Warmer seas could bring more sharks to popular beaches, increasing the risk of interactions between humans and the apex predators.
In Sydney, bull sharks are spending 15 more days off the coast during summer than they did 15 years ago, due to warmer water temperatures caused by climate change.
Typically, these migratory sharks spend their winters in Queensland, chasing warming water before heading back to Sydney for some summer sun.
Year-round presence in Sydney waters
Experts predict that bull sharks will be present year-round in Sydney waters in decades to come.
“If this trend persists, which it likely will, it just means these animals are going to spend more and more time towards their seasonal distributional limit … it could be that a few decades from now, maybe bull sharks are present year-round in waters off Sydney,” said researcher Nicolas Lubitz.
Increased shark presence
While the chances of a shark bite remain low, people need to be more aware of an increased window of bull shark presence.
Dr. Lubitz added that great white shark summer habitats are likely decreasing in northern NSW and Queensland because they prefer cold water.
Little is known about interaction and competition between white and bull sharks, he said.
Shark nets and non-lethal techniques
Last month, a 16-year-old surfer survived a bull shark attack at northern NSW’s Cabarita Beach.
The teen was dragged from the water by fellow surfers after his arm was bitten before undergoing surgery.
NSW installs shark nets at 51 beaches each summer in an effort to protect swimmers and surfers.
However, there has been growing community concern about their efficacy, leading more councils to press the state government to switch to non-lethal techniques.
NSW removed its shark nets a month earlier than in previous years last summer.