Migaloo was first spotted in 1991 passing through Byron Bay as the only known white whale in the world, and was thought to be three to five years old at the time.

There are around three other known white humpback whales named Bahloo, Willow and Migaloo Jnr.

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

In 2019, there were some concerns about the white whale's health when he was spotted heading back south at the end of July. His skin also discoloured which is another indicator of poor health.

Reports this week from the White Whale Research Centre suggest Migaloo has been spotted off the NSW South Coast.

He could pass Port Macquarie today (June 16) and be at Cape Byron any time between Wednesday and the end of the week.

Port Macquarie whale watching crews will be out on the water today to see if they can spot the white whale.

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

He said 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 and can cause discolouration, but also indicate the animal may not be well.

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.

Migaloo is believed to be over 30 years of age.

"He is now well and truly fully grown and fully mature. He's mature socially and physically," Dr Franklin said last year when observing Migaloo's migratory habits.

"It doesn't appear that he has had any issues with predators and he has an expectation to living as long as 100 years, which is the generally-believed life expectancy.

"Reports of his sightings have been available for just about every year of his life and so he has been very useful in cataloguing whale movements.

"Those sightings are very valuable in confirming migratory timing."

Researchers from Southern Cross University Whale Research Centre were able to collect sloughed skin samples from Migaloo in October 2004 when he breached. Small pieces of skin fell into the water and were collected and analysed for DNA, the White Whale Research Centre said.

From this it was confirmed that Migaloo is a male, believed to have been born in 1986. A genetic fingerprint for Migaloo was also obtained, allowing researchers to check for relatives of Migaloo amongst the other whales they have samples from, as well as to check whether Migaloo is the father if they obtain skin from a calf.

Migaloo is suspected to be an albino whale, but without definitive evidence for the moment he is known as a "hypo-pigmented" humpback.