Long-beaked common dolphin (Delphinus capensis)

Description

Long-beaked common dolphin fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Long-beaked common dolphin description

Since the mid-1990s, the common dolphin has been split into two species, the long-beaked common dolphin and the short-beaked common dolphin ^{(2) (4)}. As implied by their respective names, beak length is important for distinguishing between the two species, but is not the only defining feature ⁽²⁾. Based on specimens from California, both species have a bold, light and dark hour-glass pattern on the side of the body, forming a V below the dorsal fin, but the colouration of the long-beaked species is noticeably muted. A slightly curved dorsal fin is equally characteristic of both species but the body of the long-beaked common dolphin is more slender and the head is less rounded ^{(2) (5)}. The long-beaked dolphin has more teeth than any other dolphin with 47 to 67 pairs lining each jaw ⁽⁶⁾.

Although an exceptionally long-beaked form occurring in parts of the Indo-Pacific is sometimes considered to be a separate species, the most recent evidence indicates that it is a subspecies of the long-beaked common dolphin, Delphinus capensis tropicalis ^{(1) (4) (7)}.

There is growing evidence that several scattered populations, currently labelled as long-beaked common dolphins, may have actually evolved independently of each other in response to similar ecological conditions. The implications of this convergent theory are that these populations potentially represent different subspecies of the short-beaked common dolphin, or even unique species. Supporters of this alternative taxonomic view point to the fact that, in parts of the long-beaked common dolphin’s described range, it is very difficult to separate the two species of common dolphin on either morphological or genetic grounds ⁽⁸⁾. Needless to say, more research is needed before the true taxonomic status of this species will be revealed ⁽⁹⁾.

French

Dauphin Commun A Bec Large.

Spanish

Delfín Común A Pico Largo.

Size

Male length: 2 - 2.6 m ⁽²⁾

Female length: 1.9 - 2.3 m ⁽²⁾

Long-beaked common dolphin biology

Besides what is known about common dolphins in general, little is yet known about the specific behaviour of the long-beaked dolphin ⁽²⁾. Common dolphins are amongst the most gregarious mammals and are sometimes seen in groups of more than 1,000 individuals ^{(4) (6)}. These large schools may comprise smaller social units of 10 to 30 closely related dolphins ⁽⁵⁾. At the surface, common dolphins are extremely energetic, moving in and out of the water in a series of high speed jumps, known as porpoising, or leaping vertically to create a dramatic splash on landing ^{(5) (6)}. Speeds in excess of 40 kilometres per hour can be reached and these dolphins will often ride the bow waves of ships ^{(4) (5)}.

Common dolphins typically dive for two to three minutes in the pursuit of food and can reach depths of up to 280 metres ⁽⁴⁾. A large geographic range accounts for a diverse mix of prey, that includes various species of small schooling fish and squid ^{(4) (5) (6)}.

Breeding usually takes place between spring and summer, with a sexually mature female giving birth every two or three years. The calf is born following a gestation period of nine to eleven months and is weaned after around six months. The age at which sexual maturity is reached appears to vary with region such that males may take two to seven years and females may take between three and twelve years. The maximum life expectancy is estimated to be around 22 years ^{(4) (5)}.

Long-beaked common dolphin range

As the long-beaked common dolphin was only given distinct species status in 1994, its exact distribution in the three major oceans is yet to be fully identified ^{(1) (5)}. The nominate subspecies, D. c. capensis is known from disjunctive populations on the east and west coast of South America, southern Mexico, central California, West Africa, South Africa, southern Japan, Korea, northern Taiwan and possibly China ⁽¹⁾. The less widespread subspecies, D. c. tropicalis, is known only from the northern Indian Ocean and Southeast Asia ⁽⁵⁾.

Long-beaked common dolphin habitat

The long beaked common dolphin is generally found within 180 km of the coast in warm temperate and tropical waters. It rarely occurs near islands that are far from mainland coasts ^{(1) (5)}.

