SYDNEY - A fisherman who survived treading water for 23 hours off the coast of New Zealand after falling off his boat said he was lucky to be alive after being spotted due to the reflection from his wristwatch.

Will Fransen was pulled overboard without a life jacket on Jan 2 while attempting to reel in a marlin in waters off the country's North Island.

Fransen, who said he suffered little more than wind burn and stiff joints from the ordeal, said he planned to upgrade the safety rails on his boat, which has yet to be found

He survived by treading water, while being briefly circled by a shark, before using his watch to attract the attention of a passing boat.

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"I knew my chances weren't very good – I'm usually pretty positive, but I knew my chances weren't good," he told state broadcaster TVNZ in an interview on Thursday.

James Mcdonnell, one of his rescuers, said Fransen was "incredibly pale and incredibly cold" when they pulled him from the water on the afternoon of Jan 3.

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"It's an incredible story and I don't think too many people would believe us, but hey, Will's there to tell the tale."

Fransen, who said he suffered little more than wind burn and stiff joints from the ordeal, said he planned to upgrade the safety rails on his boat, which has yet to be found.