Biology & Behaviour
Learn about snubfin dolphins, how they were discovered, where they live, threats and more
The Australian snubfin dolphin (Orcaella heinsohni) is a coastal dolphin species in the family Delphinidae, within the genus Orcaella. The other species within the genus is the Irrawaddy dolphin (O. brevirostris). The closest relative to Orcaella is the killer whale Orcinus orca.
Irrawaddy dolphins were initially thought to occur in Australian waters and were first recorded in 1964 when anthropologists found two Australian snubfin dolphin skulls that had been eaten by Indigenous people in Arnhem Land in 1948.
In the mid-1990s, Dr Isabel Beasley, Snubfin Dolphin Conservation Project Director, began to suspect that Irrawaddy dolphins in Australia were a different species to those found in Southeast Asia. Dr Beasley travelled the world to measure all the skulls she could find to determine if differences existed through skull measures and collection of genetic samples.
In 2000, Dr Beasley met Dr Peter Arnold from the Museum of Tropical Queensland, Townsville, who in a remarkable coincidence had discovered similar differences through his work on Irrawaddy dolphins from the Townsville region. The two researchers teamed up and narrowed down the specific difference, which led Dr. Beasley to re travel around the world to measure further skulls and collect additional samples. In 2005, a description of the Australian snubfin dolphin was published in Marine Mammal Science, a discovery that took 10 years of research to confirm.
In 2005, a description of the Australian snubfin dolphin was published in Marine Mammal Science, a discovery that took 10 years of research to confirm.
The name ‘snubfin dolphin’ was first suggested in 1981, as an alternative common name. This name highlights a diagnostic external character, is appropriate to all populations, and has previously been included in general field guides. The common name, the Australian snubfin dolphin, reflects that the majority of known specimens and morphological work are based on Australian populations.
The species was named for George Heinsohn, a James Cook University researcher, recognising his pioneering work on northeastern Australian odontocetes, including Australian snubfin dolphin specimens.
The Australian snubfin dolphin resembles the Irrawaddy dolphin in appearance, however, there are clear and consistent differences in coloration, cranial and external morphometrics, postcranial morphology and molecular data between the two species.
The Australian snubfin dolphin resembles the Irrawaddy dolphin in appearance, however, there are clear and consistent differences.
Total length reaches 230cm in females and 270cm in males. Mass of three adults (2.14-2.25m long) was recorded as 114-133kg. The head is rounded in lateral view and lacks a rostrum. The body has a subtle three-tone color pattern; a distinct dark brown dorsal cape, light brown lateral field, and white abdominal field. The small variably shaped dorsal fin (from rounded to slightly falcate) is situated in the latter half of the body. The flippers are broad, paddle-like and highly mobile. There are 11-22 teeth in each half of the upper jaw and 14-19 teeth in each lower jaw.
Orcaella skin samples from the Kikori Delta of southern Papua New Guinea were compared to other Orcaella samples from Australia and Asia using mtDNA. Phylogenetic reconstruction showed that the Papua New Guinea samples clustered with Australian samples, confirming that the Australian snubfin dolphin also occurs in southern Papua New Guinea waters.
The Australian snubfin dolphin is found throughout northern Australia and Gulf Province, southern Papua New Guinea. In Australia, the species primary range stretches from Roebuck Bay, Western Australia, northeast through the Northern Territory and south along the Queensland coast to the Fitzroy River region, Central Queensland. Extralimital records extend south as far as Brisbane, Queensland, and the species is occasionally recorded south of Roebuck Bay to the North West Cape in Western Australia. In Papua New Guinea, the species in only known from the Kikori Delta region, southern Papua New Guinea.
The Australian snubfin dolphin is found throughout northern Australia and Gulf Province, southern Papua New Guinea.
The Australian snubfin dolphin occurs over the Sahul Shelf of Australia/Papua New Guinea, whereas the Irrawaddy dolphin occurs over the Sunda Shelf of South and Southeast Asia. These shelves are separated by deep oceanic waters that remained separate even during periods of lowered sea levels in the Pleistocene Ice Ages.
There are no national abundance estimates for Australian snubfin dolphins in Australia or Papua New Guinea. As of 2010, only three abundance estimates were available: 1,000 animals along the Western Gulf of Carpentaria, Northern Territory, 64-76 individuals in Cleveland Bay, North Queensland and 71-80 individuals from the Keppel Bay region, Central Queensland.
More recent studies have estimated 136-222 individuals in Port Essington, and 19-70 individuals in the Darwin region (Northern Territory); 133 individuals in Roebuck Bay and 48-54 individuals in Cygnet Bay (Western Australia); and, 150 individuals in Cleveland Bay (Queensland). Available information suggests that Australian snubfin dolphins are found in small populations of 200 individuals or less, with evidence of high site fidelity and a lack of movement between sites.
Sighting records indicate that Australian snubfin dolphins occur mainly in shallow (<20m deep), coastal habitats, with the highest frequency of sightings adjacent to river and tidal creek mouths and in sheltered, mangrove-lined bays. They have been reported utilising channel habitats, including dredged channels in some locations.
Diet data are limited, but the species has been described as an opportunistic generalist feeder, preying upon bottom-dwelling and pelagic fish and cephalopods associated with coastal and estuarine waters. Australian snubfin dolphins, along with Irrawaddy dolphins, are occasionally observed spitting jets of water into the air. While this behaviour has not been systematically investigated, it is most commonly associated with feeding behaviour.
Diet data are limited, but the species has been described as an opportunistic generalist feeder, preying upon bottom-dwelling and pelagic fish and cephalopods associated with coastal and estuarine waters.
