Atlantic White-sided Dolphin
Encyclopedia
The Atlantic White-sided Dolphin (Lagenorhynchus acutus) is a distinctively coloured dolphin
found in the cool to temperate waters of the North Atlantic Ocean
.
for 'pointed' and refers to the sharply pointed dorsal fin
. L. acutus is one of six oceanic dolphins in the genus Lagenorhynchus
.
The key distinguishing feature is the white to pale yellow patch found behind the dorsal fin of the dolphin on each side. This variation in colour to the Atlantic White-sided Dolphin is unique amongst the mixtures of white, greys and blues of other pelagic cetaceans. The rest of the body's coloration is well demarcated: the chin, throat and belly are white; the flippers, dorsal fin
and back are dark grey to black with the exception of the yellow patch; there is a further white patch below the dorsal fin, lying above a light grey stripe that runs from the beak, above the eye and down to the tail stock.
Dolphin group sizes vary by location, with groups averaging 60 in number close to the Newfoundland shores, but rather smaller east of Iceland
. From the analysis of the stomach
contents of stranded animals, fish such as herring
and mackerel
and squid
appear to form the species' main diet. The Atlantic White-sided Dolphin is fairly acrobatic and keen to interact with boats, however it is not as wildly gregarious as the White-beaked
and Common Dolphin
s.
, the triangular area of sea between the United Kingdom
, Iceland
and Greenland
and the North Sea
. The total population is believed to be 200-300,000 individuals.
Historically, Atlantic White-sided Dolphins were killed in drives conducted from Norway and Newfoundland. 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.
Reported catches in the years from 1995 to 1998 were 157, 152, 350, and 438, respectively (Bloch and Olsen 1998, 1999; Bloch et al. 1997, 2000). In 2002, the number reported killed was 774.
). They are listed on Appendix II as they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
In addition, the Atlantic white-sided dolphin is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS
).
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
found in the cool to temperate waters of the North Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
.
Taxonomy
The Atlantic White-sided Dolphin was named by Gray in 1828. The specific name acutus comes from the LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for 'pointed' and refers to the sharply pointed dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
. L. acutus is one of six oceanic dolphins in the genus Lagenorhynchus
Lagenorhynchus
Lagenorhynchus is a genus in the order Cetacea, traditionally containing six species:* white-beaked dolphin, Lagenorhynchus albirostris* Atlantic white-sided dolphin, Lagenorhynchus acutus...
.
Physical description
The dolphin is slightly larger than most other oceanic dolphins. It is just over a meter in length at birth, growing to about 2.8 m (9.2 ft) (males) and 2.5 m (8.2 ft) (females) at maturity. It weighs 200 – once fully-grown. Females reach sexual maturity at between 6 and 12 years, and males between 7 and 11 years. The gestation period is 11 months and lactation lasts for about a year and a half - both typical figures for dolphins. Individuals are known to live for up to 22 years (males) and 27 years (females). Also 25 years approximately.The key distinguishing feature is the white to pale yellow patch found behind the dorsal fin of the dolphin on each side. This variation in colour to the Atlantic White-sided Dolphin is unique amongst the mixtures of white, greys and blues of other pelagic cetaceans. The rest of the body's coloration is well demarcated: the chin, throat and belly are white; the flippers, dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
and back are dark grey to black with the exception of the yellow patch; there is a further white patch below the dorsal fin, lying above a light grey stripe that runs from the beak, above the eye and down to the tail stock.
Dolphin group sizes vary by location, with groups averaging 60 in number close to the Newfoundland shores, but rather smaller east of Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
. From the analysis of the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
contents of stranded animals, fish such as herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
and mackerel
Mackerel
Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be...
and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
appear to form the species' main diet. The Atlantic White-sided Dolphin is fairly acrobatic and keen to interact with boats, however it is not as wildly gregarious as the White-beaked
White-beaked Dolphin
The White-beaked dolphin is a marine mammal belonging to the family Delphinidae in the suborder Odontoceti .-Taxonomy:...
and Common Dolphin
Common dolphin
The common dolphin is the name given to two species of dolphin making up the genus Delphinus.Prior to the mid-1990s, most taxonomists only recognised one species in this genus, the common dolphin Delphinus delphis...
s.
Population and distribution
The species is endemic to the North Atlantic Ocean. Areas of particularly high population density include the shores of Newfoundland and Cape CodCape Cod
Cape Cod, often referred to locally as simply the Cape, is a cape in the easternmost portion of the state of Massachusetts, in the Northeastern United States...
, the triangular area of sea between the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
and the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
. The total population is believed to be 200-300,000 individuals.
Human interaction
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
, where the meat and blubber are in high regard as food.
Reported catches in the years from 1995 to 1998 were 157, 152, 350, and 438, respectively (Bloch and Olsen 1998, 1999; Bloch et al. 1997, 2000). In 2002, the number reported killed was 774.
Conservation
The North and Baltic Sea populations of the Atlantic white-sided dolphin are listed on Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMSBonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
). They are listed on Appendix II as they have an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
In addition, the Atlantic white-sided dolphin is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS
ASCOBANS
ASCOBANS is a regional agreement on the protection of small cetaceans that was concluded as the “Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas” under the auspices of the UNEP Convention on Migratory Species, or Bonn Convention, in September 1991 and came into force...
).
External links
- Atlantic White-sided Dolphin at ARKiveARKiveARKive is a global initiative with the mission of "promoting the conservation of the world's threatened species, through the power of wildlife imagery", which it does by locating and gathering films, photographs and audio recordings of the world's species into a centralised digital archive. Its...
- Convention on Migratory Species page on the Atlantic white-sided dolphin
- Official website of the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas