Bull sharks in the harbour
Since the question of the Bull sharks presence in the harbour seems to be a topic of interest, I have collected the available resources for being informed to what the science says about that. Thanks to Dr. Amy Smoothey (a known presence in most of the videos below) for the support in putting this content together.
So, is it true that the harbour is infested with Bull sharks?
Yes and no. There is a consistent number of large (> 2m length) Bull sharks swimming throughout our harbour waterways, from the entrance to the river reaches and back , but their presence is largely seasonal as the studies have revealed.
Personally (Marco here), between November and June, I would not swim in the harbour unless I am in the most popular beaches and dive sites: Manly harbourside, Balmoral, Clifton Gardens, Camp Cove, etc.. In these sites there are dozens of divers and swimmers every day and the lack of interactions with sharks gives some statistical confidence. In the same period I would also stay clear of Middle Harbour and the area around the Spit Bridge (check out the first video below), as well as the harbour West of Clifton Gardens.
Findings by DPI:
By tagging and tracking bull sharks in Sydney Harbour we have found that:
Bull sharks occur in Sydney Harbour during summer and autumn.
Bull sharks use all areas of Sydney Harbour from Parramatta and Lane Cove Rivers to Middle and North Harbour.
Bull sharks used slightly deeper water during the day and shallower water at night.
Water temperature is a key predictor of their presence, 20-26 °C.
When water temperature drops below 19°C, bull sharks leave Sydney Harbour and travel north to QLD for the winter & spring
Information around sharks in the Sydney Harbour
An animation showing the movements of the Bull sharks in the harbour (2013)
Summary of Bull shark presence in the harbour: what we have learnt (2020)
Information around sharks in NSW
VIdeo showing the presence of White sharks along NSW (2021)
A NSW Government Shark Management Strategy video (2016)
Video on White shark tagging (2019)