Atlantic White-sided Dolphin

Atlantic White sided Dolphin: Lagenorhynchus acutus

IUCN Status: Least concern

Status and Distribution summary:

Current population estimates exceed 100,000 animals. Found in cool temperate and cold waters of the North Atlantic, where it shows a preference for shelf slopes, seamounts and canyons.


Historically taken for food in Norway and Eastern Canada, now only in Faroe Islands where from 150-750 are killed each year in small whale drives (see Long-finned Pilot Whale).

Other threats:

Is reported to suffer by-catch in fisheries off western Ireland in significant numbers. May be prone to by-catch as has been observed feeding around hauled nets.

Where is it seen?

Most common off northwestern Scotland, however it has been recorded on the continental shelf slope in the northern Bay of Biscay.

Frequency of Sightings:

Rarely seen from the ferry though it has been recorded in Northern Biscay, including off Ile d'Ouessant.


Large and robust with thick tail stock 1.9-2.8m

  • Blackish to grey upper body. Whitish underneath
  • Pale gray and black flank bands and a well defined  white blaze on flank beneath dorsal fin with yellow/mustard blaze behind this on tail stock.
  • Very short beak with black upperside.
  • Tall dark falcate fin.


Usually in groups of 5-50 inshore with pods of up to 1,000 recorded offshore.

Fast swimmer and often breaches and lobtails.

Fairly shy but will occasionally bow ride boats and large whales.

Confusion species:

  • White-beaked Dolphin which is heavier with more white but less distinct markings and no yellow blaze and Short-beaked Common Dolphin which can be differentiated by its smaller size and distinctive hourglass pattern.