No. Manatees have no predators.

Researchers believe that manatees can live up to 60 years or more. Because of the many perils in the wild, however, longetivity is uncertain. In particular, recent research conducted at the Florida Fish and Wildlife Conservation Commission's Florida Marine Research Institute shows cause for concern. This research revealed that few manatees were living past the age of 30 and the majority of animals died between the age of 0 and 10 years -- nowhere near their estimated life expectancy of 60 years.Q. Were manatees ever hunted for food?
A. Florida laws to protect manatees were enacted as early as 1893. However, until the Endangered Species Act of 1973, there were no real laws to protect them. It is now illegal to hunt manatees in the United States, but they are still hunted in all other parts of their range. Most of the time it is opportunistic hunting, such as when the manatee accidentally wanders into a fisherman's net and is used for food. Poaching of manatees is the United States is extremely rare, but it still occurs.

Manatees are not usually hunted by sharks because they generally don’t share the same habitat. Larger-sized sharks are generally found offshore in deeper waters. The smaller shark species that may inhabit lagoons and shallower waters probably would not attack manatees because they are too big. Alligators do not usually attack manatees for the same reason.

All types of boats that are going too fast are dangerous to manatees. On average, most manatees only travel about three to eight kilometers (three to five miles) per hour, so any boat that is traveling faster than 24-32 kilometers (15-20 miles) per hour is capable of injuring or killing a manatee.

A single catastrophic event in 1996 was responsible for 151 manatee deaths. These manatee deaths were attributed to red tide, a term used for the proliferation or "blooms" of tiny marine organisms called dinoflagellates. The organism's pigments can cause the water to appear red, green, or yellow. Microscopic, but found in great abundance, they give off a toxic byproduct that affects the central nervous system of creatures in the area of the bloom. The red tide epizootic began on March 5 and continued through April 28 along Florida's southwest coast, wiping out approximately 15% of the known west coast population of manatees.

In 1982, another outbreak of red tide was believed to have contributed to the death of 37 manatees. Over the years however, red tide manatee mortality events have been rare. Red tide is considered to be a natural event and therefore may not be preventable. But scientists are currently looking at possibilities to reduce the risk to manatees during red tides. Monitoring and prediction of red tide distribution has been deemed crucial. The possibility of reducing water salinity in certain areas is also being investigated as red tide requires high salinity water to survive and does not do well in water less than 2.5% salt, such as brackish or river water.