The life span of manatees is 50 to 60 years. With no natural enemies and a non aggressive life style manatees have the capability of living very long lives. Few manatees live to be this old however.
Manatees are very susceptible to cold weather.
If the water temp drops below 68 F the animal become vulnerable to hypothermia. The most prevalent cause of death is due to humans. Boat collisions are the number one cause of death to manatees. Other causes are manatees being caught in locks and nets, as well as what is known as red tide. A toxic alga that eventually kills the animal.