The mammal was first spotted at approximately 7.30am this morning, Tuesday, June 29 on the western side of the Forster Tuncurry bridge cruising towards oysters leases at The Paddocks before swimming back to the bridge.

Some spectators speculated the bridge's pylons were interfering with its natural navigation instincts.

"It's been backwards and forwards; it's done about 10 circuits down to the bridge and back to the oyster leases," local photographer, Shane Chalker said.

"But, it looks very calm and relaxed," he said.

"It seems to be able to navigate the sandbanks."

A long-time resident of the Great Lakes, Mr Chalker said he had only known of whales coming into the harbour on two other occasions.

"They were humpbacks and they didn't go past the bridge."

ORRCA vice-president, Jules Farrell urged boaties, drone operators, swimmers, jet skis, kayaks and paddleboarders to stay at least 100 metres away from the whale.

"Even better, stay away completely, enjoy watching it from a distance," she said.

She said both National Parks and Wildlife, Maritime Services and the Water Police have been on the scene for much of the day to ensure onlookers kept their distance.

"The important message is not to go anywhere near this whale and spook it," she said.

"Respect the whale and give it space.

"And a drone should be no less than 100 metres above, and they cannot hover above the whale."

Ideally, ORRCA would prefer no drones were flown in the area.

"We don't want it to go up the (Wallamba) river further."

Ms Farrell said the whale appeared to be in good health and didn't have any entanglement.

Known to stay close to the shoreline, in shallower water than their humpback brothers, Ms Farrell said the whale could be a male looking for a female, or it could be a female looking for somewhere to birth.

"This is another reason to stay away; respect and give it space."

And, at the same time, she urged onlookers lining both the bridge and the shoreline to remain quiet, saying they had incredible auditory senses.

"It is doing what southern rights do at this time of year."

She was confident the mammal would eventually find its way to open water, much like four years ago when southern right came into Sydney Harbour and made its way to The Spit.

Ms Farrell said whales coming into harbours was not a common incidence.

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