Aerial survey methodology has been detailed by Marsh and Sinclair (1989 a and b) and Marsh and Saalfeld (1989 a). The transect width (200 m on either side of the aircraft at survey altitude) was demarcated with fibre glass rods attached to artificial wing struts on either side of the aircraft. Each sighting was recorded as being made in the upper, middle or bottom third of the transect to facilitate deciding whether simultaneous sightings by tandem observers were of the same group of animals. Transects were flown in an east-west direction and usually extended 21.6 km from the coast and/or offshore islands except between Hinchinbrook Island and the mainland where mountains made east- west flying dangerous. Transects were spaced 5’ latitude apart, except where sampling intensity was increased due to the presence of large seagrass beds. The design of the survey was exactly the same as that used in 1992 except that: (1) the area north of Dunk Island was excluded as there were too few dugongs to make a population estimate in either of the previous two surveys, and (2) extra transects were added in the Shoalwater Bay and Port Clinton area due to the known high density of dugongs in those bays.

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).