Sydney - A marine biologist Thursday poured cold water on claims that a 7-metre great white shark is the latest visitor to a popular coastal town 100 kilometres up the coast from Sydney.

Sydney's Taronga Zoo shark expert John West cast doubt on claims by a local fisherman at the town The Entrance that he had fought off the whopper earlier this week after it tangled with his nets in the Tuggerah Lake inlet.

"It wouldn't even fit in that lake," West told Australia's AAP news agency. "A large shark like that would stick out like dog's balls."

Surf Lifesaving Club president Mick Crowe said it all might be a hoax but that no one was prepared to go in the water to find out. (dpa)