Blackchin Dolphin

There are no known predators of L. australis.

L. australis has many distinguishing physical characteristics. Some of these include a torpedo shaped body, a dark gray back, a white belly, a light gray area on flanks that extends from behind to the anus and a skinny white band that begins behind the dorsal fin and gets wider as it extends backwards. This latter feature is termed the “tail stock”.

L. australis has double black rings around both eyes and that extend forward to the nose. A final distinguishing feature that separates this species from other similar looking species is a circular patch of varying gray colors that is right on the thoracic area of the back.

The young of L. australis tend to look the same as the adults, but are much lighter in color. They become darker as they mature.

The teeth of L. australis seem to be variable. The maximum number on each upper jaw is thirty-seven and thirty-six on each lower jaw. Many teeth are hidden in the gums of the mouth.

The pectoral fin length is approximately 30 cm, and the dorsal fin can be up to 50 cm in height. The tail fluke is generally 30-60 cm wide, and the beak is up to 5 cm in length.

These animals may weigh up to 115 kg.

Average mass: 115 kg.

Range length: 150 to 310 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Scientists are able to determine the age of Peale's dolphins by looking at their teeth but no records or studies explain how this is accomplished. The oldest recorded specimen of L. australis was thirteen years old.

Range lifespan
Status: wild: 13 (high) years.

L. australis is usually found near the coast. These dolphins love to swim in and around the channels within kelp beds. They have also been sighted around sandbars and shallow bays. Most sightings of L. australis occur while there are strong tidal currents and during medium tides.

Peale's dolphins tend to inhabit two types of coastline. In the south they are usually found near channels and fjords. In the northern and eastern coast ranges, where the continental shelf underwater is very wide, they tend to be found in the open coast. In the open coast they have been found to swim as deep as 300 meters. There is little kelp there, but more southward and towards the Falkland Islands there are many kelp beds and this is where you will mostly find L. australis.

Range depth: 300 (high) m.

Habitat Regions: temperate ; saltwater or marine

Aquatic Biomes: coastal

There are many other common names for this species beside the common name Peales dolphin. These are Peales Porpoise, black-chinned dolphin, and Southern white-sided dolphin. In Spanish it used to be called llampa or tunina in Chile. Now it is called delfin austral (southern dolphin) in Chile and Argentina.

(Goodall et al, 1997)

Sounds emitted under water by L. australis include low frequency clicking noises and a "rapid tonal sound", but no whistling. There is little research on vocalizations, as they seem to be very timid communicators around boats taking the data.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic ; chemical

Lagenorynchus australis has not been studied intensively to determine population trends. There are a few human sources of mortality that may be of a concern in the future. These include shore-set gill nets (accidental catch), inshore fishing (incidental catch), and salmon farms near Chile (a few have been caught in the anti-pinniped nets despite the loud sounds made underwater to deter them). Deep sea fishermen have been known to occasionally catch a few Peales dophins in their mid-water nets. A more serious situation is occurring near crab fisheries where the use of nets has been outlawed. Fisheries have been known to use harpooned L. australis as bait. (Nowark, 1999 and Goodall et al, 1997)

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: data deficient

Very little has been recorded about the developmental cycle in L. australis. The only studies recorded represent measurements of the ovaries of a few female L. australis. These measurements were representative of the different sexual maturities and the data showed the older females as having more ovarian scars. Even less information has been gathered about males and their sperm activity. There was not enough conclusive information to make any statements. No information has been collected about the young in L. australis and there have been no specimens collected or found with a fetus inside. Because of this we are left to assume that this species is similar in the developmental patterns of better-known dolphin species.

(Goodall et al, 1997 and Claver et al, 1992)

It is difficult to speculate on how these acquatic mammals might negatively impact humans. There are no reports of negative interactions, but it is possible that through their predatory behavior, populations of Peale's dolphins could negatively impact commercial or subsistence fisheries. However, this is just speculation, and there are no reports of this being the case.

Humans have occasionally harpoon Peales dolphins for use as bait.

There is so little known about Peales dolphins that their effect on the pelagic ecosystem is unknown. However, because they prey upon a number of types of animals, there is a potential impact of these dolphins upon prey populations.

Species Used as Host:

• Anisakis simplex

Peale's dolphins may feed in groups or alone. It has been hypothesized that this species may tend to feed alone when food is scarce and in groups when food is of abundance. When in groups, L. australis usually exhibits what is called "flower" or "starburst" feeding. They encircle their prey until they form a large group and then they feast. This is mostly done within the kelp beds. When they are sighted eating alone it is usually close to shore. When diving for prey it has been reported that they stay under water from between 10.36 seconds to 1.46 minutes.

