Is it dangerous to swim in Sydney?
Bull shark activity in Sydney Harbor increases during the warmer months, expanding the season when swimmers are at risk of bites as water temperatures rise due to climate change; This is just one factor that could be causing an increase in shark bites in NSW.
The bite of a 12-year-old boy near Nielsen Park in Sydney Harbor marks the latest shark attack in the state.
It is not yet known what type of shark attacked the boy, but many bull sharks live in the harbor during this period.
What were the factors behind the attack?
While Shark Beach is covered with nets to protect swimmers during the summer months, the boy reportedly jumped from a twenty-foot rock ledge into the water outside the net.
Sydney received 126 millimeters of rain on Saturday, creating murky and dark conditions on harbor beaches where bull sharks prefer to hunt.
“The combination of brackish water, fresh water and splash action may have created the perfect storm environment for a shark attack,” NSW Police Superintendent Joseph McNulty said on Monday.
It is also the perfect time of year for bull shark activity. Sharks prefer temperatures above 22 degrees and their activity in the harbor peaks in January and February.
Kayaker Lauren O’Neill survived a bull shark attack in Elizabeth Bay around the same time of year.
The only unusual factor behind the attack, if it was a bull shark, was the time of day.
Bull sharks are crepuscular, meaning they usually hunt in the low light of dawn and dusk.
Are shark populations increasing in NSW?
There is no evidence that the populations of the three sharks most dangerous to humans (bulls, tigers and whites) are increasing.
While tiger shark numbers are declining, DNA estimates there are fewer than 500 adult breeding great white sharks along the entire Australian coastline.
But while bull sharks may not be more numerous, hunters are spending more time in Sydney.
Sharks migrate north towards Queensland each year when water temperatures drop below 20 degrees, usually between April or May.
A study published last year found bull sharks spent an extra 15 days in and around Sydney compared to 2009 due to warming waters.
“There is need to be aware of the fact that one of the top three shark species considered potentially dangerous to humans is spending more time in this area,” the lead author of the study warned. to work Dr Nicolas Lubitz from James Cook University.
Unlike white and tiger sharks, bull sharks are not a protected species in NSW.
Why are shark bites on the rise?
A four-fold increase in shark bites off the NSW coast since 2000 has been blamed mostly on white sharks, according to a study led by Flinders University shark expert Professor Charlie Huveneers.
But the factors supporting the rise are many and varied. Shark attacks are so rare that it is difficult to identify trends or attribute the increase in attacks to any one factor.
Huveneers’ review identified 40 factors that could be causing the increase in attacks.
“Human population growth, habitat alteration and destruction, declining water quality, climate change and abnormal weather patterns, and changes in the distribution and abundance of sharks and their prey are all frequently suggested to explain recent increases in shark bites,” he said.
“However, the rarity of such events reduces our ability to determine which of these factors most explains the increase in shark bites. This is likely due to a combination of these factors.”
What mitigating factors work?
The NSW government says it has the largest shark management program of its kind in the world.
The program includes seasonal nets, drone surveillance during school holidays and more than 300 SMART (Real Time Shark Management Alert) drumlines.
The SMART system works by capturing three target shark species (white, tiger and bull sharks) using baited hooks, tagging the sharks and re-releasing them one kilometer offshore.
Listening stations near popular beaches can detect the presence of a shark within 500 meters and trigger alerts.
Because shark attacks themselves are so rare and unpredictable, it is difficult to prove which mitigation efforts work best.
But Huveneers and colleagues’ analysis found no statistical difference in shark bites since 2000 between net-covered and net-free beaches.
There were no shark bites on beaches where SMART drum lines or drones were used, the researchers found, but there were 19 attacks on the same beaches before they were implemented; this “may indicate that SMART drum lines and drones could potentially reduce shark-human interactions,” he wrote.
What is your advice for staying safe?
To reduce the risk of shark bites, people should swim, dive or surf with other people, stay away from water with bleeding cuts and avoid swimming in murky water, according to the NSW government’s SharkSmart advice.
SharkSmart recommendations for swimmers and surfers
- If you see a shark, notify the lifeguard or lifeguard on duty.
- Stay close to the shore while swimming.
- Stay away from water if you have bleeding cuts or wounds.
- It is best to swim, dive or surf with others.
- Avoid swimming and surfing at dawn, dusk and night; Sharks can see you, but you can’t see them.
- Keep away from turbid, contaminated water and waters known to contain wastewater or sewage.
- Avoid areas used by recreational or commercial fishermen.
- Avoid areas with signs of bait fish or fish feeding activity; Diving seabirds are a good indicator of fish activity.
- Dolphins do not indicate the absence of sharks; They both often feed on the same food, and sharks have been known to eat dolphins.
- Be aware that sharks can be found among sand dunes or near steep slopes.
- Avoid swimming in canals and swimming or surfing in river/harbour mouths.
- Avoid having pets with you in the water.
- Stay away from shark nets and other shark mitigation measures.
- Consider using a personal deterrent.