Shark bite scars, which are indicative of failed predation attempts, have been observed on Australian snubfin dolphins throughout their range. Studies in Western Australia suggest that shark predation risk represents an important ecological pressure.
Interactions between Australian snubfin dolphins and Australian humpback dolphins (Sousa sahulensis) occur occasionally, with both aggressive/sexual (humpbacks dominating) and amicable foraging/traveling behaviour observed. A hybrid, confirmed by molecular analyses as originating from a snubfin mother and humpback father, was documented at Cygnet Bay by Murdoch University researchers.
Very little is known about the life history of the Australian snubfin dolphin. Age was determined for 18 snubfin dolphins from Townsville waters, where it was estimated that Australian snubfin dolphins may live for at least 30 years. Gestation length has been estimated as 11 months based on known rates of other similar species.
Australian snubfin dolphins may live for at least 30 years.
There is no information on age at sexual maturity of the Australian snubfin dolphin. However, based on the Irrawaddy dolphin, age of first reproduction has been estimated as nine years and generation length estimated as 15.6 years, based on an ‘age at first reproduction’ of nine years old, and ‘oldest age of a reproducing female’ as 28 years. Reproductive seasonality of the Australian snubfin dolphin is unknown.
The Australian snubfin dolphin is listed as ‘Migratory’ by the Australian Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), ‘Vulnerable’ by the IUCN Red List of Threatened Species, and listed as ‘Appendix I’ by the Convention on International Trade in Endangered Species.
The Australian snubfin dolphin is listed as ‘Vulnerable’ by the IUCN Red List of Threatened Species.
Previously, the major known threat to the species in Australia was accidental capture in nets used for bather protection by the Queensland Shark Control Program. A gradual gear change from nets to baited hook drum-lines may have assisted to reduce mortalities. Alternatively, local extirpation may have occurred from the high levels of historical bycatch in these nets.
Currently, near-shore and commercial fisheries are a threat in both northern Australia and southern Papua New Guinea. Large-mesh gill-nets are set in creeks, rivers, estuaries and headlands, which are considered some of the preferred habitats of the Australian snubfin dolphin. The historical and current magnitude of Australian snubfin dolphin bycatch in fisheries remains unknown, however recent studies in Papua New Guinea have confirmed alarming levels of mortality in subsistence fisheries.
Habitat loss and degradation caused by increased development and human population growth is a concern throughout the species range. Suggested effects include:
Elevated levels of anthropogenic contaminants have been observed in the tissue of snubfin dolphins in central Queensland. A lack of data on population sizes, trends or habitat use precludes adequate consideration of the Australian snubfin data (and other coastal species) within environmental impact assessments. Similarly, a lack of empirical studies on the impacts of potential threats, particularly a lack of baseline data prior to threatening activities taking place, hinders an understanding of the effects of anthropogenic impacts on small, localised populations.
No direct catch for Australian snubfin dolphins is known, although there are reports that the species was historically hunted by some Indigenous communities in Australia. Two snubfin dolphins were kept in captivity in Cairns in the late 1960s. These dolphins were collected north of Cairns in 1969 and are now deceased. Live capture of cetaceans is no longer permitted under Australian law, and not permitted in Papua New Guinea.
More research is needed throughout the range of the Australian snubfin dolphin in northern Australia and southern Papua New Guinea in order to understand population status, threats and develop effective management decisions to ensure effective conservation of the species.
Allen, S.J., Cagnazzi, D.D., Hodgson, A.J., Loneragan, N.R., and Bejder, L. (2012). Tropical inshore dolphins of north-western Australia: Unknown populations in a rapidly changing region. Pacific Conservation Biology 18: 56-63.
Beasley, I., Roberston, K.M., and Arnold, P. (2005). Description of a new dolphin, the Australian snubfin dolphin Orcaella heinsohni sp. n. (Cetacea, Delphinidae). Marine Mammal Science 21: 365-400.
Berg Soto, A., H. Marsh, Y. Everingham, J. N. Smith, G. J. Parra, and M. Noad. 2014. Discriminating between the vocalizations of Indo-Pacific humpback and Australian snubfin dolphins in Queensland, Australia. The Journal of the Acoustical Society of America 136: 930-938.
Brown, A.M., Bejder, L., Pollock, K.H., and Allen, S.J. (2016). Site-specific assessments of the abundance of three inshore dolphin species to inform conservation and management Frontiers in Marine Science 3: 4.
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Cagnazzi, D., Parra, G.J., Westley, S. and Harrison, P.L. (2013). At the Heart of the Industrial Boom: Australian Snubfin Dolphins in the Capricorn Coast, Queensland, Need Urgent Conservation Action. PLoS ONE 8: e56729..
Minton, G., Smith, B.D., Braulik, G.T., Kreb, D., Sutaria, D. & Reeves, R. 2017. Orcaella brevirostris (errata version published in 2018). The IUCN Red List of Threatened Species 2017: e.T15419A123790805. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T15419A50367860.en. Downloaded on 22 March 2019.
Parra, G., Cagnazzi, D. & Beasley, I. 2017. Orcaella heinsohni (errata version published in 2018). The IUCN Red List of Threatened Species 2017: e.T136315A123793740. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T136315A50385982.en. Downloaded on 22 March 2019.
Parra, G. J., P. J. Corkeron, and H. Marsh. 2006. Population sizes, site fidelity and residence patterns of Australian snubfin and Indo-Pacific humpback dolphins: Implications for conservation. Biological Conservation 129: 167–180.
Parra, G.J. and Jedensjö, M. (2014). Stomach contents of Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback dolphins (Sousa chinensis). Marine Mammal Science 30: 1184-1198. doi:10.1111/mms.12088