A man photographing his 10-year-old son surfing captured more than either of them bargained for when he snapped the boy sharing a wave with a shark.

Chris Hasson was taking pictures of Eden off Samurai beach, Port Stephens, eastern Australia, this week when he realised that he had photographed a twisting shark – thought to be a great white - just below the surface on an apparent collision course with his son.

“I quickly called him in and whistled,” Hasson told Associated Press. “He saw a shape in the wave and thought it was seaweed and felt something as he went over the top – he got his leg rope caught on something but he thought nothing of it until he saw the photo.”

Andrew Chin, a shark researcher at James Cook University, said it was possibly a small great white, which was “spooked and … [was] rolling away from the board to escape it”.

Eden expressed relief he did not see the animal until he was safe on the beach. “I was lucky I didn’t fall off,” he said. The encounter did not stop him getting back in the water the next day.

The incident comes after a kitesurfer’s close encounter with a great white shark off the west Australian coastearlier this month.