Atlantic White-Sided Dolphin
Lagenorhynchus acutus
Population size
Life Span
22-27 years
kg lbs 
m ft 

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


A large dolphin with robust body, the Atlantic white-sided dolphin is so called due to the pale white patch on the sides below the dorsal fin. The animal exhibits the identifying yellow spot by the rear of the flanks. This dolphin is sometimes taken for the white-beaked dolphin, though the back of the latter is much lighter in color. Also, the species has similar coloration with the common dolphin - grey, white, black and yellow; these two dolphin species are sometimes confused, though, unlike the common dolphin, the Atlantic white-sided dolphin does not have the identifying hourglass coloration.



The species inhabits cool temperate and sub-arctic waters of the North Atlantic, along the continental shelf. The Atlantic white-sided dolphins usually occur in waters with low salinity, being found at the depth of 40 - 270 meters. They can often be seen in the UK waters, especially around the Hebrides and the Northern Isles as well as northern parts of the North Sea. They also inhabit waters offshore the west coast of Ireland and can occur in the south-western waters of the island, close to the English Channel.

Atlantic White-Sided Dolphin habitat map

Climate zones

Atlantic White-Sided Dolphin habitat map
Atlantic White-Sided Dolphin
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Habits and Lifestyle

These dolphins are highly social animals, gathering into large groups of up to several hundred animals. Meanwhile, those in the western Atlantic, and especially along the Canadian Atlantic coast, usually form small herds, consisting of 6 - 8 dolphins, whereas those, living in the inshore areas, live in larger groups of 10 - 60 individuals. At feeding periods, these dolphins are known to share their habitat with fin whales, humpback whales, long-finned pilot whales and other cetacean species. The Atlantic white-sided dolphin is a fast swimmer and a very active animal, often splashing the tail flukes onto the water surface with a noise. Bow-riding is a common behavior in this species: this is when the animal rides waves at the front of a boat, and, sometimes, a large whale. Also, the Atlantic white-sided dolphins can sometimes be observed breaching or clearing the water.

Group name
Seasonal behavior

Diet and Nutrition

Atlantic white-sided dolphins are carnivores (piscivores). They mainly feed upon herring, smelt, hake, shrimp as well as squid.

Mating Habits

births occur in June-July
10 months
1 calf
18 months

Currently, there is no information about the mating system of this species. However, it is known, that the gestation period lasts about 10 months, yielding a single baby, usually in June-July. Females give birth with an interval of 2 - 3 years. By the age of 18 months, the calf is weaned. Male individuals reach sexual maturity, when they are 2.1 - 2.4 meters in length, whereas females are sexually mature at a length of 1.94 - 2.22 meters, when they are possibly about 12 years old.


Population threats

Presently, the species hugely suffer from hunting as well as drowning as a result of being entangled in fishing tackles. Other notable concerns to the population of the Atlantic white-sided dolphin are environmental changes and chemical pollution.

Population number

According to IUCN, the Atlantic white-sided dolphin is abundant and widespread throughout its range but no overall population estimate is available. However, there are estimates of its populations in specific areas: off the eastern North American shoreline - 51,640 dolphins; off the west coast of Scotland - about 96,000 dolphins; in the western North Atlantic - about 27,000 dolphins and in the Gulf of St. Lawrence - 11,740 dolphins. Currently Atlantic white-sided dolphins are classified as Least Concern (LC) on the IUCN Red List.

Fun Facts for Kids

  • The dolphin exhibits yellowish-tan colored bands on its sides.
  • The animal is capable of remaining submerged for up to 5 minutes when diving at hunting.
  • The species is able to navigate the area, detect prey and successfully hunt due to using echolocation.
  • The Atlantic white-sided dolphin has 30 - 40 pairs of teeth, which enable the animal to easily catch and grab prey so that it cannot escape.
  • Dolphins are known to be highly intelligent animals. They demonstrate culture - a phenomenon, which has been thought to be typical for humans, though nowadays it's recognized to be common in many animal species.
  • Dolphins use various tools in their daily life. For example, in order to protect themselves at hunting, they cover their snouts with sponges. These intelligent animals are also known to teach their offspring to use these tools.
  • Dolphins are widely known as altruistic animals. Aiding each other in distress is common in dolphins: they can be seen helping injured individuals to get to the surface in order to breath. Moreover, they show compassion not only to individuals of their kind but also to other species, including whales and even humans.
  • Dolphins are also very curious animals. They usually display extremely playful behavior and can often be observed play-fighting with each other. In addition, they can play with seaweed as well as other animals, including dogs.

Coloring Pages


1. Atlantic White-Sided Dolphin Wikipedia article -
2. Atlantic White-Sided Dolphin on The IUCN Red List site -

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