Bull Sharks in Sydney Harbour
- Alec Smart
- 2 days ago
- 6 min read
Updated: 1 day ago
Understanding bull sharks in Sydney Harbour and what swimmers need to know.
By Alec Smart
On Sunday 18 January 2026, a 13-year-old boy sustained severe leg injuries after he was mauled by a shark in Sydney Harbour west of Nielsen Park, Vaucluse. The beach alongside where he was swimming is named, not ironically, Shark Beach, and it features a netted swimming enclosure that is popular in summer. The boy was swimming outside of the netted area with a group of friends who were jumping off a rock.
Although the incident took place around 4.20pm, when sharks are less likely to attack, the water was reportedly turbid following days of heavy rain – which favours the ambush predator.
The shocking incident followed the tragic death of a surfer at Long Reef Beach on Sydney’s Northern Beaches in Sept 2025, who suffered catastrophic leg injuries from a white shark.
Several swimmers have been attacked by sharks in Sydney Harbour in recent years, including a woman who was bitten on the leg whilst swimming near a wharf at Elizabeth Bay in January 2024.
Sydney Harbour is a habitat for a large variety of sharks, especially during the warmer months of the year, including the three species of sharks most responsible for fatal attacks on humans: whites, tigers and bulls.
Bull-headed biters
Bull sharks (Carcharhinus leucas), a ‘shy’ predator that, as adults, range in size from 2.0 – 3.2 metres, tend to occupy shallower waters (less than five metres) but usually near steep drop-offs where they can linger in the depths and ambush prey swimming overhead.
Most of the attacks - and all of the fatalities - that resulted from deadly encounters with the dorsal finned predators within Sydney Harbour waters are credited to bull sharks.
The numerous coves around the Middle Head peninsula, from Mosman to Balmoral, and inland along Middle Harbour to Bantry Bay and under the Roseville Bridge, are among the most popular cruising zones for the more dangerous bull sharks.
A section of water between Kirribilli on the North Shore, and Garden Island and the Opera House to the south is also a ‘Bermuda Triangle’ of high bull shark activity.
Although larger sharks travel north during the cooler months, several of the mangrove-lined stretches of rivers that flow into the Sydney’s four main harbours – Pittwater, Port Jackson, Botany Bay and Port Hacking, are popular breeding grounds for the bulls.
Freshwater lurkers
Bull sharks breed in brackish (low salt) waters such as estuaries and further upstream where tidal seawater meets freshwater flowing down from creeks. Females give birth to litters of between 1 and 13 young, which remain in estuaries for up to five years.
These low-salinity environments, especially mangroves, effectively become bull shark nurseries because they offer high protection for the developing pups from predators, especially other sharks that prefer saltier waters.
Which is why bull sharks are often found in the upper reaches of Parramatta and Lane Cove rivers and Middle Harbour Creek, where tigers and white sharks seldom venture.
Bull sharks are unique because, unlike most species of shark, they’ve evolved to survive in both salt and fresh water, due to unique kidney and rectal gland functions that regulate salt and water balance. This process, called osmoregulation, makes them euryhaline (tolerant of varying salinities).
In most sharks, a significant reduction in water salinity would cause swelling and bursting of vital organs, but the bull shark’s ability to retain vital salts enables them to travel far up tidal rivers and into freshwater creeks and lakes to hunt and breed.
However, their adaptability increases the potential for dangerous attacks on humans, who favour freshwater swimming in warmer countries, where they are less likely to encounter sharks.
Attacks in Sydney Harbour
Although the first recorded shark attack fatality was off the coast of Sydney in 1791, according to the Australian Shark Incident Database, there have been 63 recorded shark bites around Sydney Harbour between 1807 (Cockle Bay, in which the victim survived) and 2025. The first documented fatality in the harbour was in Woolloomooloo Bay in 1840.
Aggressive shark interactions are divided between ‘unprovoked’ and ‘provoked’ attacks.
