Snubfin dolphin in a class of its own

An Australian snubfin dolphin - not a variety of Irrawaddy dolphin but a separate species, named for its stubby dorsal fin.

SYDNEY - A new species of dolphin has been found living in the warm tropical waters of northern Australia.

Scientists had always thought the dolphins were a local variation of the Irrawaddy dolphin, a species which ranges into Southeast Asia.

But marine biologists have found enough differences in the population to declare it a separate species, the Australian snubfin dolphin.

It derives its name from its short, stubby dorsal fin.

Identifying a new species is a rare event in the cetacean world and researchers from James Cook University and the Museum of Tropical Queensland, both in Townsville, are celebrating the find.

"There are clear differences between the two populations that had not been previously recognised and these were confirmed by the studies on DNA," said Isabel Beasley, a PhD student and research team member.

The dolphins, mostly found in shallow coastal waters, are susceptible to being caught in fishing and anti-shark nets. Coastal development may also affect their health.

Scientists have no idea how numerous they are - around 200 are believed to live in the ocean off Townsville, northern Queensland, and there is an unknown number living in the rest of the species' range, which extends to Western Australia.

"Even though Australia is a developed country ... more is known about the Mekong River dolphin population in Cambodia than the Australian species," said Peter Arnold, of the Museum of Tropical Queensland.

They have been given the Latin name orcaella heinsohni, after George Heinsohn, a researcher who studied dolphins in the 1970s.