Police reported late on Tuesday that a person had been attacked by a shark about 200km south of Carnarvon, near Quobba Station.
The victim – believed to be a male surfer – suffered leg and abdominal injuries, but had been retrieved from the water and was conscious.
Emergency services are expected to take some time to attend the scene because it is a remote location.
“Initial reports suggest that the person is being conveyed by private car for assistance,” police said.
The Department of Fisheries was being sought for more information.
The attack comes six weeks after 24-year-old surfer Ben Linden was killed by a five metre great white shark some 160km north of Perth – the fifth fatal shark attack in WA waters in 10 months.
An eye-witness told ABC Radio her children had helped carry the injured man from the water after the attack, but no one in the ocean appeared to have seen the incident happen.
“The water was full of blood, that’s about it,” the woman told the ABC.
“He was conscious the whole way back though, he was OK. He was in good spirits, as well as he could be.”