Study Description

This study aims to determine the diet and movement of Port Jackson sharks (Heterodontus portusjacksoni) and southern eagle rays (Myliobatis tenuicaudatus) in metropolitan South Australia.

 

Port Jackson sharks are a small, benthic shark species, commonly found resting under rockledges and in seagrass beds. Females are around 1 m at maturity and males smaller, at around 75 cm. Known for their distinctive jaws and teeth, this species commonly feeds on benthic invertebrates and molluscs. Studies have shown large scale migrations for these species along the east coast, but we’re not sure if they undertake large scale movements in South Australia.

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Southern eagle rays are another commonly spotted species around South Australia. Easily recognisable by their triangular shaped wings and large head, this is another species that likes to feed on benthic invertebrates and molluscs. They can reach 1.6 m wide, with the males again smaller than the females. They have been found to move away from the coast during winter in other areas such as Coffin Bay, but their movements along metropolitan Adelaide is still misunderstood.

 

The overall objective of this study is to determine the movement and diet of these species. We will determine their site fidelity and range, their general diet, the competition between them, and how this all varies throughout seasons and with exposure to urbanisation.

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We will be using biochemical analyses to examine diet, and acoustic telemetry to determine the movements and space use. Acoustic telemetry works by inserting a transmitter into the animal, which will send a signal to a receiver when the animal swims close by. We have receivers covering the whole coastline of Adelaide.