has not been kept in captivity (2) (4) (6). Most feeding appears to occur in kelp beds (4) (8), where small groups of around 5 to 30 individuals are thought to hunt squid, octopus, and sometimes shrimps (2) (4) (6) (9). Larger groups have also been observed (2) (4), and may hunt cooperatively in more open water, 'herding' larger shoals of fish (4) (8). Peale's dolphin is often seen associating with other dolphin species, particularly Commerson's dolphin (Cephalorhynchus commersonii), and frequently bow-rides, producing loud splashes and slaps when leaping and swimming at the surface (2) (4) (6). Little information is available on reproduction in this species, but calves have been reported from spring to autumn (October to April) (2) (4). In general, Lagenorhynchus species give birth to a single young after a gestation period of around 10 to 12 months, with the young measuring around one metre at birth (2) (10). Migration in Peale's dolphin is not well understood, but individuals around southern Tierra del Fuego appear to move inshore in the summer, possibly following fish migrations (4) (11).

More information is needed on the extent of the exploitation of Peale's dolphin for crab bait (4) (7). The Chilean government has undertaken some measures to help regulate the use of marine mammals in crab fisheries, including educating fishing communities and providing alternative sources of bait, and the practice of using dolphins as bait is reported to have declined in recent years. However, a certain amount of illegal fishing and baiting may continue (7). Other recommended conservation actions for Peale's dolphin include further research into its biology and abundance, identification and protection of key habitats, education campaigns, and enforcement of hunting regulations (1) (11). In addition to its listing on Appendix II of the Convention on International Trade in Endangered Species (CITES) (3), meaning international trade in Peale's dolphin should be carefully controlled, the species is also listed on Appendix II of the Convention on Migratory Species (CMS) (12), based on the fact that its movement through the Beagle Channel and Strait of Magellan is likely to involve the national boundaries of Argentina and Chile (11).

A fairly robust dolphin with a short, rounded snout, Peale's dolphin is greyish black above and mostly white below. A curved, light grey flank patch runs from behind the dorsal fin to the tail, while a second light grey patch on the chest runs from the eye to the middle of the body. This second patch is separated from the white belly by a well-defined black line, which loops above a small white patch in the 'armpit', under the flipper (2) (4) (5) (6). The flippers and dorsal fin are dark, and the dorsal fin is sickle-shaped, with a light grey trailing edge. The face, snout, melon and most of the chin are dark grey-black, which, together with the black line below the chest patch, readily distinguishes Peale's dolphin from similar species such as the dusky dolphin (Lagenorhynchus obscurus). (2) (4) (6). Young Peale's dolphins are lighter grey than adults, with less clear definition between the chest and flank patches (2) (4).

Peale's dolphin occurs in open coastal waters over shallow continental shelves, as well as in bays, inlets, channels, around islands and in the openings to fjords (1) (2) (4). Although recorded at depths of up to 300 metres, the species prefers shallower coastal waters (1) (2), and appears to be particularly associated with kelp beds (2) (4) (8).

Peale's dolphin has a somewhat restricted range, being found only around the southern tip of South America, as far north as northern Argentina and Santiago, Chile. The species is commonly seen around the Falkland Islands and over Burdwood Bank, south of the Falkland Islands (2) (4) (6) (7). Possible sightings of Peale's dolphins have also been reported from tropical waters, at Palmerston Atoll in the South Pacific, but this is considered to be outside the normal range and may even represent a new, undescribed species (2) (4) (6).

Classified as Data Deficient (DD) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Although reported to be relatively common within its range, no population estimates are available for Peale's dolphin (1) (2) (7). There is also a lack of information on the impacts of the threats to the species, making it difficult to assess its conservation status (1). Peale's dolphin has been heavily exploited since the 1970s for use as crab bait, a practice which is thought to have reduced the species' abundance by the late 1980s (1) (2) (7). Although now banned, the practice still occurs in Chile, although at lower levels than before (1) (4) (7). There is concern that the number of Peale's dolphins taken could lead to problems for the species, especially given its restricted distribution (6). Peale's dolphin is also occasionally entangled and drowned in gillnets, and sometimes caught in anti-predator nets around salmon pens in Chile, although this is thought to occur only at low levels (1) (2) (4) (7). Other potential threats to Peale's dolphin include organochlorine pollution (11), and any threats to the kelp forests on which the species depends (8). Tour operators have also recently begun offering trips to see Peale's dolphins near Punta Arenas in Chile, but no laws exist to regulate this activity or to monitor its potential impacts (7).