Unprovoked is defined as “where a shark is in its natural habitat and has made a determined attempt to bite a human where that person is not engaged in provocative activities.”
Provoked is defined as relating to “circumstances where the person attracts or initiates physical contact with a shark (accidentally or on purpose) or was fishing for, stabbing, feeding, netting, or handling a shark, or where the shark was attracted to the victim by activities such as fishing, spearfishing (where a fish has already been speared), and cleaning of captured fish.”
52 of the recorded attacks in Sydney Harbour have been identified as bull sharks, 28 of those were fatal. In fact, all of the fatal attacks around the harbour and the rivers that feed into it were attributed to bull sharks, except for one in Sirius Cove in 1919, when the species wasn’t identified.
(These statistics don’t include drowning victims eaten by opportunistic sharks, such as the Dunbar Disaster of 1857, when the remains of 97 of the 121 passengers and crew that perished were never recovered.)
Middle Harbour has a documented history of deadly shark attacks, with several fatalities occurring in the mid 20th century, mainly around Bantry Bay, Sugarloaf Bay and the Roseville Bridge.
Middle Harbour is classified as a ‘drowned valley’, which consists of varying depths. Although it has an average depth of 13 metres, there are deep channels and holes that plummet to a reported 37 metres – ideal locations for large predators to lurk undetected.
The first recorded fatality in Middle Harbour was 1907. This was followed by a tragic attack in 1916 when a Castlecrag man and his wife were bathing in shallow water off Sugarloaf Point. A bull shark bit the man’s arm, severing the main artery, and he bled to death within seconds before he was hauled ashore.
There were two more fatal attacks in 1942 in Bantry Bay, followed by Sugarloaf Bay in 1955, and beneath Roseville Bridge in 1960. The last fatal attack was in 1963, in the mouth of Middle Harbour.
Tagging
According to SharkSmart, the NSW Government shark awareness website overseen by researchers from the Department of Primary Industries (DPI), very little was known about eastern Australian bull sharks until the DPI started tagging them with electronic monitors in Sydney Harbour in 2009.
Around 90 bull sharks have since been tagged in Sydney Harbour and their movements are recorded, especially if they approach beaches with high human activity. There they alert electronic sensers and life savers will often clear the water of swimmers and surfers until the shark has left the area.
SharkSmart has found:
• Tagged bull sharks have often been detected in the Great Barrier Reef in Queensland during winter and spring before migrating south to Sydney Harbour for the summer and autumn, travelling a distance of 1800km.
• Bull Sharks are present when seawater temperatures average 20 degrees or warmer; when the water cools below 19 degrees they swim north again.
Safety Tips for Swimmers
• Avoid murky or turbid water, as it provides camouflage for ambushing sharks.
• Avoid swimming after rain, especially near river mouths, as it attracts sharks seeking drowned creatures washed downstream.
• Swim during daylight hours and avoid dawn, dusk, and overnight, when sharks are hunting.
• Check water temperature (above 20°C means more bull sharks) and use apps/websites such as Dorsal Watch for reports of recent shark sightings or electronic tag monitoring.
• Swim in netted enclosures:
North Shore: Greenwich Baths, Maccallum Pool (Cremorne Point), Clifton Gardens (Chowder Bay, Mosman), Balmoral Baths, Northbridge Baths (Sailors Bay, Middle Harbour), Clontarf Reserve Baths, Forty Baskets Beach (Balgowlah), Fairlight Beach Rockpool, Manly Cove (Manly), and Little Manly Cove (Manly).
South Shore: Dawn Fraser Baths (Balmain), Marrinawi Cove (Barangaroo), Murray Rose Pool (Double Bay), Shark Beach (Vaucluse), and Camp Cove Beach (Watson’s Bay).
To keep up to date with the latest incidents, or to make a sighting report below:
Shark Incident Database
SharkSmart
Dorsal Watch
Harbour beaches and swimming enclosures around Sydney’s North Shore
======================================