Alien-like whale carcass off Western Australia baffles boaties

Upon closer inspection the pair discovered it was an inflated whale carcass. Photo / via Facebook

Stunned fishermen spotted a gigantic alien-like ball floating off the coast of Western Australia before it was devoured by hungry sharks.

Mark Watkins and his father were fishing 25 nautical miles from Bunbury, south of Perth, on Wednesday when they came across the eerie sighting.

At first Mr Watkins, 36, thought it might be a boat, or even a stranded hot air balloon, The West Australian reported.

Upon closer inspection the pair discovered it was an inflated whale carcass.

"It's stomach was full of gas so it was all bloated up," Mr Watkins told the publication.

The whale's skin is so stretched it appears to be pink. Photo / via Facebook

"When we got closer we realised it had to be a dead whale because of the smell."

Images taken by Mr Watkins show the dead whale at bursting point.

The whale's skin is so stretched it appears to be pink.

The seasoned fishermen said they had never seen anything like it.

Upon telling their friends the fishermen were asked if there were sharks feeding on the floating carcass.

Mr Watkins said there was a four-metre white pointer shark around his boat that day.

As the pair headed into shore they noticed chunks had been bitten out of the whale and it was no longer inflated.

Southern right and humpback whales are prevalent in Australia's South West and migrate in large numbers.

Humpbacks are frequently spotted in the region from June to August each year.