Lagenorhynchus acutus - Atlantic white-sided dolphin:

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Summary Information
Living Organisms / Animalia / Craniata / Mammalia / Cetacea / Delphinidae / Lagenorhynchus / Species
Alternative Names Delphinus (Grampus) acutus Gray, 1946; Orkney
Description Elongated ochre band on flank (D23).

Large robust dolphin with short beak, large, often erect, sickle-shapes dorsal fin, black back and distinctive long white patch on side extending caudally as narrow yellow/ochre band.(B142)




  • 2.52.7m / 8-9ft (D23)
  • Female about 2.25m. Male about 2.5m (B142)
  • New-born: Length about 110cm (v)


External Appearance:

  • Body: stout torpedo shape.
  • Head: Snout rounded, beak short, black. Teeth sharp-pointed, small (about 5mm diameter), 29-40 pairs per jaw. Thin black line from rostrum to black eye patch.
  • Dorsal: black, flanks dark grey, with white elongated oval blaze extending from below dorsal fin to region above anus. Yellow/ochre elongated band continuing from dorsal edge of white band caudally towards tail.
  • Abdomen: white.
  • Narrow dark stripe from angle of mouth to flippers.
  • Flippers: pointed sickle-shape, black.
  • Fin: central along back, sickle-shaped, relatively tall and more erect in adult males.
  • Tail: stock very thick, narrowing close to tail flukes - strongly concave trailing edge, slight notch.


Range and Habitat World: North Atlantic and Atlantic Arctic.From central West Greenland, Iceland and southern Berents Sea southwards to Cape Cod and south-western Ireland.
  • Britain & Ireland: north Scottish waters including northern North Sea and south down Atlantic seaboard to southwest Britain and Ireland.

(B51, B142)


  • Around Britain: most commonly seen August to October; rarely seen in winter (B142).


  • Not particularly coastal; mainly in offshore waters (B142).
Further Information Food:
  • Fish - e.g. Micromesistius, Clupea, Gadus, Scomber, Merlangius, Osmerus, Trisopterus and Merluccius spp.
  • Squid - Loligo spp.
  • Gammarid crustaceans.


Feeding Behaviour: --


  • Births mainly early summer (May to July).
  • Gestation 10-12 months.
  • Lactation about 18 months.
  • Calving interval may be about 2-3 years.
  • (B142)

Breeding Behaviour: --


  • Fast swimmer.
  • Sometimes breaches.
  • (B142)

Social Behaviour:

  • Around Britain mainly in groups of less than ten individuals.
  • Herds may contain 50-100 individuals.
  • Mixed age and sex.
  • (B142)

Organisations (UK Contacts):

Electronic Library (further reading):

General Legislation:

Individual techniques:

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