Sonic Tags (Underwater Sonic transmitters) make it possible to have a better understanding of movements of individual animals on an ongoing basis.

An underwater receiver, or a series of receivers, can be located at strategic locations along the reef slope. They will record when a tagged animal is within a certain distance from the receiver. This signal is constant as long as the animal remains within the reach of the transmitter. Once the animal moves beyond the transmission distance the signal will cease. (See diagram on the right)

Similar transmitters are currently being used in the Coral Sea as part of a home range study of reef sharks at Osprey Reef.

At Lady Elliot Island, sonic transmitters be attached to three manta rays. the range will be somewhere between 500 and 1000 metres

Size of the transmitter is 48mm long x 16mm diameter. The tags will be delivered via a hand spear apparatus by divers on scuba gear, and the tags will be inserted in the fleshy area on the back of the animal. Similar methodology has been used for tagging white pointer sharks in the Spencer Gulf area of South Australia.

It is expected that apart from the initial 'fright' of being jabbed with the tag, disturbance to the animals will be minimal. Field work for this part of the project was undertaken in early May 2001.