The 55-year-old had been surfing near Granites Beach, south of Streaky Bay, when he was suddenly attacked by the beast.
Another surfer raced out to try and help the man but he was circled by the predator.
Jeff Schmucker found the remains of the man’s surfboard with a large bite mark.
Eyewitnesses said the 55-year-old was part of a group of eight surfers in the water at the time of the attack.
One witness said: “He grabbed him, pulled him back down, brought him back up, pulled him back down again.”
Cops have launched a massive search to find him.
Police said: “The man’s body is yet to be found, and the search will continue through to day’s end.”
More to follow… For the latest news on this story keep checking back at The Sun Online.Thesun.co.uk is your go to destination for the best celebrity news, football news, real-life stories, jaw-dropping pictures and must-see video.
Like us on Facebook at www.facebook.com/thesun and follow us from our main Twitter account at @TheSun.