"Chessie," the Florida manatee swimming in the Atlantic Ocean hundreds of miles north of where he should be, is being tracked from space.

The 10-foot, 1,500-pound manatee, which has been fitted with a transmitter, was captured in the Chesapeake Bay last October and flown back to the warmer waters of Florida to save his life. No one knows why the manatee, dubbed Chessie, traveled so far north last year and no one knows why he returned.

But he left his native habitat near Jacksonville, Fla., on June 15 and by July 4 had entered the Bay, having traveled 525 miles in 19 days. He was later spotted near Chincoteague Island.

"No manatee has been spotted so far north before," said Jim Reid, a biologist with the National Biological Service's Sirenia Project in Gainesville, Fla.

Reid said at a late July news conference that satellite data show that Chessie may have been able to return to Florida on his own last year, if he had been given more time.

Consequently, a rescue attempt will not be made until later this year, he said.

The signals put out by Chessie are monitored by Service Argos Inc., with offices in Landover and France. They have been tracking animals from space since 1978 on satellites jointly operated by the National Oceanic and Atmospheric Administration, NASA and the French space agency.

For about $8 a reading, Argos can pinpoint an animal to within 150 meters, said Chris Estes, a company spokesman. Four times a day, Argos tries to locate the wandering manatee.

More than 800 animals are being monitored by satellite worldwide and about 20 of those are manatees, said Reid. There are fewer than 2,000 manatees left.

Reid swam up to Chessie while he rested off Hog Island, Va. to give him a new satellite transmitter because his batteries were running low.

"Most animals have them fitted around their neck. But manatees don't have necks, so we fit them around their tails," Reid said.

A padded belt at the base of the tail holds a 4-foot plastic strip. At the end of the strip is a 5 pound, 2 foot casing that floats and holds the transmitter.

"We can get readings when the animal is up to 6 feet under water," Reid said.

Manatees are endangered and can survive only in water warmer than 70 degrees. They are vegetarians who eat in shallow water, where they can be injured or killed by boat propellers.