[4] The key distinguishing feature is the dolphin's coloration—a white to pale-yellow patch is found behind the dorsal fin on both sides of the body.

[4] The white-sided dolphin's color variations are unique amongst the standard hues of white, grey, black and blue seen on other pelagic cetaceans.

[4] Their body's coloration is well-demarcated, with the chin, throat and belly being white; the flippers, dorsal fin and back are dark-grey to black (with the exception of the yellow patch), and there is a further white patch below the dorsal fin (lying above a lighter, grayish stripe running from the beak, above the eye, down to the tail stock).

[4] Dolphin pod sizes vary by location, with groups averaging 60 in number having been seen close to the Newfoundland coastline, but somewhat smaller east of Iceland.

[4] From the analysis of the stomach contents of stranded animals, fishes, such as herring and mackerel, and squid appear to be the species' main prey.

[7][8][9] 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.

[10] Along the North American east coast the species tends to occur in continental shelf waters, around 100m in depth,[11] and seem to show a preference toward areas of steep slopes and canyons.

[17] 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".

[25] 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.

[12][17] Anthropogenic underwater noise is a potential disturbance to Atlantic white-sided dolphins as they use sounds to communicate and catch prey.

[20] A survey done in the UK showed that the sighting rate of Atlantic white-sided dolphins declines when airguns were firing compared to when they were not.

[20] Persistent organic pollutants (POPs) such as PCBs and organochlorine pesticides (e.g. DDT, DDE) and polybrominated diphenyl ether (PBDE) flame retardants have been identified in body tissues of Atlantic white-sided dolphins throughout their range.

[1] The North and Baltic Sea populations of the Atlantic white-sided dolphin are listed on Appendix II [34] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS).

They are listed on Appendix II[34] as they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.