REPRODUCTION AND DEVELOPMENT: Observations of mating herds indicate that females mate with a number of males during their 2- to 4-week estrus period, and then they go through a pregnancy estimated to last 12 to 14 months (O'Shea 1992). Births occur during all months of the year with a slight drop during winter months. Manatee cows usually bear a single calf, but 1.5 percent of births are twins. Calves reach sexual maturity at 3 to 6 years of age. Mature females may give birth every 2 to 5 years. The only long-term, stable bond between manatees is that between a cow and her calf. Weaning generally occurs between 9 and 24 months of age, although a cow and calf may continue to associate with each other for several more years. There is little information on the life-time reproductive output of females, although they may live over 50 years.

RANGE AND POPULATION LEVEL: During the winter months, the United States' manatee population confines itself to the coastal waters of the southern half of peninsular Florida and to springs and warm water outfalls as far north as southeast Georgia. Manatees also winter in the St. Johns River near Blue Spring State Park. During summer months, they may migrate as far north as coastal Virginia on the east coast and the Louisiana coast on the Gulf of Mexico.

Manatee populations also exist outside the continental United States in coastal areas of the Caribbean and Central and South America. In Puerto Rico, manatees apparently occur around the southern and eastern end of the island and around nearby Vieques Island. Except for rare sightings, manatees seem to be absent from the Virgin Islands at present, but fossils have been found in middens on St. Croix

The population of manatees in Florida has been estimated to be at least 1,865 individuals. There are an estimated 60 to 100 manatees in Puerto Rico. In the last decade, yearly mortality in Florida has averaged nearly 150 animals a year, double that of the preceding decade. The average proportion of first-year calves in the population is 10 percent with a range of 5 to 15 percent.

HABITAT: Manatees inhabit both salt and fresh water of sufficient depth (1.5 meters to usually less than 6 meters) throughout their range. They may be encountered in canals, rivers, estuarine habitats, saltwater bays, and on occasion have been observed as much as 3.7 miles off the Florida Gulf coast. Between October and April, Florida manatees concentrate in areas of warmer water. When water temperatures drop below about 21 to 22 degrees Centigrade, they migrate to south Florida or form large aggregations in natural springs and industrial outfalls. Severe cold fronts have been known to kill manatees when the animals did not have access to warm water refuges. During warmer months they appear to choose areas based on an adequate food supply, water depth, and proximity to fresh water. Manatees may not need fresh water but they are frequently observed drinking fresh water from hoses, sewage outfalls, and culverts. There is no evidence of any periodicity in manatee habitat use in Puerto Rico

CRITICAL HABITAT: The following areas in Florida (exclusive of those existing manmade structures or settlements which are not necessary to the normal needs or survival of the species) are critical habitat for the manatee: Crystal River and its headwaters known as King's Bay, Citrus County; the Little Manatee River downstream from the U.S. Highway 301 bridge, Hillsborough County, the Little Manatee River downstream from the Lake Manatee Dam, Manatee County; the Myakka River downstream from Myakka River State Park, Sarasota and Charlotte Counties; the Peace River downstream from the Florida State Highway 760 bridge, DeSoto and Charlotte Counties; and Charlotte Harbor north of the Charlotte-Lee County line, Charlotte County; Caloosahatchee River downstream from the Florida State Highway 31 bridge, Lee County; all United States territorial waters adjoining the coast and islands of Lee County; all United States territorial waters adjoining the coast and islands and all connected bays, estuaries, and rivers from Gordon's Pass near Naples, Collier County, southward to and including Whitewater Bay, Monroe County; all waters of Card, Barnes, Blackwater, Little Blackwater, Manatee, and Buttonwood Sounds between Key Largo, Monroe County; and the mainland of Dade County; Biscayne Bay, and all adjoining and connected lakes, rivers, canals, waterways from the southern tip of Key Biscayne northward to and including Maule Lake, Dade County; all of Lake Worth, from its northernmost point immediately south of the intersection of U.S. Highway 1 and Florida State Highway A1A southward to its southernmost point immediately north of the town of Boynton Beach, Palm Beach County; the Loxahatchee River and its headwaters, Martin and West Palm Beach Counties; that section of the intracoastal waterway from the town of Sewalls Point, Martin County, to Jupiter Inlet, Palm Beach County; the entire section of water known as the Indian River, from its northernmost point immediately south of the intersection of U.S. Highway 1, and Florida State Highway 3, Volusia County, southward to its southernmost point near the town of Sewalls Point, Martin County; the entire inland section of water known as the Banana river and all waterways between the Indian and Banana rivers, Brevard County; the St. Johns River including Lake George, and including Blue Springs and Silver Glen Springs from their points of origin to their confluences with the St. Johns River; that section of the Intracoastal Waterway from its confluence with the St. Marys River on the Georgia-Florida border to the Florida State Highway A1A bridge south of Coastal City, Nassau and Duval Counties.

REASONS FOR CURRENT STATUS: The manatee population was probably more abundant in the 18th or 19th century than today. Initial population decreases probably resulted from over-harvesting for meat, oil, and leather. Today, hunting is prohibited and is not considered a problem, although there is an occasional incidence of poaching. Heavy mortality does occur, however, from accidental collisions with boats and barges, and from canal lock operations.

Manatee population trends are poorly known, but deaths have increased steadily (6.1 percent a year, exponential regression, 1976 to 1991). Mortalities from collisions with watercraft are up 10.3 percent a year from 21 percent of all deaths in 1976 to 1980 to 29 percent in 1986 to 1991. Deaths of dependent calves are up 12 percent a year from 14 to 24 percent of all deaths. The combination of high mortality rates and low reproductive rates have led to serious doubts about the species' ability to survive in the United States.

Another closely related factor in the decline has been the loss of suitable habitat through incompatible coastal development, particularly destruction of seagrass beds by boating facilities. In Puerto Rico, the primary cause of manatee mortality seems to be from entanglement in gill nets. Collisions with boats and illegal killing of manatees for food may also be affecting the Puerto Rican population to some extent, but supporting data are limited.

MANAGEMENT AND PROTECTION: Based on revised recovery plan (1989) recommendations, the primary objective in the recovery of the Florida population of the West Indian manatee is to reestablish and maintain optimum sustainable populations in natural habitats throughout the manatee's historic range. To accomplish this primary objective there are several sub-objectives. They are:

A recovery plan developed specifically for the manatee population in Puerto Rico indicates three primary objectives for recovery. The first objective is to identify, assess, and reduce human-related mortality, especially that related to gill net entanglement. The second objective is to identify and minimize alteration, degradation, and destruction of habitats important to the survival and recovery of the Puerto Rico manatee population. The third objective is to develop the criteria and biological information necessary to determine whether and/or when to delist or downlist (reclassify to threatened) the Puerto Rican population of manatees.