Species

Peale's dolphin

February 22, 2011, 4:39 am
Content Cover Image

Peale's dolphin Falkland Islands postage stamp. Source: Encyclopedia of Life

Peale's dolphin is a marine mammal from the Porpoise family within the order of Cetaceans. The biology of Peale's dolphin is not well known, as it seldom strands, and so few specimens have been examined, and the species has not been kept in captivity. Most feeding appears to occur in kelp beds, where small groups of around five to thirty individuals are thought to hunt squid, octopus, and sometimes shrimp. Larger groups have also been observed, and may hunt cooperatively in more open water, herding larger shoals of fish. 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. Peale's porpoise is another alternate name of this species.

caption Peale's Dolphin, Near Ventisquero Pio XI, Feb 2006, Source: Frank Holden
caption Size comparison of an average human and a Peale's dolphin (Lagenorhynchus australis). Source: Chris Huh
Conservation Status
Data Deficient

Scientific Classification

Kingdom: Anamalia (Animals)
Phylum:--- Chordata
Class:------ Mammalia (Mammals)
Order:-------- Cetacea (Cetaceans)
Family:-------- Delphinidae (Porpoise)
Genus:----------Lagenorhynchus
Species:----------- Lagenorhynchus australis (Peale, 1848)

Little information is available on reproduction in this species, but calves have been reported from spring to autumn (October to April). 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. 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.

Physical description

Lagenorhynchus 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 Peale's dolphin tend to look the same as the adults, but are much lighter in colour. They become darker as they mature. 

The teeth of Lagenorhynchus australis appear 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 centimetres (cm), and the dorsal fin can be up to 50 cm in height. The tail fluke is generally 30 to 60 cm wide, and the beak is up to five cm in length. These animals may weigh up to 115 kg. (de Haro and Iniquez, 1997; Goodall et al., 1997a; MacDonald, 1984; Nowak, 1999) 

Reproduction

In general it has been noted that species within the genus Lagenorynchus have gestation periods of ten to twelve months. Calving season for Lagenorhynchus 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 two years. It is not known whne these animals mature sexually. (Goodall et al., 1997a; Goodall et al., 1997b; Nowak, 1999)

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 six months. It is not known what role males play, if any, in the parental care of this species. (Nowak, 1999) 

Lifespan

Scientists are able to determine the age of Peale's dolphins by examining at their teeth, but no published studies explain the associated proocols. The oldest recorded specimen of Lagenorhynchus australis was thirteen years old.(Goodall et al., 1997a; Goodall et al., 1997b) 

Behavior

caption Coastal waters of Chilean Tierra del Fuego habitat of Peale's dolphin.
@ C.Michael Hogan
Lagenorhynchus australis display many different types of behavior. When swimming, the Peale's dolphin is known for jumping, humping, spinning and tailslapping. Some tail slaps are believed to aid in foraging by directing fish towards other dolphins.

These animals tend to be gregarious and swim in small groups from one to 13 individuals. Most sightings are of groups with 2 to 4 members. In the summer months the average group size is two members. Some groups as large as 100 members have been recoreded. When such large aggregations occur, the dolphins tend to divide themselves up into sub-groups. Larger groups tend to be sighted more often in the months of January and February.

When swimming Lagenorhynchus australis will surface about three to four times per minute and dive between one and 130 seconds. The average dive endures less than 60 seconds. The young have been seen surfacing a few more times a minute than the adults. When coming up from a dive, they expose only the blowhole and a part of the dorsal fin. Groups tend to surface together as if in some type of rhythmic pattern.

When swimming rapidly Peale's dolphins display a behaviour where water splashes up high around their faces, and they have accordingly been nicknamed plowshare dolphins. When floating these animals tend to lie on their sides so they can look up at surface objects such as boats around them. Lagenorhynchus australis is very social around all kinds of boats and are often seen playing or swimming around them.

Peale's individuals often follow in the wake of a boat, but once the propeller is turned off, the dolphin's interest seems to subside. Many of these interactions are for playful purposes but some are for the sole purpose to help them catch their food. (de Haro and Iniquez, 1997; Goodall et al., 1997a; Goodall et al., 1997b; Nowak, 1999; Schiavini et al., 1997)

Sounds emitted under water by Lagenorhynchus 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. (Goodall et al., 1997a; Goodall et al., 1997b) 

Distribution

Lagenorynchus australis is chiefly found to occur in the mildly cold and temperate waters off of South America and the Falkland Islands in the South Atlantic Ocean. A single sighting has been reported near the Cook Islands also. (Nowak, 1999; Reeder and Wilson, 1993) 

Habitat

Lagenorhynchus australis is usually found in coastal waters. 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 the Peale's dolphin 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 Lagenorhynchus australis.

Ecosystem roles

Lagenorhynchus australis has been known to interact with many species of ocean life including the following:

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.(Goodall et al., 1997a; Goodall et al., 1997b) 

Feeding habits

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, Lagenorhynchus 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.

Few Lagenorhynchus australis have been dissected for examining the stomach contents, but known prey species are extensive. Species consumed include: Pleoticus muelleri (Argentine shrimp), squid (Loligo gahiand 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). 

