It was an earlier than expected sighting of the white whale as he returns south after the annual migration along Australia's east coast.

The 30 year-old adult male was sighted off Port Douglas in early July before popping up off the Port Macquarie coast on July 29.

He was sighted by local whale spotter Leigh Mansfield.

"This year he has gone totally out of character," said Mr Mansfield.

"From my observations he did not look in good condition. He looked skinnier than normal and had a lot of discolouration on him.

"I don't know what the reason is but that's the worst I've ever seen him."

Mr Mansfield said Migaloo normally heads north past Port Macquarie in mid-July and comes back in September or October.

Dr Wally Franklin, an adjunct research fellow at Southern Cross University and founding director of The Oceania Project, said Migaloo is scientifically valuable and his health is important.

"The fact that he is heading back this early is probably unusual and there are reasons to be concerned about his condition," said Dr Franklin.

"The parasites (lice) that live on humpback whales are quite natural but when the whale can't travel at its full normal speed they are not washed off. That could be a cause of the colouration we are seeing.

"That is an indication of relatively poor health. They do become a health risk if he can not travel at his normal speed to dislodge the lice.

"The Port Macquarie sightings do raise some worrying issues and his body condition could mean there were issues with his feeding activity in Antarctica during the summer.

"Close observation should be enough to determine what the discolouration is. I'm leaning towards lice at this stage.

"If there were more sightings of Migaloo that would help fill in the details.

"He's already made incredible scientific contributions regarding timing of migratory movements.

"One hopes that we will see him back fit and healthy next season but we can't help but be concerned."

Dr Franklin said Migaloo may have travelled south due to over interactions with people, searching for migratory females to mate with or heading to feed on krill off Eden.

The 40 tonne, 15 metre whale has been given extra protections under Commonwealth Government legislation due to his uniqueness.

Vessels can be fined $16,500 if they come within 500 metres of the white whale.

Port Macquarie professional photographer Jodie Lowe, who has photographed Migaloo in 2014, 2016, 2017 and this year, said it was always a special honour to see him.

"It's always special to get photos of him and it doesn't matter how many times you see him," said Ms Lowe.

"He appeared to be underweight more than normal, more than when we have seen him in previous seasons.

"To see him like that was a bit concerning at first.

"We weren't expecting him back so soon, we were expecting to see him around September."