Not very many L. australis have been dissected for examining the stomach contents, but known prey species are very extensive all the same.

Foods eaten include: Pleoticus muelleri (Argentine shrimp), squid (Loligo gahi and Illex argentinus), Kingklip fish (Genypterus blacodes), Argentine hake (Merluccius hubbsi), southern cod (Salilota australis), hagfish (Myxine australis), Pantagonian grenadier (Marcuronus magellanicus), red octopus (Enteroctopus megalocyathus), other species of herring, makarel, capelin, anchovies, crustaceans and whelks (gastropods).

Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans

Primary Diet: carnivore (Piscivore , Molluscivore )

Lagenorynchus australis lives mostly in the mildly cold and temperate waters off of South America and the Falkland Islands in the South Atlantic Ocean. One sighting has been reported near the Cook Islands also.

Biogeographic Regions: neotropical (Native ); atlantic ocean (Native )

Little is known bout the mating system of these animals.

In general it has been noted that species within the genus Lagenorynchus have gestation periods of ten to twelve months. Calving season for L. australis usually occurs between the southern spring and autumn but a calf can be born as early as October. Females tend to have only one calf per birth (maybe two) and they also move more inshore to do this. Some records show that when two of these dolphins were spotted together in the past, they were only considered a mother and calf if the smaller of the two animals was one third or less the size of the adult accompanying it. On visual sightings alone, this is probably still the most common way to tell a calf from an adult.

Although data are not available for this species, in another member of the genus, L. acutus, young are between 90 and 125 cm at birth. They nurse for about 18 months, and become independent of their mothers around the age of 2 years. It is not known whne these animals mature sexually.

Breeding season: It is not known for certain when mating occurs, but births occur during the Southern Spring to Autumn.

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 10 to 12 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

Young are precocial and swim along side of their mothers from birth. The mother provides her calf with milk for approximately 18 months, although the calf may remain dependent upon her for an additional 6 months. It is not known what role males play, if any, in the parental care of this species.

Parental Investment: precocial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence; extended period of juvenile learning

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).

The general body shape of Peale's dolphin is typical for dolphins of the genus Lagenorhynchus. Few specimens have been examined, but observations of Peale's dolphins suggest they are the most robust of the Southern Hemisphere dolphins of this genus. The dorsal fin is pointed and falcate. Peale's dolphins share coloration pattern components with both dusky and Pacific white-sided dolphins. Peale's dolphins are greyish black above and white below. They have a curved flank patch of light grey with a single dorsal spinal blaze, or "suspender", fading into the black of the back near the blowhole. A large pale grey thoracic patch extends from the eye to midbody; it is separated from the white below by a well-developed dark stripe. The stripe loops up above a small white patch under the flipper. The flippers are grey-black, and the dorsal fin is dark grey-black, with a thin crescent of light grey on the trailing margin. Most of the beak is dark grey to black. Tooth counts for 3 specimens ranged from 27 to 33 on each side of each jaw. Can be confused with: Peale's dolphins are most easily confused with dusky dolphins. The face, rostrum, melon,and most of the chin of Peale's dolphins are dark grey-black, as if encased in a mask. This feature, plus the well-developed black stripe below the thoracic patch, readily distinguishes Peale's dolphins from dusky dolphins.

The largest specimen recorded was 2.16 m long, and adults are estimated to weigh about 115 kg. Length at birth is estimated to be about 1 m.

Peale's dolphins have been seen in small groups (5 to 30 are typical). Photoidentification studies have shown that some dolphins spend the entire year in limited areas close to shore, in the magellan strait. They frequently bowride, and will sprint to a ship's bow. At the bow, they often speed ahead, leap high into the air and fall back into the water on their sides, producing a large splash with a loud slapping noise. Newborns have been observed in Magellan Strait as early as October. Little is know of food and feeding habits; one animal collected in the Falkland Islands had recently consumed an octopus and others have been observed feeding on róbalo (snooks, family Centropomidae) and pejerrey (silversides, family Atherinidae).

Peale's dolphins are incidentally entangled and drowned in nets; also, they are intentionally harpooned in the Strait of Magellan and around Tierra del Fuego. The number harpooned, for use as bait in crab traps, may pose a serious threat to their status. A population estimate does not exist. IUCN: Insufficiently known.

Peale's dolphin (Lagenorhynchus australis) is a small dolphin found in the waters around Tierra del Fuego at the foot of South America. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, since Rice's work Peale's dolphin has been adopted as the standard common name.