The Atlantic white-sided dolphin (Leucopleurus acutus) is a distinctively coloured dolphin found in the cool to temperate waters of the North Atlantic Ocean.

Description

thumb|left|An Atlantic white-sided dolphin off the coast of Cape Ann, Massachusetts

The Atlantic white-sided dolphin is a relatively small dolphin. At birth, calves measure just over a meter long; adult males grow to about , and females to about , weighing between 180 and 230 kg (400- 510 lb) once fully grown. The gestation period is 11 months and lactation lasts for about 18 months — both typical figures for dolphins. In 2008, sightings of Atlantic white-sided dolphins, as well as the melon-headed whale, were documented off South Carolina after a few strandings had taken place in the area at the time. Along the North American east coast the species tends to occur in continental shelf waters, around 100m in depth, and seem to show a preference toward areas of steep slopes and canyons. They are associated with the colder, slightly less saline waters in the northern Atlantic, compared to for example common dolphins that are found in warmer, slightly more saline waters of the North Atlantic, though it is unclear whether this is due to preferences or if these factors influence prey supply.

Behaviour

Foraging

The diet of Atlantic white-sided dolphins mainly consists of herring, hake and squid. The pod's size can vary, from several dozen to several hundred individuals, though the average size is around 50. However, studies have shown there to be little familial relation between members of a group, appearing more as a social pod traveling for "safety in numbers". Researchers in different parts of their range have found that individuals were, mostly, unrelated to one another. Juveniles spend at least some time in separate social groups, away from their parents, prior to weaning. It is suggested that vocalisation is used for communication as noise production increases during socialising. they have also been known to display violent behavior towards harbor porpoises, attacking them until they eventually succumb to their wounds (a similar behavior as observed in bottlenose dolphins).

Migration

Atlantic white-sided dolphins do not undertake specific seasonal migration. In 2025 the Atlantic white-sided dolphin was therefore moved to its own genus, Leucopleurus.

Population status

The estimations for the U.S. shelf and shelf-edge water suggest that the population size is about 300,000. These have ceased in recent years, although they still occur to a lesser extent from the Faroe Islands, where the meat and blubber are in high regard as food. Reported catches in the years vary, though individual years suddenly stand out, such as in 2002, where the number reported killed was 773, and in 2017, when 488 were killed.

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|+ Annual number taken of white-sided dolphin in the Faroe Islands in the period 1980-2009 They have also been reported to get caught in pelagic or near surface trawl or drift nets. Males had higher levels of PCBs suggesting that females pass some of the contamination to offspring during lactation[30]. Similarly to other species, studies have identified heavy metals in Atlantic white-sided dolphins including cadmium levels higher than in other dolphin species in southern latitudes. The full effect of this contamination is currently unknown.

Conservation status

The International Union of the Conservation of Nature (IUCN) currently classifies Atlantic white-sided dolphins as Least Concern. of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). They are listed on Appendix II These species of dolphin are known to fall victims to in a polluted environment, a study from 1997 confirmed that the British and Irish populations of Atlantic white-sided dolphins to succumb to these effects.

In addition, the Atlantic white-sided dolphin is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS).

See also

  • List of cetaceans
  • Marine biology

References

  • Atlantic white-sided Dolphin by Frank Cipriano, Encyclopedia of Marine Mammals pp49–51
  • National Audubon Society: Guide to Marine Mammals of the World
  • Encyclopedia of Marine Mammals
  • Atlantic white-sided dolphin at ARKive

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