A dead manatee was found floating in waters near the Dundalk Marine Terminal, state natural resources officials said Wednesday.
Veterinarians are analyzing the carcass to determine how the animal died.
While the tropical creatures have been to wander into the Chesapeake Bay in recent decades, at this time of year local waters are too cold for them. This is the third time a dead manatee has been found in the bay, Maryland Department of Natural Resources officials said.
"With cooling weather, current Maryland water temperatures are well below a manatee's minimum survival temperature," Cindy Driscoll, the state fish and wildlife veterinarian, said in a statement.
Someone spotted the dead manatee in Colgate Creek, a tributary of the Patapsco River, and called the department last week, officials said.
It was about 9 feet long and 800 pounds, said Gregg Bortz, a spokesman for the department. Manatees are typically anywhere from 8 to 12 feet long and can weigh 500 to 1,200 pounds.
Manatees are native to the warm waters around South Carolina, Georgia and Florida, but have been spotted paddling up the Chesapeake Bay since at least 1994.
That year, a male manatee who was dubbed Chessie was first spotted. The U.S. Coast Guard airlifted him back to Florida that October, as waters cooled. He traveled even farther north, to Rhode Island, in 1995.
The U.S. manatee population is estimated at about 6,000.
Marylanders are asked to call the state natural resources department at 800-628-9944 any time they spot uncommon marine wildlife, including dolphins, manatees, sea turtles or whales.