Dolphins

Australian Humpback dolphin and Bottlenose dolphin.

Photo credit: © Amanda Delaforce

Nine species of dolphin have been recorded in the Great Sandy Marine Park. Dolphin species are either ‘resident’ dolphins that spend much of their lifetime in the park, or ‘transient’ dolphins that temporarily visit the marine park. Only two species are considered resident in the marine park: the Australian humpback dolphin and the Indo-Pacific (inshore) bottlenose dolphin.

Dolphin species found in the Great Sandy Marine Park include:

• Australian humpback dolphin (Sousa sahulensis)
• Indo-Pacific (inshore) bottlenose dolphin (Tursiops aduncus)
• Common dolphin (Delphinus delphis)
• Bottlenose dolphin (Tursiops truncatus)
• Risso’s dolphin (Grampus griseus)
• Spotted dolphin (Stenella attenuate)
• Striped dolphin (Stenella coeruleoalba)
• Fraser’s dolphin (Lagenodelphis hosei)
• Rough-toothed dolphin (Steno bredanensis)

Although all dolphins in Australian waters are protected, only the Australian humpback dolphin is listed as a threatened species (‘vulnerable’) under the Nature Conservation Act 1992, owing to the existence of small, discrete populations, two of which are in the Great Sandy Strait. These two small socially-isolated communities of Australian humpback dolphins are separated by the shallow area in the centre of the Straits near Sheridan Flats. It is estimated that each community contains approximately 75 individuals¹. This species shows a preference for areas in proximity to sandbanks, rocky reefs, estuaries and intertidal beaches.

Indo-Pacific bottlenose dolphins are considerably smaller than common bottlenose dolphins and occur in tropical-temperate inshore waters of the Indo-Pacific Region. In the marine park, they are commonly found in the shallower waters of Hervey Bay and the northern Great Sandy Strait. This species of dolphin is often seen riding the bow wave of boats, playing in the waves and launching themselves out of the water. The offshore waters adjacent to K’gari (Fraser Island) are thought to support Australia’s only known resident population of Risso’s dolphin (Grampus griseus). This species lives in large groups containing hundreds of individuals in deep offshore waters but has been known to strand in shallow waters. Risso’s dolphins are often observed in association with other oceanic cetaceans, in particular short-finned pilot whales.

• Read more about other dolphins.

References

¹ Cagnazzi D, Harrison P, Ross G 2011, ‘Abundance and site fidelity of Indo-Pacific Humpback dolphins in the Great Sandy Strait, Queensland, Australia,’ Marine Mammal Science, vol. 27, no. 2, pp. 255-281.

² Corkeron, PJ, & Bryden MM 1992, ‘Sightings of Risso's Dolphin, Grampus griseus (Cetacea: Delphinidae), off Fraser Island, Queensland’, Australian Mammalogy, vol. 15, pp.129-130.