What happened at Coogee?

Authorities said the 35-year-old woman was swimming about 30 metres offshore when she was bitten shortly after 11am on Saturday.

A spokesperson for NSW Ambulance said the woman suffered arm and leg injuries and had been taken by road to St Vincent’s hospital, where she remains in a critical but stable condition.

Marcel Green, who leads the shark programs at the NSW Department of Primary Industries, said the woman was swimming between the flags and “doing everything right” at the time of the attack.

“It was just one of those random events,” Green told reporters on Sunday. “We can never be protected 100% at every beach, every day, all the time.”

Beaches from Bondi to Maroubra were closed for at least 24 hours.

What kind of shark was it?

Authorities have not confirmed the species but Randwick council said the shark was believed to be 3–4 metres long. Elite paddleboarder Charlie Verco, who rescued the woman, estimated it at about 3.5 metres.

“I’ve only ever seen one shark bigger than that, and that was a tiger shark in Hawaii,” he said.

Green said drone and helicopter footage taken after the attack indicated a white shark was in the area but stressed “that doesn’t mean that that was necessarily that shark”.

He said since January, the department has tagged about 60 white sharks and recorded roughly 170 detections of tagged white sharks at listening stations across NSW. However, no tagged white or tiger sharks were detected anywhere in the Sydney region on Saturday.

Chris Pepin-Neff, a shark bite policy researcher at the University of Sydney, said it was probably a white shark.

“What is really unusual is that there was a white shark at Coogee at all,” Pepin-Neff said, noting sightings there are extremely rare.

“The last white shark to be caught in the net at Coogee was in 2019 – seven years ago.”

How was it different to earlier attacks?

Pepin-Neff said water temperature was the key difference between Saturday and the summer incidents, which included the death of a 12-year-old boy and a narrow escape for an 11-year-old.

Bull sharks were responsible for the attacks over summer, Chris Pepin-Neff says. Photograph: Mike Greenslade/Australia/Alamy

“What is probably the most important variable in my 20-year history of shark attacks is water temperature: 20C and above is bull sharks, below is white sharks,” they said. “Yesterday the water at Coogee was 18C.”

Bull sharks, which were responsible for the attacks over summer, also favour murkier conditions. Experts attributed those attacks to heavy rainfall, which created turbid water that attracts smaller fish and, in turn, bull sharks hunting closer to shore.

Green similarly drew a distinction between Saturday’s attack and the bull shark activity over summer, which he said was driven by heavy rainfall flushing water from Sydney Harbour and the Hawkesbury River system into the northern beaches.

“What we saw yesterday was a quite a unique and different incident. So it wasn’t murky water. It was crystal clear,” he said.

Both Pepin-Neff and Green also said it is not unusual for white sharks to come close to shore.

Green said drone footage has captured them “well inside the surf zone”.

“Bull sharks are more of your riverine type animal, whereas white sharks, in particular, are a real surf animal,” he said.

“They really do swim up onto our beaches and along our beaches as well, and in the surf zone.”

Were the sharks hunting people?

As in the case of the summer attacks, the answer is very likely no. Experts told the Guardian in January bull sharks would have been hunting for smaller fish.

Pepin-Neff said most shark bites, particularly involving white sharks, are the result of “curiosity or defensiveness” rather than aggression.

“Both of those are terrible for humans and lead to trauma and tragedy ... but none of it is really about intentionality, because they don’t know what we are.”

What will happen now?

On Sunday, Moriarty said she had sought urgent advice from the Department of Primary Industries, which runs NSW’s shark mitigation, on how to expand the program. She did not rule out a potential cull but noted great whites were a protected species.

She said her focus would be on technology, including AI-enabled drones.

“The priority for keeping people safe is more drones in the sky, tracking and tagging more sharks, so that we can understand their movements, and people can make informed decisions … about swimming at our beaches. But nothing’s off the table,” she said.

However, shark detection drones are generally restricted at Coogee due to Civil Aviation Safety Authority rules, as the beach sits under a commercial flight path. A temporary exemption was granted on Sunday after the attack, which Moriarty said the government would seek to make permanent.

Pepin-Neff said there was no evidence to support culling as a shark bite prevention method, noting sharks are highly mobile – “so killing the one today doesn’t do anything about the one coming from Queensland”.

They said it would be better for the government to educate the public, get drones in the air and clean pipes so that there “isn’t so much sewage in the water when it rains”.

What can swimmers do to lower the risk of being bitten by sharks?

Around Australia, authorities have a common set of guidelines for swimmers to lower their risk of shark bites:

• Stay close to shore.

• Swim between the flags in patrolled areas.

• Swim with other people.

• Avoid swimming around dusk and dawn when shark activity is generally higher.

• Stay away from areas used by recreational or commercial fishers.

• Avoid swimming in river mouths, estuaries and murky waters and after heavy rainfall.

• Don’t swim with your pets.