What is the life expectancy of a manatee?

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In their natural habitat, the life expectancy of a manatee is 50-60 years. Manatees have no natural enemies. As with other wild animal populations, their mortality results from natural causes such as cold stress, pneumonia, gastrointestinal disease and other diseases. But due to human intrusion and activities in manatee habitats, additional fatalities are caused by collisions with watercraft, drowning or crushing in flood control structures and canal locks, entanglement in trap lines for crabs, and ingestion of litter, fish hooks and microfilament lines. The most serious threat faced by manatees in the U.S. is loss of habitat.

Challenges faced by manatees in the wild

From recent aerial synoptic surveys, there are at least 5,000 Florida manatees. But the population of the animals is still under immense pressure due to their slow reproductive and breeding rate and the incessant dangers in the wild. Manatees aren’t sexually mature until they are about 5 years old, have a gestation period of 13 months, give birth every 2-5 years and rarely give birth to twins. Although they have no documented predators, it is believed that alligators, sharks and crocodiles occasionally attack and kill Florida manatees. They also are frequently hit by watercraft and get horrible scars from boat propellers, with approximately 130 Florida manatees dying every year from boat collisions and laceration by lethal propellers.

Natural causes of manatee deaths

Manatees are quite susceptible to cold stress. Many of them tend to die during extremely cold weather. For example, at least 17 Florida manatees died from cold-related illnesses in 1996. And during the extraordinarily harsh winter of 1990, at least 46 manatees succumbed to the cold weather. Apart from cold stress, manatee deaths are caused by a variety of bacterial and parasitic diseases — just as in other animal populations. For instance, in 1996, at least 150 manatees died in southwest Florida due to a red tide organism known as Gymnodinium breve, which gives out harmful toxins. After breathing or ingesting the toxins, their organs were attacked and damaged, resulting in death.

Watercraft accidents

The vulnerability of manatees to collisions with watercraft is greatly increased by their dark color and slow swimming. Many boaters aren’t able to see manatees in the water and often spot the animals too late when collision is almost inevitable. Every year, 20-22 percent of Florida manatee deaths are caused by watercraft accidents, with collisions with barges and boats accounting for the largest proportion of human-related manatee deaths. And while engine propellers pose danger to the animals, it is collisions with boats that result in most deaths. The collisions cause internal bleeding, head injuries and upper back wounds that eventually kill the animals.

Navigation locks and floodgates

As the animals swim upstream, they may swim into and through flood gates that have been left partially open. As a result, they are trapped in the strong water current driving from the upstream side and eventually drown. Even remote-controlled flood gates can crush and drown manatees. Manatees also can be trapped in navigation locks. Entrapment in navigation locks and flood control gates are the second most leading cause of human-related manatee deaths. Between 1976 and 2018, more than 250 manatees were confirmed dead from being trapped in navigational locks and flood control gates in Florida. Recently engineers have opted to install pressure-sensitive mechanisms on flood gates that are known to be fatal for manatees, with each sensor costing about $50,000.

Poaching, vandalism and habitat destruction

Although manatees are legally protected, vandals and poachers are still responsible for a significant number of deaths. The animals are still hunted for food in some areas, while in other areas they are victims of harassment. Likewise, since the 1950s, there has been an increasing destruction of the natural habitats of coastal animals. For Florida manatees, that means continual loss of salt marshes, mangrove areas and seagrass beds which have supported their population for years. The Florida human population grows by about 1,000 people per day and approximately 250,000 acres of forests are lost annually. Today, about one-fourth of Florida remains semi-natural.

Pollution and accidental entanglement

Florida manatee deaths hit a record high of 829 animals in 2013, more than double the number of deaths in 2012. The deaths were caused largely by an upsurge in a toxic red tide, which was made worse by the increased loads of nutrients due to human waste and agricultural runoff. Even though the toxins of the red tide algae have always been present in the Mexican Gulf, the recent algae blooms resulting from increased pollution cause fatal levels of the nerve poison (brevetoxin), which when attached to the food eaten by manatees or floats in the air they inhale, leads to paralysis, suffocation and death. Manatees also have been found with crab trap lines or fishing lines wrapped tightly around their flippers, causing serious infections, amputations, and sometimes death. About 15 percent of dead manatees are found with debris in their stomach.

For additional information on manatees and manatee tours, visit the “Captain Mike’s Swimming with the Manatees” site.

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Swimming with the Manatees boasts the best water adventure in Crystal River, Florida with lots of things to do for you and your family. For more information, contact us online, or call us at (352) 571-1888.

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