|
Introduction  Article 1: First Encounter Article
2: Endangered
Article 3: Protection Conclusion: Preservation
 Manatees, of the order Sirenia, have existed for approximately 45 - 50,000,000 years. Fossils have been found in southern France, Africa, the United Arab Emirates, the South Pacific, Australia, the Caribbean, South America, and many other locations throughout the world. There are two family classifications within Sirenia; the Family Trichechidae consisting of our modern West Indian, Amazonian, and West African Manatees; and the Family Dugongidae, which included the Dugong and the Steller's Sea Cow. Tragically, the Steller's Sea Cow, which was first scientifically documented in 1741, had been hunted to extinction by 1768. Only the Dugong remains, and it, like the other manatee species, is in extreme peril.
Manatees are marine mammals. They give birth to fully developed calves weighing approximately 55-65 pounds and measuring 3.5-4.5 feet in length. While the Florida manatees do form loose groupings during the winter months when they seek the protection of warm water springs and discharge pools at power plants, they are basically solitary animals when roaming the coastal regions. The only apparent bondings are between the calves and mothers who remain together for up to two years.
As I swam with these ancient and magnificent creatures near Three Sisters Springs in Crystal River, Florida, I marveled at their grace and gentleness. It was amazing to see them walk across the sandy bottom using only their nailed front flippers which seemed small in comparison to their massive bodies. Their great paddle-shaped tails slowly pushed them through the water when they swam. Their buoyancy control was a scuba diver's dream as, with seemingly no effort, they slowly rose to the surface for a breath of air, and then descended ever more slowly in complete control.
And, therein lies one of the main reasons for their drastic decline. Air, the very substance that allows them to live may also mean their demise. Manatees are slow moving, air-breathing mammals that cannot tolerate cold temperatures since their ability to conserve heat is much less than that of land-based mammals. As winter reaches the manatees' summer range, chilling the air and water, they move south to shelter in warmer waters.
To reach those sites they travel up canals and through channels and rivers which are also used by recreational and commercial watercraft. Active manatees remain submerged from 45 seconds to 6 minutes before they return to the surface to breathe. As water temperatures cool they travel and rest closer to the water's surface where it is warmed by the sun. Surfacing for air or traveling in shallows puts them at great risk of collision with watercraft. Though they hear vessels coming, they cannot move out of harm's way in time since they are slow swimmers and are therefore vulnerable to fast moving boats.
Aerial surveys conducted in 1999 indicated a population of approximately 2,400 manatees in all of Florida. Surveys taken in early 2,000 counted only 2,222. Manatees are slow to reproduce with males taking 9 years to reach maturity and females maturing around 5 years. Single calves are born only once every 2-5 years. It is believed that, without human interference, manatees could maintain a viable population in spite of their slow reproductive rates and naturally occurring dangers. However, manatees and dugongs around the world face an ever-increasing threat from boats, pollution, loss of habitat, and development along traditional manatee waterways, indigenous hunters, and entanglement in nets and other manmade structures.
Clearly the largest, most immediate threat comes from watercraft collisions. Mortality statistics for 1999 show a total of 268 manatee deaths in Florida. Records kept since 1974 unquestionably show watercraft-related deaths run consistently between 23-31%, with boats accounting for 70% of all human-related manatee deaths. 1998 saw 66 boating-related manatee deaths. 1999 statistics documented 82 manatees killed by boats. The first 7 months of 2000 recorded approximately 60 boating-related manatee deaths with the total statewide death toll approaching 200, which is an alarming increase over the same period in 1999. The Florida manatee cannot sustain this assault. There will be no manatees in the next millenium. There will be no manatees in the next century if rapid and drastic measures are not taken.
Several organizations and agencies are involved in bringing the manatee back from the brink of extinction while others lobby for relaxed boating and waterfront property development laws to satisfy insatiable consumer demands. The challenges are great, but there are dedicated, caring people in the battle to save Florida's manatees.
© Becky A. Dayhuff 2000
Introduction Article 1: First Encounter Article
2: Endangered
Article 3: Protection Conclusion: Preservation
|
