Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats

Summer survey of dugong distribution and abundance in Shark Bay reveals additional key habitat area

David K. Holley A B E , Ivan R. Lawler C and Nicholas J. Gales D
+ Author Affiliations
- Author Affiliations

A Department of Conservation and Land Management, Locked Bag 104, Bentley Delivery Centre, Bentley, WA 6983, Australia.

B School of Natural Sciences, Edith Cowan University, Joondalup, WA 6027, Australia.

C School of Tropical Environment Studies and Geography, James Cook University, Townsville, Qld 4811, Australia.

D Australian Antarctic Division, Channel Highway, Kingston, Tas. 7050, Australia.

E Present address: Department of Fisheries Western Australia, 39 Northside Drive, Hillarys, WA 6025, Australia.

Wildlife Research 33(3) 243-250 https://doi.org/10.1071/WR05031
Submitted: 22 March 2005  Accepted: 4 May 2006   Published: 31 May 2006


The first standardised summer aerial survey of dugongs within Shark Bay in Western Australia, and the fourth in a series of surveys of this area, was undertaken during February 2002. This survey returned a population estimate of 11 021 ± 1357 (s.e.), a result similar to the first two winter surveys in 1989 and 1994 but considerably lower than the 1999 survey. Distribution was markedly different in this survey compared with all previous surveys, which were conducted during winter, confirming that dugongs within Shark Bay undertake a seasonal migration driven by changes in sea surface temperature. In addition to this distribution pattern it was identified that 24% of the population during summer occurred within an area known as Henri Freycinet Harbour. That is, while dugongs have been reported in this south-western region of the bay previously in summer, this is the first time that the substantial size (2629 ± 780, s.e.) of the summer dugong population has been quantified. Differences in the population estimate between the 1999 survey and this survey may be explained through large-scale movement patterns of dugongs between Shark Bay and Ningaloo Reef and Exmouth Gulf to the north, patterns that should be considered in the management of dugongs for the entire region.


The authors thank observers Richard Campbell, Gail Nolan-Neylan and Judy Davidson for their dedication to this survey. We also thank Eddie Malatesta for unwavering piloting in extreme conditions as well as Rupert Davies and CALM (Shark Bay District) for logistical support, and CALM (Marine Conservation Branch), and the Yadgalah Aboriginal Corporation Inc. for direction. Funding was provided through a Commonwealth World Heritage grant.


Anderson, P. K. (1982). Studies of dugongs at Shark Bay, Western Australia. I. Analysis of population size, composition and habitat use on the basis of aerial survey. Australian Wildlife Research 9, 69–84.
CrossRef |

Anderson, P. K. (1986). Dugongs of Shark Bay, Australia – seasonal migration, water temperature and forage. National Geographic Research 2, 473–490.

Anderson, P. K. (1998). Shark Bay dugongs (Dugong dugon) in summer. II: Foragers in a Halodule-dominated community. Mammalia 62, 409–425.

Bancroft K. P., and Davidson J. A. (2002). Field survey of marine ecological communities in Shark Bay Marine Park and Hamelin Pool Marine Nature Reserve (18–29 March 2002). Marine Conservation Branch, Department of Conservation and Land Management. Perth.

Bayliss, P. (1986). Factors affecting aerial surveys of marine fauna, and their relationship to a census of dugongs in the coastal waters of northern Australia. Australian Wildlife Research 13, 27–37.
CrossRef |

Bayliss, P. , and Freeland, W. J. (1989). Seasonal distribution and abundance of dugongs in the Western Gulf of Carpentaria. Australian Wildlife Research 16, 141–149.
CrossRef |

Bruce E. (1987). Application of spatial analysis to coastal and marine management in the Shark Bay World Heritage Area, Western Australia. Ph.D. Thesis, University of Western Australia, Perth.

Caughley, G. , and Grigg, G. C. (1981). Surveys of the distribution and density of kangaroos in the pastoral zone of South Australia, and their bearing on the feasibility of aerial surveys in large and remote areas. Australian Wildlife Research 8, 1–11.
CrossRef |

CALM (1996). Shark Bay Marine Reserves Management Plan 1996–2006. Management Plan No. 34. Department of Conservation and Land Management for the National Parks and Nature Conservation Agency. Perth.

Heinsohn, R. , Lacy, R. C. , Lindenmayer, D. B. , Marsh, H. , Kwan, D. K. , and Lawler, I. R. (2004). Unsustainable harvest of dugongs in Torres Strait and Cape York (Australia) waters: two case studies using population viability analysis. Animal Conservation 7, 417–425.
CrossRef |

Jolly, G. M. (1969). Sampling methods for aerial censuses of wildlife populations. East African Forestry Journal 34, 46–49.

Gales, N. , McCauley, R. , Lanyon, J. , and Holley, D. K. (2004). Change in abundance of dugongs in Shark Bay, Ningaloo and Exmouth Gulf, Western Australia: evidence for large-scale migration. Australian Wildlife Research 31, 283–290.
CrossRef |

Loneragan N. R., Kenyon R. A., Crocos P. J., Ward R. D., Lehnert S., Haywood M. D. E., Arnold S., Barnard R., Burford M., Caputi N., Kangas M., Manson F., McCulloch R., Penn J. W., Sellars M., Grewe P., Ye Y., Harch B., Bravington M., and Toscas P. (2003). Developing techniques for enhancing prawn fisheries, with a focus on brown tiger prawns (Panaeus esculentus) in Exmouth Gulf. Final Report on FRDC Project 1999/222. CSIRO, Cleveland.

