Bones were used for medicinal purposes. Leather made from manatee hides was prized for its thickness and used for canoes and battle shields. Missionaries used manatee oil for lamps. The Florida manatee is a federally endangered species. Many factors have contributed to its endangered status.
Humans pose the greatest threat to manatees.
Speeding boats run over manatees, submerged just below the surface, killing them either by impact or by slicing into their backs with the propellers. Manatees that survive such encounters carry distinctive scars. Sensitive manatee areas are posted with speed limits to slow boats so manatees have time to get out of the way. Flood gates and canal locks have accidentally killed manatees either by crushing or drowning them, although modified operating procedures have reduced the number of these fatalities. Fishing lines and other trash carelessly discarded into the water are also responsible for a few manatee deaths each year.