The exhausted swimmer was found on a beach, and coastguards were then able to find one of the men. He had spent 30 hours at sea, clinging to debris.

The search continues for the boat's skipper.

The three fishermen were on board a trawler that sank about 15km (9 miles) off the east coast near Byron Bay.

"Judging that the second fisherman survived through the night... we can only hope that the same has occurred with the third," a spokesman for the Lifesaver Rescue Helicopter service said.

Exhausted

The fishermen were thrown into the sea early on Wednesday after their ship hit a reef, prompting a major search and rescue operation.

Hours later, fisherman Michael Williams crawled onto New Brighton Beach, north of Byron Bay.

Chris Gort, who saw Mr Williams on the beach, said the fisherman "had pretty bad cuts and bruises to his legs and his arms, he was pretty exhausted, pretty badly sunburnt".

Mr Williams raised the alarm about his two companions, and a second fisherman was picked up by a rescue helicopter 30 hours after first being thrown into the ocean.

John Jarratt was found at sea north-east of Ballina, suffering from hypothermia and dehydration.

Mr Jarratt said he and skipper Charlie Picton, an experienced fisherman, had clung to an insulated cooler after the ship went down, but that in the darkness the two became separated.

He said a rescue helicopter had apparently flown above the exhausted pair without spotting them.