Bull sharks in the harbour

by Marco Bordieri

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 there are many Bull Sharks living in the harbour?

There is a consistent number of large (2-3.2m 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.

Two incidents in the harbour over the recent years: the Navy diver Paul De Gelder at Woolloomooloo Bay in February 2009 and the actress Marcia Hathaway at Middle Harbour in January 1963. But they are not the only ones, over the years 52 fatal attacks have taken place in Sydney, most of the times in the Harbour. Warning - gore images: here an article from the Daily Telegraph.

Personally, 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
87 Bull sharks have been tagged in the harbour from 2009 to 2022
During the summer period up to 18 Bull sharks have been detected in the harbour on a single day

Information around sharks in the Sydney Harbour

A study on the presence of Bull sharks in the harbour from which the following figures have been taken

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)

An 1h documentary on sharks in the harbour (2011)

Probably not the usual day for the scientists of DPI, yet 3 Bull sharks tagged in one day (1/2/2021) in locations West and East of the Harbour Bridge, length between 250 and 310 cm.