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Ecology, management and conservation in natural and modified habitats
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RESEARCH ARTICLE
Contents Vol 33(3)

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

Abstract

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.


Acknowledgments

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.


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