An Australian man is recovering in hospital after being attacked by a shark while swimming in far southwestern Australia.

Jason Cull said he saw a shadow under the surface of the water, but thought it was a dolphin.

When the shark pulled him under on Saturday by grabbing a leg, he fought for his life.

"I felt along it, I found its eye and I poked it in the eye, and that's when it let go," the 37-year-old told reporters from his hospital bed in Albany on Sunday.

Albany is about 400 kilometres southwest of Perth.

Tom Marron, a spokesman for local surf lifesavers, said the attack occurred at Middleton Beach.

Beachgoers noticed three sharks on Saturday, estimating their size at up to five metres. Marron suspected the shark that attacked Cull was a white pointer.

Volunteer lifesaver Joanne Lucas went into the water to rescue Cull, he said.

"She heard the cries and splashing and knew they needed assistance and just went straight in," Marron said.

"She got hold of the injured swimmer and brought him back to shore," he said. "There was a fairly comprehensive mauling of his left leg, lost a lot of his calf, severe lacerations."

The beach has been closed.

Australia experiences about 15 shark attacks per year in its waters, one of the highest rates in the world.

On average, however, just over one per year is fatal.

A 16-year-old surfer died in April after a shark attack on Australia's eastern coast.

With files from The Associated Press