Newcastle beaches shut over shark fears

Continued sightings of a five-metre great white shark off the Newcastle coast has closed beaches for a fourth straight day.

Newcastle City Council beach inspector Mick Body says the closure has been the longest in his memory.

"We're a little bit frustrated, especially today because it's such a nice day," he said.

"We are still searching and being cautious, we're constantly getting sightings from members of the public."

Mr Body said he was waiting for the Westpac Life Saver Helicopter to fly over the coastline and hopefully give the all clear.

The helicopter has been busy with medical emergencies throughout Tuesday.

While some surfers have found the waves too tempting, most had kept clear of the water since the shark was first seen on Saturday afternoon at Merewether Beach.

The latest sighting at Dudley beach on Tuesday morning could indicate the shark was moving south of Newcastle, reversing its northbound route overnight.

Although a jet ski has been patrolling the beaches, Mr Body said a helicopter was needed to get a good look.

"They might see more action in the ocean than we can see on a jet ski," he said.

The helicopter will be searching for a shadow of the shark close to shore or behind the break.

Increased marine activity and overcast and warm weather are thought to be possible reasons for the shark's prolonged presence.

Rob Townsend, life sciences manager at Manly Sea Life Sanctuary, said the shark's behaviour in staying close to the coastline was not unusual.

"It may be hunting eagle rays, which are a favourite food for sharks and are found close to the shore," he told AAP.

"Great whites are very variable. They spend time in the surf where they are sometimes spotted by lifeguards and then they also have their massive oceanic migration where they travel to South Africa. They are very adaptable."

He added that people were better safe than sorry and should keep out of the water while the shark continues to be spotted.