(ABC News) – A dog who fell off a fishing boat in the Pacific Ocean and had been “presumed dead” more than a month ago has now been found alive by Navy officials on an island 80 miles off the coast of San Diego, California.

The 1-year-old German Shepherd, named Luna, was first reported missing the morning of Feb. 10 about 2 miles off of San Clemente Island by her owner — Nick Hayworth, a fisherman — according to Sandy DeMunnik, public affairs officer for the US Navy’s Naval Base Coronado.

“He told us Luna was a very powerful swimmer and that he was 90 percent sure she’d head for shore,” DeMunnik said. “So our staff searched the island, but with no luck. He stayed in the area for two more days to look for her, and after a week, we considered her lost at sea and presumed dead.”

But this past Tuesday morning, the dog showed up to greet Navy staff arriving on the island for work.

“They saw Luna just sitting on the side of the road wagging her tail,” she said. “Keep in mind, there are no domesticated animals on the island, so it was a stunning sight.”

Navy staff were able to determine Luna was the dog who had fallen off the boat last month, DeMunnik said. She added they immediately informed Hayworth that Luna was found alive and well.

Hayworth “was actually out in the middle of a lake with horrible reception when he got the news,” DeMunnik said. “He had to do all sorts of acrobatics to get signal, but he was ecstatic — jumping up and down.”

The German Shepherd has since been examined by a wildlife biologist for the San Diego Zoo, who determined Luna was “perfectly healthy other than being a little undernourished,” DeMunnik said.

“It looks like she’d been surviving off of mice for the past few weeks,” DeMunnik said.

DeMunnik added that Luna’s survival was “incredibly remarkable,” considering the canine had to also tough out bad weather from recent El Nino storms.

Hayworth’s best friend is scheduled to pick up Luna later today and to later reunite the pup with Hayworth, DeMunnik said.