Australian Snubfin Dolphin
Encyclopedia
The Australian snubfin dolphin (Orcaella heinsohni) is a dolphin
found off the northern coasts of Australia
. It closely resembles the Irrawaddy dolphin
(of the same genus, Orcaella
) and was not described as a separate species until 2005. The Australian snubfin is tri-coloured, while the Irrawaddy dolphin only has two colours on its skin. The skull and the fins also show minor differences between the two species.
, "for his pioneering work on northeast Australian odontocetes, including the collection and initial analysis of Orcaella heinsohni specimens which form the basis for much of our knowledge of the new species".
New species of large mammals are quite rarely described nowadays, and those that are usually from remote areas - such as the Saola
- or are otherwise rarely encountered, see for example Perrin's beaked whale
, or the spade-toothed whale which is only known from a few bones cast ashore. In fact, the Australian snubfin is the first new dolphin species to be described in 56 years. It is unusual among recently described mammals in that a population is accessible for scientific study.
Nonetheless, the existence of snubfin dolphins in the waters of northern Australia had only become known in 1948, when a skull was found at Melville Bay
(Gove Peninsula
, Northern Territory
). This individual apparently had been caught and eaten by aboriginal
s. However, the discovery remained unnoted until discussed by Johnson (1964), and soon thereafter a Dutch skipper had his observations of the then-unrecognized species published.
Two scientists, Isabel Beasley of James Cook University
and Peter Arnold of Museum of Tropical Queensland
, took DNA
samples from the population of dolphins off the coast of Townsville, Queensland
, and sent them to the National Oceanic and Atmospheric Administration
's Southwest Fisheries Science Center in La Jolla, California. The results showed George Heinsohn was correct in his hypothesis that the Townsville population was a new species.
The holotype
QM
JM4721 (JUCU MM61) is the skull and some other bones of an adult male found drowned in a shark net at Horseshoe Bay
, Queensland
, on 21 April 1972. It was about 11 years old at the time of its death.
Orcaella brevirostris, O. heinsohni is subtly tri-coloured: brownish on the top, lighter brown along the sides, and a white belly; the Irrawaddy dolphin, on the other hand, is uniformly slate grey except for the white belly. The new species has a rounded forehead, very unlike other dolphin species in Australia, and the very small, "snubby" dorsal fin distinguishes it from other dolphins in its range. The lack of a groove on each side of the back and the presence of a neck crease further distinguishes this species from its relative.
off Townsville, about 200 individual snubfin dolphins were found. The range of the species is expected to extend to Papua New Guinea
; that is, O. heinsohni is endemic to the northern half of the Sahul Shelf
, but that the majority live in Australia
n waters. They are not thought to be common, and are being given a high conservation
priority. Its IUCN classification of "data deficient" refers to this species and the Irrawaddy dolphin combined (Cetacean Specialist Group 1996). Threats include drowning in fishery and antishark nets; while some hunting by indigenous people probably occurs (as evidenced by the 1948 specimen), this is likely to be insignificant compared to the threat posed by drowning.
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. In addition, Australian snubfin dolphin is covered by Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).
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 off the northern coasts of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It closely resembles the Irrawaddy dolphin
Irrawaddy dolphin
The Irrawaddy dolphin is a euryhaline species of oceanic dolphin found in discontinuous subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia.-Etymology and taxonomic history:...
(of the same genus, Orcaella
Orcaella
The snubfin dolphins are a genus of dolphins containing two members: the Irrawaddy Dolphin and Australian Snubfin Dolphin. The genus was long believed to be monotypic with the only species being the Irrawaddy Dolphin; however, in 2005, genetic analysis showed that the Australian Snubfin Dolphin is...
) and was not described as a separate species until 2005. The Australian snubfin is tri-coloured, while the Irrawaddy dolphin only has two colours on its skin. The skull and the fins also show minor differences between the two species.
Taxonomy
The taxonomic name, Orcaella heinsohni, was chosen in honor of George Heinsohn, an Australian biologist who worked at James Cook UniversityJames Cook University
James Cook University is a public university based in Townsville, Queensland, Australia. The university has two Australian campuses, located in Townsville and Cairns respectively, and an international campus in Singapore. JCU is the second oldest university in Queensland—proclaimed in 1970—and the...
, "for his pioneering work on northeast Australian odontocetes, including the collection and initial analysis of Orcaella heinsohni specimens which form the basis for much of our knowledge of the new species".
New species of large mammals are quite rarely described nowadays, and those that are usually from remote areas - such as the Saola
Saola
The Saola, Vu Quang ox or Asian unicorn, also, infrequently, Vu Quang bovid , one of the world's rarest mammals, is a forest-dwelling bovine found only in the Annamite Range of Vietnam and Laos...
- or are otherwise rarely encountered, see for example Perrin's beaked whale
Perrin's Beaked Whale
Perrin's beaked whale is the newest species of beaked whale to be described. The first two specimens were found in May 1975 stranded on the California coast, with two more specimens being found in 1978 and 1979, and the last in September 1997...
