In 1985, dugongs were censused from the air at an overall sampling intensity of 10.9% over an area of 5480 km2 within the inshore areas of the northern third of the Central Section of the Great Barrier Reef Marine Park and adjacent waters of Queensland, and at an overall intensity of 10.7% over a corresponding area of 15091 km2 in the Capricorn Section of the Park. Sightings were corrected for perceptual bias (the proportion of animals visible in the transect which were missed by observers), and availability bias (the proportion of animals that were invisible due to water turbidity) using survey-specific correction factors. The resultant population estimate for the northern half of the Central Section was 1024 ± 192 dugongs at an overall density of 0.19 ± 0.04 km-2, a precision of 19%. The population estimate for the Capricorn Section was 2144 ± 428 dugongs at an overall density of 0.14 ± 0.03 km-2, a precision of 20%. The highest densities of animals were seen on coastal seagrass beds in water depths of less than 5 m. Maps of density and distribution are given.

Please contact Helene Marsh Helene.Marsh@jcu.edu.au for GIS data. Funding for these surveys was obtained from the following government agencies: - Great Barrier Reef Marine Park Authority (GBRMPA), - Department of Environment and Resource Management (DERM), - Australian Marine Mammal Centre (AMMC), - Torres Strait Regional Authority (TSRA), - Australian Fisheries Management Authority (AFMA), - Marine and Tropical Sciences Research Facility (MTSRF), - National Environmental Research Program (NERP).