Length: 2.5 – 2.8 m (8 – 9’) 
Weight: 200 – 230 kg (400 – 510lbs)
Population size in Canada: 40,000 animals in the western Atlantic
Population size in World: possibly 300,000 animals in the North Atlantic
Conservation status in Canada: Not at Risk (COSEWIC)
Conservation status in World: Lower risk: least concern (IUCN)

Classification

Latin Name: Lagenorhynchus acutus
Other Names: Jumper, Springer, Lag, Atlantic White-sided Porpoise
Suborder: Odontocete (Toothed Whale)
Family: Delphinidae

Field Identification
  • up to 2.8 m in length
  • one blowhole
  • robust body, thick tail stock
  • back dark grey, grey stripe along flanks, white belly
  • white patch below dorsal fin, yellowish-tan patch on tail stock behind dorsal fin
  • short, thick beak, dark above & white below
  • black eye ring
  • tall falcate (curved) dorsal fin
  • acrobatic & a fast swimmer
  • will ride bow waves of boats & large whales
  • group size 5-50 (1-100), schools of up to 1,000 recorded offshore
Description

Atlantic white-sided dolphins are a robust dolphin with dramatic colouration and patterning, most noticeably a yellow-brown stripe on the flanks from below the dorsal fin to the flukes.  The back and dorsal fin are black or very dark grey, and patches of lighter grey and white are seen on the flanks. A distinct white patch is located below the dorsal fin. The dorsal fin is very tall and curved and located mid-body. Atlantic white-sided dolphins have a robust body with a very short, thick beak. Individuals can reach up to 2.8 m in length with males being slightly larger than same age females.

Life History

Females reach sexual maturity at an age of 6 to 12 years (2 – 2.2 m), and males 7 to 11 years (2.15 – 2.3 m).  After an 11-month gestation, a single 1.2 m calf is born and nursed for 18 months or more. Peak calving months appear to be between June-July for this species and females typically give birth every other year. Individuals up to the age of 30 have been recorded.

Distribution

Atlantic white-sided dolphins are found in coastal, shelf and oceanic waters on both sides of the Atlantic.  The species ranges from approximately Cape Cod to Newfoundland, Labrador and southern Greenland in the west, and from Brittany to the Norwegian Sea and Iceland in the east.

Diet

Prey species include small schooling fish (e.g., herring, mackerel, sandlance) and squid.

Behaviour

These dolphins are very acrobatic, with activities such as bow-riding and leaps commonly observed. These dolphins are seen in groups of a few individuals up to several thousand animals and there is some evidence for segregation by sex and age. Mass strandings of groups of tens to more than 100 animals have been documented, including several in the Maritime Provinces.

Population size

Population sizes are difficult to determine as these animals are so wide spread. It is thought that there are about 300,000 animals in the North Atlantic.

Threats

Large numbers of these dolphins are caught as bycatch in fishing nets and there are a number of animals taken in the Faroe Islands pilot whale drive fishery. Chemical and acoustic pollution, habitat degradation and harassment may also be major issues for Atlantic white-sided dolphins.

References

Kingsley MCS, Reeves RR (1998) Aerial surveys of cetaceans in the Gulf of St. Lawrence in 1995 and 1996. Canadian Journal of Zoology; 76:1529-1550.

Palka D, Read A., Potter C (1997) Summary of knowledge of white-sided dolphins (Lagenorhynchus acutus) from US and Canadian Atlantic waters. Rep Int Whal Comm 47:729-734.

Cipriano F (2002) Atlantic white-sided dolphin. In: Encyclopedia of marine mammals (Perrin WF, Würsig B, Thewissen JGM, eds.) Academic Press, San Diego, 49-51.