Juvenile white sharks Carcharodon carcharias use estuarine environments in south-eastern Australia

Estuarine environments are known to provide important feeding, breeding, resting and nursery areas for a range of shark species, including some which are considered dangerous to humans. Juvenile white sharks (<3 m) are known to frequent inshore environments, particularly ocean beaches, but their presence in and use of estuaries and coastal embayments is unclear. Given that estuarine environments are often surrounded by highly populated areas, understanding how white sharks use these environments will not only assist with their conservation management, but also inform public safety policies. The use of estuarine environments by acoustic-tagged white sharks was investigated from 2009 to 2015 at Port Stephens, New South Wales and Corner Inlet, Victoria, both of which adjoin known nursery areas for the species. Juvenile white sharks were detected within both estuaries, with 20 individuals recorded within the Port Stephens estuary, including four on one day. Only one tagged shark was detected within Corner Inlet; however, monitoring effort and local tagging in the area was more restricted. Detections in Port Stephens were predominantly from October to January and peaked in November. This study demonstrates that the footprint of known nursery areas for white sharks in eastern Australia should be expanded to include their adjacent estuarine environments. Consequently, there is clear potential for them to be exposed to a range of anthropogenic estuarine impacts, and that human interactions are more likely over warmer periods (summer), when human use of such waterways is more prevalent.

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