Dugong behaviour and the effects of boats and pingers (C1.4.3.1S)

Task leader: Ms Amanda Hodgson, CRC Reef and James Cook University.

Task associate: Dr Kirsten Dobbs, Great Barrier Reef Marine PArk Authority.

Dugong and calf seen from the blimp-cam. Photo by Amanda Hodgson

My project is aimed at determining the effects of anthropogenic, or human produced, noise on the behaviour of dugongs Dugong dugon. The objectives of this project are to find out whether boat noise and pingers adversely effect dugong behaviour and could alienate them from their required inshore habitat areas.

During my project I have developed a new method for observing dugongs using the blimp-cam. This consists of a helium-filled balloon (blimp) with a mounted video camera. Controls for the camera and a monitor showing the view from the blimp-cam are on board the boat. Using this system I have been able to record previously unobtainable information about dugong behaviour including daily behaviour patterns, herd movements, structure and composition, social behaviour, mother and calf relationships and surfacing behaviour.From this I will be able to determine what environmental factors effect dugong behaviour and suggest why dugongs in Moreton Bay form large herds.

I conducted a number of controlled experiments to determine whether anthropogenic noise sources effect dugong behaviour. The two noise sources considered were boats and pingers (acoustic alarms used on fishing nets to reduce marine mammal entanglements). From the boat pass experiments as well as through observing the response of dugongs to independent boats passing opportunistically I have been able to compare the risk of boat strikes and boat disturbance to dugongs.