The leading human-caused threat to Florida manatees is collisions with watercraft [1]. Propellers and boat hulls inflict serious or mortal wounds, and most manatees have a pattern of scars on their backs or tails after surviving collisions with boats. Scientists believe that unless this cause of death is curtailed, the manatee population will not recover.

The greatest long-term threat involves the loss of warm-water habitat [2] that manatees need to survive. Because residential development has greatly reduced the natural warm water springs use by manatees to stay warm, many of the animals aggregate in the warm-water outfalls at electric power plants on cold winter days. Scientists predict that a large percentage of the manatee population could be lost in the next few decades as aging plants are shut down.