A whale carcass that was “surfed” by a foolhardy swimmer before it washed up on a Perth beach could still attract sharks, authorities say.

A 26-year-old man, who only wanted to be known as Harrison, made world headlines after he swam from a friend’s boat to the floating humpback carcass and stood on it on Saturday.

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He later admitted his actions were stupid considering the rotting whale had attracted at least one large shark.

“Yeah, definitely a stupid act but I didn’t mean any disrespect to anyone,” he told the Seven Network.

“Mum thinks I’m an idiot. Dad’s not too proud either.”

Department of Fisheries spokesman Tony Cappelluti said the carcass, which washed up on Scarborough beach on Sunday evening, will be removed by council workers using heavy earthmoving equipment.

Scarborough and Brighton beaches remain closed for now.

Mr Cappelluti said people should stay out of the water.

“A large whale carcass is a fairly attractive food source for sharks,” he told Fairfax radio.

“And it’s likely to continue to attract them while it remains in the water and is letting off the scent and the oils that are naturally present in whales.”