(Gray, 1828) - Atlantic white-sided dolphin
Atlantic white-sided dolphins have the typical Lagenorhynchus body shape which is a stocky body with a short thick snout and tall falcate dorsal fin. The tail stock is strongly deepened.
The colour pattern is complex. The back and upper sides, upper jaw, dorsal fin, flippers, and flukes are black or dark grey, and a dark line runs backwards from the beak and surrounds the eye. The lower jaw and belly, as far as the urogenital area, are white. In between, the sides from just ahead of the eye to the base of the flukes are light grey. Along the upper margin of the grey side is a white patch from below the dorsal fin to midway along the tail stock. There is another narrow band, this one ochre in colour, at the lower margin of the dark upper flank, from the middle of the tail stock to just in front of the flukes.
Each tooth row contains 30 to 40 pointed teeth.
Can be confused with
Confusion is most likely with the white-beaked dolphin, which shares a nearly identical range. The 2 can be distinguished most easily by colour-pattern differences.
Adult Atlantic white-sided dolphins reach 2.8 m (males) or 2.5 m (females) in length and about 235 kg (males) and 182 kg (females) in weight. Newborns are 1.1 to 1.2 m.
Atlantic white-sided dolphin are found in cold temperate to subpolar waters of the North Atlantic, from about New England in the west and France in the east, north to southern Greenland, Iceland, and southern Norway. They rarely enter the Baltic Sea. The preferred habitat appears to be deep waters of the outer continental shelf and slope.
Biology and Behaviour
Herds of up to several hundred are seen, and there is some age and sex segregation of herds. Older immature individuals are not generally found in reproductive herds of mature females and young. Atlantic white-sided dolphins are lively and acrobatic. Much of what we know of this species' biology comes from examination of individuals from mass strandings.
Calves are born in summer, with a peak in June and July.
Atlantic white-sided dolphins feed on small schooling fish and squid. They often feed in association with large whales.
Some hunting for this species occurred in the past, especially in Norway. Some are still taken in Greenland, the Faeroe Islands, and eastern Canada. Incidental kills in gillnets and other fishing gear is known from both sides of the Atlantic. Despite this exploitation, Atlantic white-sided dolphins are very abundant, at least off the northeast coast of North America.