Bizarre markings spotted on whale swimming at Port Macquarie NSW spark confusion among experts about what caused them

A whale with unusual markings spotted off the Australian coast has experts intrigued about their cause.

The humpback whale was spotted off Port Macquarie on the mid-north coast of NSW on Saturday by marine mammal and wildlife photographer Jodie Lowe.

The stunning images taken by Ms Lowe show white marks criss-crossing the body of the whale as it breached the surface of the ocean.

Ms Lowe told Yahoo News she saw the humpback swimming with three other whales and believed the whale is a juvenile and appeared to be healthy.

There are various theories as to what could have caused the bizarre markings.

They range from a skin condition, a lightning strike, fishing nets, cables, ship propellers or even as a result of an encounter with another whale or even a jelly fish.

Whale expert Dr Rob Harcourt described the markings as 'amazing'.

'Very intense scars like this can come from entanglement in fishing nets – though those tend to be more linear and evenly spaced,' the Emeritus Professor of Marine Ecology at Macquarie University told the outlet.

'They can also come from intraspecific fighting between males – the barnacles on the skin can cause a lot of scratching on the relatively fragile smooth skin.'

Port Macquarie is well known as an ideal whale-watching destination.

Approximately 40,000 humpback whales make the longest mammal migration in the world every year between May and November.

The whales travel over 5,000km from feeding grounds in the Antarctic to Queensland's sub-tropical waters where they breed.

The route is known as 'Humpback Highway'.

The whales then return to the Antarctic in spring with their calves at foot.  

Humpback whales are famous as the stars of whale-watching season when they breach the surface in a spectacular acrobatic display.