Logan, B. W. , Read, J. F. , and Davies, G. R. (1970). History of carbonate sedimentation Quaternary Epoch, Shark Bay. American Association of Petroleum Geologist Memoir 13, 38–84.

Lanyon, J. M. (2003). Distribution and abundance of dugongs in Moreton Bay, Queensland Australian Wildlife Research 30, 397–409.
CrossRef |

Marsh H., and Lawler I. R. (2001). Dugong distribution and abundance in the southern Great Barrier Reef Marine Park and Hervey Bay: results of an aerial survey in October–December 1999. Report to Great Barrier Reef Marine Park Authority. Townsville, Qld.

Marsh H., and Lawler I. R. (2002). Dugong distribution and abundance in the northern Great Barrier Reef Marine Park. November 2000. Report to the Great Barrier Reef Marine Park Authority. Townsville, Qld.

Marsh H., and Lawler I. R. (2004). Review and refinement of the most appropriate and cost effective method and priorities for determining dugong population numbers and distribution in Queensland and the Torres Strait. Report to Great Barrier Reef Marine Park Authority and the Australian Fish Management Authority. Townsville, Qld.

Marsh, H. , and Saalfeld, W. K. (1989). Distribution and abundance of dugongs in the northern Great Barrier Reef Marine Park. Australian Wildlife Research 16, 429–440.
CrossRef |

Marsh, H. , and Saalfeld, W. K. (1990). The distribution and abundance of dugongs in the Great Barrier Reef Marine Park south of Cape Bedford. Australian Wildlife Research 17, 511–524.
CrossRef |

Marsh H., and Saalfeld W. K. (1991). The status of the dugong in Torres Strait. In ‘Sustainable Development of Traditional Inhabitants of the Torres Strait Region’. (Eds D. Lawrence and T. Cransfield-Smith.) pp. 187–194. Great Barrier Reef Marine Park Authority Workshop Series No. 10.

Marsh, H. , and Sinclair, D. F. (1989). Correcting for visibility bias in strip transect aerial surveys of aquatic fauna. Journal of Wildlife Management 53, 1017–1024.

Marsh, H. , Prince, R. I. T. , Saalfeld, W. K. , and Shepherd, R. (1994). The distribution and abundance of the dugong in Shark Bay, Western Australia. Australian Wildlife Research 21, 149–161.
CrossRef |

Marsh, H. , Lawler, I. R. , Kwan, D. K. , Delean, S. , Pollock, K. H. , and Alldredge, M. (2004). Aerial surveys and the potential biological removal technique indicate that the Torres Strait dugong fishery is unsustainable. Animal Conservation 7, 435–443.
CrossRef |

Pearce, A. F. , Prata, A. J. , and Manning, C. R. (1989). Comparison of NOAA/AVHRR-2 sea-surface temperatures with surface measurements in coastal waters. International Journal of Remote Sensing 10, 37–52.

Preen A. R. (1989). Dugongs. Volume 1. The status and conservation of dugongs in the Arabian Region. Report to Meteorological and Environmental Protection Administration, Ministry of Defence and Aviation, Kingdom of Saudi Arabia.

Preen, A. , and Marsh, H. (1995). Response of dugongs to large-scale loss of seagrass from Hervey Bay, Queensland, Australia. Australian Wildlife Research 22, 507–519.
CrossRef |

Preen, A. R. , Marsh, H. , Lawler, I. R. , Prince, R. I. T. , and Shepherd, R. (1997). Distribution and abundance of dugongs, turtles, dolphins and other megafauna in Shark Bay, Ningaloo Reef and Exmouth Gulf, Western Australia. Australian Wildlife Research 24, 185–208.
CrossRef |

Prince R. I. T. (2001). Aerial survey of the distribution and abundance of dugongs and associated macrovertebrate fauna – Pilbara coastal and offshore region, WA. Completion Report to Environment Australia. Department of Conservation and Land Management, Perth.

Prince R. I. T., Anderson P. K., and Blackman D. (1981). Status and distribution of dugongs in Western Australia. In ‘The Dugong: Proceedings of a Seminar/Workshop held at James Cook University, 8–13 May 1979’. (Ed. H. Marsh.) pp. 67–87. (James Cook University: Townsville, Qld.)

Sheppard, J. K. , Preen, A. R. , Marsh, H. , Lawler, I. R. , Whiting, S. D. , and Jones, R. E. (2006). Movement heterogeneity of dugongs, Dugong dugon (Müller) over large spatial scales. Journal of Experimental Marine Biology and Ecology ,in press

Stokes T. (2004). Report of a workshop on future aerial surveys for dugongs in Queensland and the Torres Strait. CRC Reef, Townsville, Qld.

Walker, D. I. , Kendrick, G. A. , and McComb, A. J. (1988). The distribution of seagrass species in Shark Bay, Western Australia, with notes on their ecology. Aquatic Botany 30, 305–317.
CrossRef |

Walker D. I. (1989). Seagrass in Shark Bay – the foundations of an ecosystem. In ‘Seagrasses: A Treatise on Seagrass With Special Reference to the Australian Region’. (Eds A. W. D. Larkum, A. J. McComb and S. A. Shepherd.) pp. 182–210. (Elsevier: Amsterdam.)

Rent Article (via Deepdyve) Export Citation Cited By (9)