Northern Ireland's Priority Species

Tursiops truncatus – bottlenose dolphin

 
Tursiops truncatus

Tursiops truncatus Montagu, 1821
Family: Ziphiidae

Bottle-nose dolphins are found in temperate and tropical waters throughout the world. They are regularly seen in the coastal waters of Northern Ireland, usually in groups or herds of 5-30 individuals. Famous for their friendly disposition towards people, bottlenose dolphins often approach boats to bow-ride.

In brief

  • Found in the seas around Northern Ireland
  • Can be seen all year round
  • Listed as a UK Priority species
  • Main threats to the population are accidental capture and drowning in commercial fishing equipment (by-catch) and pollution

Species description
Adult bottle-nose dolphins are 2.5-4m long. Their sturdy, streamlined bodies are dark to light grey on the back and sides, fading to pale grey or white on the lower jaw, throat and belly. The beak is short but noticeable with a lower jaw that sticks out slightly more than the upper jaw. There are between 18 and 26 pairs of pointed, cone-shaped teeth present in the upper and lower jaw. The mouth line curves upward at the back, giving the animal a smiling appearance. The tall, sickle-shaped dorsal fin is located midway along the back.

Life cycle
Bottle-nose dolphins eat 8-15kg of food daily: mainly fish but squid, shrimps and crabs are also taken. Groups of dolphins will often cooperate when hunting and catching schools of fish. Bottle-nose dolphins produce a number of different sounds to communicate with each other; every individual has its own unique identifying whistle. They also use echolocation to determine the shape, size, speed, distance and structure of objects in their surroundings. High frequency sound waves are projected as clicks - when they hit an object, they bounce back to the dolphin who can interpret the returning echo. Mating takes place after a short courtship. Pregnancy lasts for 12 months and a single calf (around 1m long) is born in the summer. Dolphins can live for 25-30 years.

Similar species
Bottlenose dolphins may be confused with Risso’s dolphin. Both species are grey, however Risso’s dolphin is usually heavily scarred and has a rounded head with no beak

How to see this species
Sightings off the coast of Northern Ireland are possible at all times of the year. The best places to see dolphins are headlands and bays when the sea is calm. Along the County Antrim coastline, from Whitehead to Portrush, in Dundrum Bay and Newcastle (both in County Down) and at Portstewart, County Londonderry, are all areas where bottle-nose dolphins are regularly seen.

Current status
The total population of bottle-nose dolphins in the seas around the United Kingdom is about 8,000 individuals. The population around the island of Ireland is approximately 17,500. Recent studies have shown that some inshore bottle-nose dolphins use the entire Irish coast and are not confined to a particular coastal area.

  • Protected under schedule 5 of the Wildlife (Northern Ireland) Order 1985
  • Listed in Schedule 2 of The Conservation of Habitats and Species Regulations 2010
  • Listed in Appendix II of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention)
  • Listed in Appendix II of the Convention on the Conservation of Migratory Species (The Bonn Convention)
  • Covered by the terms of the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS)
  • Listed in Appendix II of CITES
  • Listed in Annex A of EU Council Regulation 338/97 and therefore treated by the EU as if they are on CITES, Appendix I
  • Listed in Annex II and IV (Animal and Plant Species of Community Interest in Need of Strict Protection) of the EC Habitats Directive
  • Listed in Schedule 2 of The Conservation (Natural Habitats, etc.) Regulations (Northern Ireland) 1995

Why is this species a priority in Northern Ireland?

  • Listed as a UK Priority species

Threats/Causes of decline

  • Reduction in fish numbers due to commercial fishing
  • Entanglement in fishing gear (by-catch)
  • Disturbance and/or injury by sea vessels
  • Pollution (chemical and noise)

Conservation of this species

Current action
Bottle-nose dolphins are included in the UK Grouped Species Action Plan for small dolphins, which was published in 1999.

  • Post mortem and tissue studies are carried out on stranded dolphins to establish the cause of death and condition of the animals at the time of death
  • In 2008 the Northern Ireland Environment Agency initiated a cetacean monitoring programme to provide information on the distribution and relative abundance of cetaceans in Northern Ireland waters. The information collected will enable the future selection of marine protected areas for cetaceans

Proposed objectives/actions

  • Avoid accidental harm to whales and dolphins when present in Northern Ireland waters
  • Contribute to international measures for the conservation of whales and dolphins
.

What you can do
To report bottle-nose dolphin sightings to CEDaR, Telephone 028 9039 5264 or email cedar.info@nmni.com.

Further information

Links
Irish Cetacean Review 2000-2009, The Irish Whale and Dolphin Group

UK Grouped Species Action Plan for small dolphins

Joint Nature Conservation Committee (JNCC) priority species page

NBN Gateway: Bottle-nosed Dolphin (Tursiops truncatus) grid map

Irish Whale and Dolphin Group

Cetaceans of Norhtern Ireland - Sea Watch Foundation

Literature

Text written by:
Angela Ross

iNaturalist: Species account : iNaturalist World Species Observations database