Conservation status

IUCN: Data Deficient 

Threats

There are no known predators of Lagenorhynchus australis

Lagenorynchus australis has not been studied sufficiently to determine population trends. There are certain human sources of this species mortality that are a continuing concern. These include shore-set gill nets (accidental catch), inshore fishing (incidental catch), and salmon farms near Chile. (Some have been entrained in the anti-pinniped nets despite the loud sounds made underwater to deter them). Deep sea fishermen have been known to occasionally take Peale's 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 Lagenorhynchus australis as bait.

References and further reading

  • Encyclopedia of Life. 2020. Lagenorhynchus australis
  • IUCN Red List (May, 2009)
  • Jefferson, T.A., Webber, M.A. and Pitman, R.L. (2008) Marine Mammals of the World: A Comprehensive Guide to their Identification. Academic Press, London.
  • CITES (May, 2009)
  • Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (2002) Encyclopedia of Marine Mammals. Academic Press, San Diego, California. Search! 5. Macdonald, D.W. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
  • Martin, A.R. (1990) Whales and Dolphins. Salamander Books, London.
  • Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciari, G. (2003) Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans. IUCN/SSC Cetacean Specialist Group, IUCN, Gland.
  • Viddi, F.A. and Lescrauwaet, A.K. (2005) Insights on habitat selection and behavioural patterns of Peale's dolphins (Lagenorhynchus australis) in the Strait of Magellan, Southern Chile. Aquatic Mammals, 31 (2): 176 - 183.
  • Iñíguez, M.A. and de Haro, J.C. (1994) Preliminary report on the feeding habits of the Peale's dolphin (Lagenorhynchus australis) in southern Argentina. Aquatic Mammals, 21 (1): 35 - 37.
  • Nowak, R.M. (1991) Walker's Mammals of the World. The Johns Hopkins University Press, Baltimore and London
  • Convention on Migratory Species: Lagenorhynchus australis (May, 2009)
  • Convention on Migratory Species (May, 2009)
  • Claver, J., M. Iniguez, D. Lombardo, I. von Lawzewitsch. 1992. Preliminary Observations on Ovarian Activity and Sexual Maturity in Female Peale's Dolphin (Lagenorynchus australis). Aquatic Mammals, 18: 85-88
  • Goodall, R., J. de Haro, F. Fraga, M. Iniquez, K. Norris. 1997. Sightings and Behavior of Peale's Dolphins, Lagenorynchus australis, with Notes on Dusky Dolphins, L. obscurus, off Southern Most South America. International Whaling Commission Report, 47: 757-775
  • Goodall, R., K. Norris, W. Schevill, F. Fraga, R. Praderi. 1997. Review and Update on the Biology of the Peale's Dolphin, Lagenorynchus australis. International Whaling Commission Report, 47: 777-796.
  • IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
  • Lescrauwaet, A. 1997. Notes on the Behavior and the Ecology of the Peale's Dolphin, Lagenorynchus in the Strait of Magellan, Chile. International Whaling Commission Report, 47: 747-755.
  • MacDonald, D. 1984. Encyclopedia of Mammals. N.Y.: Facts on File Publications.
  • Mead, James G., and Robert L. Brownell, Jr. / Wilson, Don E., and DeeAnn M. Reeder, eds. 2005. Order Cetacea. Mammal Species of the World: A Taxonomic and Geographic Reference, 3rd ed., vol. 1. 723-743 Search! Nowak, R. 1999. Walkers Mammals of the World, Sixth ediition. Baltimore and London: Johns Hopkins University Press
  • Perrin, W. (2010). Lagenorhynchus australis (Peale, 1848). In: Perrin, W.F. World Cetacea Database. Accessed through: Perrin, W.F. World Cetacea Database at http://www.marinespecies.org/cetacea/aphia.php?p=taxdetails&id=254980 on 2011-02-05
  • Reeder, D., D. Wilson. 1993. Mammal Species of the World ed. 2. Washington and London: Smithsonian Institution Press.
  • Rice, Dale W. 1998. Marine Mammals of the World: Systematics and Distribution. Special Publications of the Society for Marine Mammals, no. 4. ix + 231
  • Schiavini, A., R. Goodall, A. Lescrauwaet, M. Koen Alonso. 1997. Food Habits of the Peale's Dolphin, Lagenorynchus australis; Review and New Information. International Whaling Commission Report, 47: 827-834.
  • UNESCO-IOC Register of Marine Organisms Search! Wilson, Don E., and DeeAnn M. Reeder, eds. 1993. Mammal Species of the World: A Taxonomic and Geographic Reference, 2nd ed., 3rd printing. xviii + 1207
  • Wilson, Don E., and F. Russell Cole. 2000. Common Names of Mammals of the World. xiv + 204
  • de Haro, J., M. Iniquez. 1997. Ecology and Behavior of the Peale's Dolphin, Lagenorynchus australis (Peale, 1848), at Cabo Virgenes (52 degrees 30' S., 68 degees 28'W), in Patagonia, Argentina. International Whaling Commission Report, 47: 723-727.

 

Glossary

Citation

Life, E. (2011). Peale's dolphin. Retrieved from http://www.eoearth.org/view/article/155163

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