Australian snubfin dolphin

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 has three, while the Irrawaddy dolphin only has two colours on its skin. The skull and the fins also show minor differences between the two species.

A species of delphinid in a genus, Orcaella, which contains one other species, the Irrawaddy dolphin Orcaella brevirostris, O. heinsohni is subtly tricoloured: 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.

Australian snubfin dolphin
  • Size

    The maximum recorded length for males is 2.70 m and 2.30 m for females. The maximum weight is 133 kg. There appears to be some sexual dimorphism in Australian Snubfin Dolphins, with males growing larger than females, but further specimens are required for examination before this can be verified.

  • Feeding

    Australian Snubfin Dolphin prey includes fish of the families Engraulidae, Clupeidae, Chirocentridae, Anguillidae, Hemirhampidae, Leiognathidae, Apogonidae, Pomadasydae, Terapontidae and Sillaginidae. These fishes are typically associated with shallow coastal waters and estuaries in tropical regions.

  • Life History

    The age at sexual maturity for Australian Snubfin Dolphins is unknown. The length at sexual maturity is about 2 m . Australian Snubfin Dolphins may reach an age of 28 years. Limited data is available for the Australian Snubfin Dolphin, resulting in reproductive parameters being estimated from the closely related Irrawaddy Dolphin. The Irrawaddy Dolphin's mating season is from March to June (at 11°–12° N), and April to June (at 0°–1° S). However, Australian Snubfin Dolphins have been observed socialising year round in Cleveland Bay, suggesting that Australian Snubfin Dolphins may mate year round. Gestation for Irrawaddy Dolphins lasts 14 months (captive animal) and calves are born in August or September.

  • Behavior

    Boat-based surveys along the east coast of Queensland indicate that Australian Snubfin Dolphins are primarily found in shallow waters less than 20 m deep, close to the coast, close to river and creek mouths and in the proximity of seagrass beds. Within Cleveland Bay, north-east Queensland, Australian Snubfin Dolphins tend to concentrate their activities in areas with these specific features. Within such areas, animals spend most of their time foraging and travelling, and to a lesser extent socialising. The predominance of foraging activities in these areas indicate that these areas represent important feeding habitats for these species..