Marshall Islands:Officials were reacting cautiously to the Spanish-speaking man's story while they try to piece together more information. If true, the man's ordeal would rank among the greatest tales ever of survival at sea.

It's a story that almost defies belief: A man leaves Mexico in December 2012 for a day of shark fishing and ends up surviving 13 months on fish, birds and turtles before washing ashore on the remote Marshall Islands some 5,500 miles (8,800 kilometers) away.

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But that's the story a man identifying himself as 37-year-old Jose Salvador Alvarenga told the U.S. ambassador in the Marshall Islands and the nation's officials during a 30-minute meeting Monday before he was taken to a local hospital for monitoring. Alvarenga washed ashore on the tiny atoll of Ebon in thePacific Ocean last week before being taken to the capital, Majuro, on Monday.

"It's hard for me to imagine someone surviving 13 months at sea," said Ambassador Tom Armbruster in Majuro. "But it's also hard to imagine how someone might arrive on Ebon out of the blue. Certainly this guy has had an ordeal, and has been at sea for some time."

Other officials were reacting cautiously to the Spanish-speaking man's story while they try to piece together more information. If true, the man's ordeal would rank among the greatest tales ever of survival at sea.

Armbruster said the soft-spoken man complained of joint pain Monday and had a limp but was able to walk. He had long hair and a beard, the ambassador said, and rather than appearing emaciated he looked puffy in places, including around his ankles. Otherwise, he added, Alvarenga seemed in reasonable health.

Armbruster, who speaks Spanish, said the survivor told the following story:

He's a native of El Salvador but has lived in Mexico for 15 years and fishes for a man he knows as Willie, catching sharks for 25 pesos ($1.90) per pound.

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Marshall Islands castaway? Man says he survived 13 months adrift in Pacific