The vital number swimmers should know after Sydney Harbour shark attack: 'They're there'

If you're questioning a swim in the harbour after a 29-year-old woman was mauled in a rare shark attack, this number might help you decide.

After a young woman was badly mauled by a shark in Sydney Harbour earlier this week, a marine expert has warned Aussies the hungry animals "are there" and "always have been there" — particularly as ocean temperatures heat up.

Keen kayaker Lauren O'Neill was taking a dip off a private jetty in Elizabeth Bay, in the city's east, on Monday night when a suspected bull shark bit her on her right leg, leaving her with critical injuries. Quick-thinking bystanders, including a nearby vet who happened to be in the area, pulled her from the water and applied first aid, likely saving her life.

Dusk attack prompts temperature warning from ocean experts

While the 29-year-old has since been stabilised in hospital, the event has prompted marine experts from around the country to warn Aussies against swimming in the harbour at night, especially in the presence of people fishing and as sea temperatures increase during hot weather.

Lauren O'Neill, 29, takes a selfie in front of Potts Point at the water.
Lauren O'Neill, 29, was attacked by a shark last night at Elizabeth Bay in Sydney Harbour. Source: NCA

Robert Harcourt, leader of the Marine Predator Research Group at Macquarie University, said the animals tend to migrate down from north Queensland in search of warm water. "They're there and they've always been there in the summer," he told Sky News.

"They come down when the water is above about 21 degrees. And so, you know, if the water's warm, you know, that's a good chance that there can be bull sharks in the harbour."

The scene at Elizabeth Bay after Monday's attack.
Onlookers described the shocking scene, revealing if it weren't for the quick-thinking actions of a vet, O'Neill may not have survived. Source: NCA

Bull shark likely responsible for Sydney mauling

Speaking to Yahoo News Australia, Dr Daryl McPhee agreed with Harcourt's notion and called for people to stay out of the harbour at night.

“My thoughts are with the bite victim, who has received a life-changing injury and she needs the support of her friends and family at this time," he told Yahoo.

“I commend the action of the first responder who, in quickly applying a tourniquet, may well have saved a life. The species of shark that most likely bit the victim is a bull shark. The NSW Department of Primary Industries will likely confirm this in due course.

“Bull sharks are one of the three large species mostly responsible for serious bites and fatalities, the other two being the white shark and the tiger shark. Bull sharks are found seasonally in Sydney Harbour during the warmer months of the year."

A bull shark.
Bull sharks are known to frequent Sydney Harbour in the summer months particularly. Source: Getty

McPhee added bull sharks "are generally found in water less than five-metres deep near sharp drop-offs."

“While the risk of a shark bite is extremely low, I advise people to stay out of Sydney Harbour waters until further notice by the government," he said.

Warm waters 'definitely' attracting sharks to the area

Humane Society International marine biologist Lawrence Chlebeck earlier told Yahoo News it's not yet certain if more sharks are arriving annually in higher numbers than previous years.

"It remains to be seen if this will be a cyclical thing, or if it’s going to be happening year, after year, after year due to global warming," Mr Chlebeck said. "But those warm waters will definitely bring more bull sharks and tiger sharks to the area.

Sydney Harbour
Experts say sharks "are and always have been" in Sydney Harbour - particularly in summer. Source: Getty

"We just have to be make smart choices when entering the water. That means we're swimming with a buddy, but also not swimming in extra cloudy water, or right after it rains, or in the middle of a ball of bait fish.

"Even when there’s a higher incidence of sharks due to the warmer water, I don't think we need to be any more worried or responsible than we already are."

While shark attacks in Sydney Harbour, and in Australia more generally, are quite rare, experts say this week's events serves as a reminder to always practice caution in the sea.

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