A Sydney beach has been evacuated after a shark was spotted just two days after a woman was critically injured in a shark attack at Coogee.

The shark was spotted at Bilgola Beach, on Sydney’s Northern Beaches, about 1.58pm on Monday, according to community shark alert website Dorsal.

Beachgoers were ordered from the water following the sighting.

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It was the second shark-related evacuation at Bilgola in two days, after a shark was spotted near the beach about 10.30am on Sunday.

Surf Life Saving NSW said the beach was already closed at the time because there were no patrols, volunteer lifesavers or lifeguards operating at the location during winter.

Bilgola Beach has been evacuated due to a shark sighting. Credit: Dorsal

The evacuation comes after 35-year-old Leah Stewart was attacked by a great white shark while swimming at Coogee Beach on Saturday.

Stewart suffered critical injuries and remains in hospital.

Since the attack, there have been 47 shark sightings recorded along the NSW coastline.

Surf Lifesaving NSW’s public safety manager Brent Manieri said negotiations were ongoing with the NSW government to fly drones across all of the state’s coastline to protect the public.

It follows a spate of attacks nationwide, including several bull shark bites in Sydney Harbour in January.

The latest incident has reignited calls for culls to protect swimmers, which NSW Agriculture Minister Tara Moriarty has not expressly ruled out.

But experts warn there is little evidence shark culls keep ocean-goers safer.

Adelaide University environmental science program director Brianna Le Brusque said harmful encounters with the predators were tragic and cull discussions an understandable response.

She said there was no science on how many animals would need to be removed to keep swimmers safe nor evidence it would meaningfully improve community safety.

Former prime minister Tony Abbott joined other politicians coming out strongly in favour of shark culls in the name of community safety.

“It’s so wrong that we don’t cull sharks after attacks,” he said in a video he posted on his social media.

“It’s so wrong we don’t put people before sharks.”

- With AAP