Bull sharks in the harbour

The following is an article written in July 2021 by Marco Bordieri (founder of VIZ) and reviewed by Dr Amy Smoothey (Fisheries Scientist at NSW Department of Primary Industries). Updated on 31/1/24.

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.

Do bull sharks live 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 (see graphs below). They travel from Queensland to breed in the Sydney Harbour during Summer. Females give birth to their pups, who will spend the first years in local rivers and estuaries till they are 1-2 metres long.

Three incidents in the harbour over the last 60 years, between January and February:

• 2024:  the 29 years old Lauren O'Neill wounded in Elizabeth Bay in the evening of 29th January, 

• 2009: the 31 years old Navy diver Paul De Gelder at Woolloomooloo Bay  on 11th February (which triggered the funding of the tag and release program run by DPI during the following decade) 

• 1963: the 28 years old actress Marcia Hathaway at Middle Harbour on 28th January. 

But they are not the only ones, over the years 52 fatal attacks have taken place in Sydney, most of the times inside the Harbour.  Warning - gore images: here an article from the Daily Telegraph.

A possible guidance during those months: between November and June, I would not swim in the harbour outside netted enclosures, especially in Middle Harbour as well as in the harbour West of Clifton Gardens (see the hotspots in the graph below).
Popular beaches and dive sites like Manly harbourside, Clifton Gardens, Camp Cove have regular swimmers and scuba divers in summertime and the lack of interactions or underwater sightings gives some statistical confidence (at least till a first incident occurs).

Outside that season, I have been diving over 100 times in the harbour (up to Greenwich Point) and Middle Harbour (up to Bantry Bay), covering long distances with a sea scooter, from the shallows to the 48 m of Blues Point, day or night, and never came across any bull shark, nor I have ever met divers or snorkelers who have positively identified or photographed one (anytime of the year). That said, the risk is never zero, but if we are really keen to swim or dive anywhere in the harbour, at least we can help our luck by choosing the right season. 

Marco Bordieri

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, 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.

• 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.

• 264 bull sharks have been tagged along the NSW coast from 2009 to 2022, 87 of which inside the harbour.

• During the summer period up to 18 bull sharks have been detected in the harbour on a single day (12/2/2012)

• Tagged bull sharks have often been detected in the Great Barrier Reef during winter and spring before migrating south to Sydney Harbour and other NSW estuaries in the summer, that’s 1800 km one way!  

Bull shark fact sheet by DPI

additional 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

The Australian Shark Incident Database by Taronga Zoo

Map of shark attacks around Sydney (you can filter by accident type)

The International Shark Attack File by the University of Florida, the only comprehensive collection of worldwide attacks

Information around sharks in NSW

The incredible story of the arm thrown up by a shark in the Coogee Aquarium in 1935 and how it solved a murder case.