MarLIN

information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Bottle-nosed dolphin (Tursiops truncatus)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.

Summary

Description

Tursiops truncatus is a large dolphin up to 4 m long, with a dark to light grey back that fades to white on its underside and a dark stripe from eye to flipper. It has a pronounced snout and the lower jaw protrudes in front of the upper. The dorsal fin is tall and backward-curving from the middle of the back. There are between 18 - 26 pairs of large teeth in each jaw. Dolphins regularly surface to breathe, the maximum time spent under water being about 7 minutes.

Recorded distribution in Britain and Ireland

Resident populations are known from Cardigan Bay in west Wales, the Moray Firth in east Scotland and the west coast of Ireland. Also recorded off the south and southwest coasts of England, the western Isles of Scotland and in the Irish Sea.

Global distribution

Occurs worldwide, primarily in coastal and inshore regions of tropical and temperate waters and occasionally in offshore waters such as the eastern Pacific. Generally not found outside latitude 45 degrees except around Britain and northern Europe.

Habitat

Tursiops truncatus is commonly found in coastal waters and along main shipping routes. The population density appears to be higher inshore and dolphins may be found from deep coastal waters into the shallow water off river entrances, but not in fresh water.

Depth range

-

Identifying features

  • Light to dark grey above with paler underbelly.
  • Up to about 4 m long.
  • Torpedo shaped body with tall, backward curving dorsal fin.
  • The short stubby beak is distinct from the curving head.

Additional information

There is considerable variation in size and colour between populations of Tursiops truncatus worldwide. The European bottle-nosed dolphin tends to be larger and browner than those in the west Altlantic. Group size is commonly less than 20, but groups of over 1000 have been recorded offshore. For information on how to report dolphin sightings see 'Sealife Signpost'.

Tursiops truncatus is listed in the UK Biodiversity Action Plan list of species of conservation concern (Biodiversity Steering Group, 1995). All species of cetaceans are given protection under the Wildlife and Countryside Act 1981 and the Wildlife (Northern Ireland) Order 1985. All cetacean species are listed on Annex A of EU Council Regulation 338/97 and therefore treated by the EU as if they are on CITES Appendix I thus prohibiting their commercial trade. The bottle-nosed dolphin is listed in Annex II and IV (Animal and Plant Species of Community Interest in Need of Strict Protection) of the EC Habitats Directive. Under Annex IV the keeping, sale or exchange of the species is banned, as well as deliberate capture, killing or disturbance. The Directive requires that member states monitor the incidental capture and killing of all dolphins. Marine Special Areas of Conservation (SACs) for bottle-nosed dolphins are being established in the Moray Firth in north-east Scotland, and in Cardigan Bay in west Wales. An 'Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas' (ASCOBANS), formulated in 1992, has now been signed by seven European countries, including the UK. The Agreement makes provision for protection of specific areas, monitoring, research, information exchange, pollution control and heightening public awareness. The North and Baltic Sea populations of the bottle-nosed dolphin are included on Appendix II of the Bonn Convention. (Anon, 1999e).

A report on dolphins in the south west of England (Marine Connection & Wildlife Trusts, 2007) reveals a significant decline in the number of sightings of the bottle-nosed dolphin since 2000.

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Further information sources

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Bibliography

  1. Anonymous, 1999e. Small dolphins. Grouped Species Action Plan. http://www.ukbap.org.uk/UKPlans.aspx?ID=337, 2002-01-25

  2. Biodiversity Steering Group, 1995. Biodiversity: the UK Steering Group report, vol. 1 & 2. London: HMSO.

  3. Bruyns, W.F.J.M., 1971. Field guide of whales and dolphins. Amsterdam: Publishing Company Tors.

  4. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  5. Jefferson, T.A., Leatherwood, S. & Webber, M.A., 1994. FAO species identification guide. Marine mammals of the world. Rome: United Nations Environment Programme, Food and Agriculture Organization of the United Nations.

  6. Marine Connection & Wildlife Trusts, 2007. The south west dolphin report.

Citation

This review can be cited as:

Avant, P. 2008. Tursiops truncatus Bottle-nosed dolphin. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/species/detail/1674

Last Updated: 03/07/2008