Researchers from the University of Queensland, the University of Western Australia and the Florida Atlantic University have teamed up with Cairns Marine to investigate the feeding behaviours of endangered freshwater sawfish. Sawfish were once common along the east coast of Australia, but are now restricted to remote coastal and freshwater habitats of Far North Queensland.
The body shape of sawfish combines a shark-like tail with an elongated saw that bears lateral teeth that grow continuously. Throughout popular and scientific literature, it has become an established fact that sawfish use their saw during feeding, and a variety of uses are proposed. However, to date only one individual of an Atlantic sawfish species has been studied for its prey capture mechanisms for two weeks.
Therefore, this study investigates how freshwater sawfish capture and manipulate their prey, using a variety of methods. Sawfish captured from their natural habitat are transported back to the holding facilities of Cairns Marine. When the animals start to feed, feeding events are recorded and later analysed, with the aim to compile an ethogram – a catalogue of behaviours displayed by freshwater sawfish.
Stimuli simulating different aspects of prey are presented to the sawfish, to investigate which behaviours they evoke. For example, sharks and rays are known to use electroreception during foraging. This sense is visible as minute pores in the skin on the head of the animals, and allows them to detect electric fields as weak as a few Nanovolt per centimetre. Such weak fields occur naturally, created by the ion transport over the gill membranes of fish.
The information collected in this project will increase our knowledge of sawfish behaviours and may be used during future captive breeding studies.