The Atlantic white-sided dolphin is black on the back, with
dark grey flanks and a long white oval blaze below the dorsal
fin, extending towards the anal area. Above the blaze there
is a yellow-ochre band. The belly is white. They have a black
ring around the eyes. The body is stocky and torpedo-shaped.
The flippers are pointed and sickle-shaped. The dorsal fin
is sickle-shaped and relatively tall. The tail stock is thick.
Adults are 2.25-2.5 m long and weigh about 165 kg (maximum
3 m long, 250 kg (Peet et al, 1992). They have 29-40 pairs
of small, sharp-pointed teeths in each jaw (Evans, 1987).
The Atlantic white-sided dolphin can be found in the temperate
and sub-polar regions of the North Atlantic, from West Greenland,
Iceland and the Barents Sea south to Cape Cod in the west
and Ireland and the North Sea in the East. This is roughly
the same distribution as the white-beaked dolphin, but the
Atlantic white-sided dolphin is somewhat more pelagic. Inshore
they are usually found in groups of 10-60 individuals. Offshore
they are occassionally seen in herds of at least 1,000 animals.
There are some indications, that immature animals and newly
matures males are absent from larger breeding groups, indication
some form of segregation among the herds. This species is
usually found in colder waters (< 12°C, range 1-15°C)
and in areas of relatively low salinity (Selzer and Payne,
Calves are born in spring or mid-summer after a 10 month gestation
period. At birth the calves are 107-122 cm long. Lactation
lasts 18 months. The calving interval is 2-3 years (Minasian
et al, 1984). The (maximum) longevity is probably 27 years
for females and 22 years for males (Klinowska, 1991).
No data is available on the size of the population. The species
is considered to be regionally abundant. In the eastern North
Atlantic the Atlantic white-sided dolphin population size
is estimated to be about 40% of the size of the white-beaked
dolphin population (relative estimate based on sightings.
There is no absolute size estimate for either species) (Klinowska,
There has been drive fisheries for this species in a number
of areas (Mitchell, 1975). Currently, some are taken in Greenland
and the Faeroe Islands. There are incidental catches in fisheries
throughout its range (Klinowska (1991), IWC (1996), Read (1994)).
45 animals were reportedly by-caught in Dutch fisheries in
1993 and 141 in 1994 (IWC, 1996). To date there has been no
captive display of this species. A number of them have been
housed temporarily in rehabilitation facilities in Boston
and Harderwijk after stranding.
The Atlantic white-sided has a widely varied diet. Prey species
include squid, herring, smelt and silver hake, as well as
Recently, one Atlantic white-sided dolphin was seen getting
trapped in a fishing net. Upon entanglement its companions
took off at a speed of about 25 knots, abandoning the entangled
dolphin (Weinrich, 1996)
Evans, P.G.H. (1987)
The natural history of whales and dolphins. Christopher Helm,
International Whaling Commission (1996)
Report of the sub-committee on small cetaceans. Rep. Int.
Whal. Commn. 46:160-179
Klinowska, M. (1991)
Dolphins, Porpoises and Whales of the World. The IUCN Red
Data Book. IUCN, Gland, Switzerland.
Minasian, S.M., Balcomb III, K.C. and Foster, L. (1984)
The world's whales. The complete illustrated guide. Smithsonian
Books, Washington D.C.
Mitchell, E. (1975)
Porpoise, dolphin and small whale fisheries of the world.
Status and problems. IUCN Monograph No. 3. IUCN, Gland, Switzerland
Peet, G., Nijkamp, H., Nelissen, P.-H. and Maas, F.-J. (1992)
Bruinvissen dolfijnen en walvissen van de Noordzee. Uitgeverij
M&P, Weert, the Netherlands.
Read, A.J. (1994)
Interactions between cetaceans and gillnet and trap fisheries
in the Northwest Atlantic. In: W.F. Perrin, G.P. Donovan and
J. Barlow (eds.): Gillnets and cetaceans. Rep. Int. Whal.
Commn. (Special Issue 15):133-147 (SC/O90/G6)
Selzer, L.A. and Payne, P.M. (1988)
The distribution of white-sided (Lagenorhynchus acutus) and
common dolphins (Delphinus delphis) vs. environmental features
of the continental shelf of the Northeastern United States.
Marine Mammal Science 4(2):141-153
Weinrich, M. (1996)
Abandonment of an entangled conspecific by Atlantic white-sided
dolphins (Lagenorhynchus acutus) Marine Mammal Science 12(2):293-296