, or the spade-toothed whale which is only known from a few bones cast ashore. In fact, the Australian snubfin is the first new dolphin species to be described in 56 years. It is unusual among recently described mammals in that a population is accessible for scientific study.
Nonetheless, the existence of snubfin dolphins in the waters of northern Australia had only become known in 1948, when a skull was found at Melville Bay
Melville Bay
Melville Bay , is a large bay off the coast of northwestern Greenland. Located to the north of the Upernavik Archipelago, it opens to the south-west into Baffin Bay. Its Kalaallisut name, Qimusseriarsuaq, means "the great dog sledding place"....
(Gove Peninsula
Gove Peninsula
The Gove Peninsula is at the northeastern corner of Arnhem Land in the Northern Territory of Australia. The peninsula became strategically important during World War II when an airforce base was constructed at what is now Gove Airport. The peninsula was named after Pilot Officer William Gove, who...
, Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
). This individual apparently had been caught and eaten by aboriginal
Indigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....
s. However, the discovery remained unnoted until discussed by Johnson (1964), and soon thereafter a Dutch skipper had his observations of the then-unrecognized species published.
Two scientists, Isabel Beasley of James Cook University
James Cook University
James Cook University is a public university based in Townsville, Queensland, Australia. The university has two Australian campuses, located in Townsville and Cairns respectively, and an international campus in Singapore. JCU is the second oldest university in Queensland—proclaimed in 1970—and the...
and Peter Arnold of Museum of Tropical Queensland
Museum of Tropical Queensland
The Museum of Tropical Queensland is a museum of natural history, archaeology and history located in Townsville, Queensland, Australia. It is located in the same complex as the Reef HQ Aquarium...
, took DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
samples from the population of dolphins off the coast of Townsville, Queensland
Townsville, Queensland
Townsville is a city on the north-eastern coast of Australia, in the state of Queensland. Adjacent to the central section of the Great Barrier Reef, it is in the dry tropics region of Queensland. Townsville is Australia's largest urban centre north of the Sunshine Coast, with a 2006 census...
, and sent them to the National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
's Southwest Fisheries Science Center in La Jolla, California. The results showed George Heinsohn was correct in his hypothesis that the Townsville population was a new species.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
QM
Queensland Museum
The Queensland Museum is the state museum of Queensland. The museum currently operates four separate campuses; at South Brisbane, Ipswich, Toowoomba and Townsville.The museum is funded by the State Government of Queensland.-History:...
JM4721 (JUCU MM61) is the skull and some other bones of an adult male found drowned in a shark net at Horseshoe Bay
Horseshoe Bay, Queensland
Horseshoe Bay is a village on Magnetic Island, Queensland, Australia. It is considered the tourist strip of the island. From September 2006, Horseshoe Bay was undergoing a string of housing development behind the existing residential area to the southern part of the bay. It is also a major...
, Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, on 21 April 1972. It was about 11 years old at the time of its death.
Description
A species of delphinid in a genus, Orcaella, which contains one other species, the Irrawaddy dolphinIrrawaddy dolphin
The Irrawaddy dolphin is a euryhaline species of oceanic dolphin found in discontinuous subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia.-Etymology and taxonomic history:...
Orcaella brevirostris, O. heinsohni is subtly tri-coloured: brownish on the top, lighter brown along the sides, and a white belly; the Irrawaddy dolphin, on the other hand, is uniformly slate grey except for the white belly. The new species has a rounded forehead, very unlike other dolphin species in Australia, and the very small, "snubby" dorsal fin distinguishes it from other dolphins in its range. The lack of a groove on each side of the back and the presence of a neck crease further distinguishes this species from its relative.
Range and status
In the Pacific OceanPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
off Townsville, about 200 individual snubfin dolphins were found. The range of the species is expected to extend to Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
; that is, O. heinsohni is endemic to the northern half of the Sahul Shelf
Sahul Shelf
The Sahul Shelf is part of the continental shelf of Sahul and lies off the coast of Australia. The Sahul Shelf proper stretches northwest from Australia much of the way under the Timor Sea towards Timor, ending where the seabed begins descending into the Timor Trough...
, but that the majority live in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n waters. They are not thought to be common, and are being given a high conservation
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
priority. Its IUCN classification of "data deficient" refers to this species and the Irrawaddy dolphin combined (Cetacean Specialist Group 1996). Threats include drowning in fishery and antishark nets; while some hunting by indigenous people probably occurs (as evidenced by the 1948 specimen), this is likely to be insignificant compared to the threat posed by drowning.
Conservation
The Australian snubfin dolphin is 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...
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. In addition, Australian snubfin dolphin is covered by Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).
External links
- http://media.jcu.edu.au/story.cfm?id=425
- DNA samples reveal new dolphin species
- Rare Australian snubfin dolphins filmed for first time
- Great Barrier Reef Marine Park Authority enraged at death of snubfin dolphins tied to concrete block
- Convention on Migratory Species page on the Australian snubfin dolphin
- Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region