Experts are keeping a close watch over Migaloo the white whale over fears red markings on its dorsal are skin-cancer related.

Red marks spotted on a rare white whale as it makes its way along Australia’s east coast has sparked fears the mammal may have skin cancer.

Experts are examining photos of Migaloo which last week swam the length of NSW and is now cruising toward Queensland’s far north.

White Whale Research Centre founder Oskar Peterson says photos taken by whale watchers near Sydney this week show red markings on Migaloo’s dorsal.

“It shows yellow pigmentation of its skin and that’s natural, that’s just an algae bloom,” Mr Peterson, who runs, told AAP on Wednesday.

“But it’s the red rash around his dorsal fin that’s got us a bit concerned.

“We’re just hoping that as he goes further up into warmer waters other people send in their photos so we can ascertain whether that’s a serious issue or not.”

It’s the first time he’s noticed red spots on the whale since he first began tracking Migaloo in 1996.

Mr Peterson says the whale’s skin tone may make it more susceptible to sunburn, but he’s hopeful there’ll be some other explanation for the discolouration.

The photos are being examined by an expert at Southern Cross University.

Migaloo is travelling about 8km/h as it makes its annual migration from Antarctica to the warmer waters of Queensland’s tropical north.

The whale was spotted off North Stradbroke Island earlier this week and is likely near Fraser Island on Wednesday afternoon.

Migaloo, believed to be about 28 years old, usually makes it as far north as Cooktown, north of Cairns.

Special rules apply to Migaloo and other white whales, with boats and jetskis banned from going within 500m and aircraft restricted from going within 2000 feet.

Separate rules exist for those hoping to spot a glimpse of the 20,000 less rare whales expected to cruise up and down the Queensland coast this year.