Long-beaked common dolphin status

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

Long-beaked common dolphin threats

Despite having a smaller distribution than the short-beaked dolphin and probably a far smaller overall population, the long-beaked dolphin is thought to still have a relatively widespread population in the high tens of thousands or even low hundreds of thousands ^{(1) (7)}. However, in some regions, such as West Africa, East Asia and the east and west coasts of South America, undetermined numbers of long-beaked dolphin are being directly exploited, or taken as incidental bycatch in other fisheries ⁽¹⁾. In Peru and West Africa in particular, there is increasing concern about the number of long-beaked dolphin being caught and used for human food and shark-bait ^{(1) (6) (7)}. Given the lack of data quantifying these impacts, the long-beaked dolphin is currently listed as Data Deficient on the IUCN Red List ⁽¹⁾.

Long-beaked common dolphin conservation

The long-beaked common dolphin benefits from The Pacific Offshore Cetacean Reduction Plan which was implemented in 1997 to reduce the number of cetaceans killed or injured incidentally in driftnets. Amongst other obligations, the plan requires that vessels use ‘pingers’ which send out an acoustic pulse to deter marine mammals such as the long-beaked common dolphin ⁽⁶⁾.

In West Africa, WWF are working to develop an action plan for the conservation of small cetaceans in the region. This plan is to be built around formulating and implementing protective policies and laws, and improving scientific knowledge and public awareness ⁽¹⁰⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For further information on the conservation of cetaceans see: 

• Whale and Dolphin Conservation Society:
  www.wdcs.org
• American Cetacean Society:
  www.acsonline.org
• Sea Shepherd Conservation Society:
  www.seashepherd.org

Authentication

Authenticated (24/02/09) by William F. Perrin, Senior Scientist for Marine Mammals, National Marine Fisheries Service, Southwest Fisheries Science Center.

http://swfsc.noaa.gov

Glossary

Bycatch

In the fishing industry, the part of the catch made up of non-target species.

Cetaceans

A group comprising all whale species; therefore including dolphins and porpoises. Now considered to be part of the Order Cetartiodactyla, with the even-toed ungulates (e.g., cattle, pigs, antelopes, sheep, goats, hippos, giraffes, camels). The closest living relatives of the cetaceans genetically are the hippos.

Dorsal fin

The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.

Gestation

The state of being pregnant; the period from conception to birth.

Morphological

Referring to the visible or measurable characteristics of an organism.

Nominate subspecies

The subspecies indicated by the repetition of the specific name. Thus, in this case the Delphinus capensis capensis is the nominate subspecies of the long-beaked common dolphin, Delphinus capensis.

Taxonomic

Refers to taxonomy, the science of classifying organisms, grouping together animals which share common features and are thought to have a common ancestor.

References

1. IUCN Red List (December, 2008)
   http://www.iucnredlist.org/
2. Carwardine, M., Hoyt, E., Fordyce, R.E. and Gill, P. (1998) Whales and Dolphins. HarperCollins Publishers, London.
3. CITES (September, 2008)
   http://www.cites.org
4. Nowak, R.M. (1999) Walker's Mammals of the World. Johns Hopkins University Press, Baltimore, Maryland.
5. Perrin, W.F. (2008) Common dolphins. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (Eds) Encyclopedia of marine mammals. Second Edition. Academic press, Amsterdam.
6. NOAA Fisheries Service (December, 2008)
   http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/commondolphin_longbeaked.htm
7. Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciara, G. (2003) Dolphins, Whales and Porpoises: 2002–2010 Conservation Action Plan for the World's Cetaceans. IUCN/SSC Cetacean Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK.
8. Natoli, A., Cañadas, A., Peddemors, V.M., Aguilar, A., Vaquero, C., Fernández- Piqueras, P. and Hoelzel, A.R. (2006) Phylogeography and alpha taxonomy of the common dolphin (Delphinus sp.). Journal of Evolutionary Biology, 19: 953 - 954.
9. Perrin, W.F. (2009) Pers. comm.
10. WWF (December, 2008)
    http://www.panda.org/about_wwf/where_we_work/africa/where/cape_verde/index.cfm?uProjectID=9F0781