Bull Sharks Stay Longer in Warming Sydney Waters, Study Reveals

Recent research has found that bull sharks are spending more time off the coast of Sydney, with the average duration of their stay increasing by 15 days compared to 2009. This trend is linked to rising ocean temperatures, which are altering the migratory patterns of these apex predators.

Scientists from James Cook University, led by researcher Nicolas Lubitz, analyzed 15 years of data from acoustic tracking of 92 tagged bull sharks in areas like Bondi Beach and Sydney Harbour. Their findings suggest that the sharks are staying longer in the region during summer, likely due to the warming waters.

"If they’re staying longer, it means that people and prey animals have a longer window of overlap with them," Lubitz explained. This extended presence could increase the likelihood of human-shark interactions, though shark attacks in Australia remain relatively rare.

According to a national database, bull sharks, great whites, and tiger sharks are responsible for most serious shark incidents in Australia. Since 1791, there have been over 1,200 shark incidents, with more than 250 resulting in fatalities.

The study, published in the peer-reviewed journal *Science of The Total Environment*, also found that ocean temperatures around Bondi have risen by an average of 0.57°C between 2006 and 2024. Over a longer time frame, summer sea-surface temperatures in the region have increased by 0.67°C since 1982.

Lubitz warned that if the warming trend continues, bull sharks could eventually remain in Sydney waters year-round. "It could be that a few decades from now, maybe bull sharks are present year-round in waters off Sydney," he said.

While the risk of shark attacks remains low, the increased presence of bull sharks in coastal areas could require heightened public awareness. "People have to be more aware of an increased window of bull shark presence in coastal waters off Sydney," Lubitz noted.

Climate change may also impact the breeding patterns of these sharks, with early evidence showing juvenile sharks appearing in rivers further south. Additionally, the summer habitats of great white sharks, which prefer colder waters, may be shrinking in northern New South Wales and Queensland.

Tagging systems that alert people to shark presence via mobile apps are already in place, helping to provide real-time warnings along the Australian coast. These systems could become even more important as shark behavior continues to shift with the environment.