Right whale dolphin
Encyclopedia
Right whale dolphins are cetaceans belonging to the genus Lissodelphis. It contains the Northern Right Whale Dolphin
(Lissodelphis borealis) and the Southern Right Whale Dolphin
(Lissodelphis peronii). These cetaceans are predominantly black, white beneath, and one of the few without a dorsal fin
or ridge. They are smaller members of the delphinid family, oceanic dolphin
s, and very slender. Despite scientists being long acquainted with the species (the Northern species was identified by Peale
in 1848 and the Southern by Lacépède in 1804), little is known about them in terms of life history and behaviour.
Northern males are about 220 cm long at sexual maturity. Females are 200 cm. Both sexes become mature at about 10 years. New-born Right Whale Dolphins are about half the length of their parents. The Southern species is typically larger (up to 250 cm) and heavier (up to 100 kg compared with the Northern's maximum of 80–90kg). The dolphins live for about 40 years.
is widely distributed in the temperate North Pacific in a band running from Kamchatka
and mainland Japan
in the west to British Columbia
down to the Baja California peninsula
in the east. It is not known with certainty if they follow a migratory pattern. However, individuals have been observed close to the California
n shore following their main food source, squid
, in winter and spring. Such sightings have not been recorded in summer. Otherwise these dolphins are pelagic. No global population estimates exist. There are an estimated 14,000 individuals close to the North American shoreline.
The Southern Right Whale Dolphin
has a circumpolar distribution running from about 40° to 55°. They are sighted in the Tasman Sea
in particular.
s and Pilot Whale
s (in the south) and Pacific White-sided Dolphin
s (in the north). These dolphins are some of the fastest swimmers (in excess of 40 km/h). They can by turns become very boisterous and breach and tail-slap or become very quiet and almost undetectable at sea. At high speed they can leap up to 7 metres across the ocean's surface in a graceful bouncing motion.
The species will generally avoid boats, but bow-riding has been recorded on occasion.
No strandings have been recorded for the Northern species. There has been one recorded instance of 77 Southern Right Whale Dolphins stranding on Chatham Island.
s introduced at that time. Gillnets were banned by the United Nations
in 1993. Conservation campaigners work vigorously to try to ensure these bans are retained.
Attempts have been made to keep Northern Right Whale Dolphins in aquaria. In most cases they have died for unknown reasons within three weeks. Exceptionally, one animal survived 15 months in captivity. There have been no attempts to bring a Southern Right Whale Dolphin into captivity.
Northern Right Whale Dolphin
The Northern right whale dolphin is a small and slender species of marine mammal found in the North Pacific Ocean. The Northern right whale dolphin travels in groups of up to 2000, often with other cetaceans, in deep waters of the North Pacific...
(Lissodelphis borealis) and the Southern Right Whale Dolphin
Southern Right Whale Dolphin
The southern right whale dolphin, Lissodelphis peronii, is a small and slender species of mammal found in cool waters of the southern hemisphere...
(Lissodelphis peronii). These cetaceans are predominantly black, white beneath, and one of the few without a 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...
or ridge. They are smaller members of the delphinid family, oceanic dolphin
Oceanic dolphin
Oceanic dolphins are the members of the Delphinidae family of cetaceans. These marine mammals are related to whales and porpoises. They are found worldwide, mostly in the shallower seas of the continental shelves...
s, and very slender. Despite scientists being long acquainted with the species (the Northern species was identified by Peale
Titian Peale
Titian Ramsay Peale was a noted American artist, naturalist, entomologist and photographer. He was the sixteenth child and youngest son of noted American naturalist Charles Willson Peale.-Biography:...
in 1848 and the Southern by Lacépède in 1804), little is known about them in terms of life history and behaviour.
Physical description
Both species have slender bodies, small, pointed flippers and a small fluke. Conspicuously, neither species has a dorsal fin. The Northern Right Whale Dolphin is the only dolphin in the Pacific with this property. Similarly, the Southern is the only finless dolphin in the southern hemisphere. The two species can be readily distinguished (apart from the geographical separation in their ranges) by the extent of the whiteness on the body. Both have white bellies; however, the area of white coloration on the Southern species covers much more of the body - including the flanks, flippers, beak and forehead.Northern males are about 220 cm long at sexual maturity. Females are 200 cm. Both sexes become mature at about 10 years. New-born Right Whale Dolphins are about half the length of their parents. The Southern species is typically larger (up to 250 cm) and heavier (up to 100 kg compared with the Northern's maximum of 80–90kg). The dolphins live for about 40 years.
Distribution
The Northern Right Whale DolphinNorthern Right Whale Dolphin
The Northern right whale dolphin is a small and slender species of marine mammal found in the North Pacific Ocean. The Northern right whale dolphin travels in groups of up to 2000, often with other cetaceans, in deep waters of the North Pacific...
is widely distributed in the temperate North Pacific in a band running from Kamchatka
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
and mainland Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
in the west to British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
down to the Baja California peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...
in the east. It is not known with certainty if they follow a migratory pattern. However, individuals have been observed close to the California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
n shore following their main food source, 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...
, in winter and spring. Such sightings have not been recorded in summer. Otherwise these dolphins are pelagic. No global population estimates exist. There are an estimated 14,000 individuals close to the North American shoreline.
The Southern Right Whale Dolphin
Southern Right Whale Dolphin
The southern right whale dolphin, Lissodelphis peronii, is a small and slender species of mammal found in cool waters of the southern hemisphere...
has a circumpolar distribution running from about 40° to 55°. They are sighted in the Tasman Sea
Tasman Sea
The Tasman Sea is the large body of water between Australia and New Zealand, approximately across. It extends 2,800 km from north to south. It is a south-western segment of the South Pacific Ocean. The sea was named after the Dutch explorer Abel Janszoon Tasman, the first recorded European...
in particular.
Behaviour
Both species are highly gregarious. They move in pods of several hundred individuals and sometimes congregate in groups of 3000. The groups may also contain Dusky DolphinDusky Dolphin
The dusky dolphin is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, but current scientific consensus is that they are distinct species...
s and Pilot Whale
Pilot whale
Pilot whales are cetaceans belonging to the genus Globicephala. There are two extant species, the long-finned pilot whale and the short-finned pilot whale . The two are not readily distinguished at sea and analysis of the skulls is the best way to tell the difference between them...
s (in the south) and Pacific White-sided Dolphin
Pacific White-sided Dolphin
The Pacific White-sided Dolphin is a very active dolphin found in the cool to temperate waters of the North Pacific Ocean.-Taxonomy:...
s (in the north). These dolphins are some of the fastest swimmers (in excess of 40 km/h). They can by turns become very boisterous and breach and tail-slap or become very quiet and almost undetectable at sea. At high speed they can leap up to 7 metres across the ocean's surface in a graceful bouncing motion.
The species will generally avoid boats, but bow-riding has been recorded on occasion.
No strandings have been recorded for the Northern species. There has been one recorded instance of 77 Southern Right Whale Dolphins stranding on Chatham Island.
Conservation
Neither species is hunted and the long-term survival of the species is currently assessed to be secure under present conditions. However tens of thousands of the northern species were killed in the 1980s due to them becoming caught in oceanic drift gillnetGillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s introduced at that time. Gillnets were banned by the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
in 1993. Conservation campaigners work vigorously to try to ensure these bans are retained.
Attempts have been made to keep Northern Right Whale Dolphins in aquaria. In most cases they have died for unknown reasons within three weeks. Exceptionally, one animal survived 15 months in captivity. There have been no attempts to bring a Southern Right Whale Dolphin into captivity.