Sydney swells as bull sharks patrol warming waters
Sea‑Warming Slows Bull‑Shark Visits to Sydney’s Beaches
Australia’s coastal waters are getting hotter every summer, and researchers say that could keep bull sharks in the Sydney region for almost all of the year.
Tracking 92 Migratory Sharks for 15 Years
- Scientists at James Cook University tagged 92 bull, great‑white, and tiger sharks.
- Acoustic tags recorded that bull sharks now spend an average of 15 days longer off Sydney’s coast in summer than they did in 2009.
- Records show the sharks now spend an average of 15 days longer off Sydney’s coast in summer than they did in 2009.
What the Climate Change Data Reveal
- Bondi Beach sea temperatures rose an average of 0.57 °C between 2006 and 2024.
- Remote sensing of summer sea‑surface temperatures in the area increased an average of 0.67 °C between 1982 and 2024.
- Researchers found that in winter bull sharks migrate north to Queensland when temperatures dip below 19 °C (66 °F) in Sydney.
Future Windows of Bull‑Shark Presence in Sydney Waters
According to study co‑author Nicolas Lubitz, the trend of expanding summer stay could continue, meaning that, in a few decades, bull sharks might be present for the whole year off Sydney’s coast.
Lubitz added that, while the overall chances of a shark bite remain low, the increased overlap window “means people have to be more aware” of bulls’ seasonal distribution limits.
What the Data Suggest for Other Species
- Great whites, which prefer colder waters, are losing summer habitats in northern New South Wales and Queensland.
- Evidence indicates juvenile sharks are appearing further south in rivers, hinting that breeding patterns might also shift.
Real‑Time Warning System
Tagged sharks trigger an alarm when they swim within range of a network of receivers dotted around parts of the Australian coast. The system then sends people real‑time warnings via a mobile app about shark presence at key locations.
