1979a; Powell 1978; Powell and Waldron 1978). MANAGEMENT AND CONSERVATION 



POPULATION NUMBERS AND TRENDS 



Hartman (1974, 1979a) estimated the U.S. 

 population at 750 to 850 animals with possible 

 extremes of 600 and 1,000. More recent surveys 

 (Irvine and Campbell 1978) suggest a minimum 

 population between 750 and 900 animals, while 

 Brownell et al. (1978) estimated a U.S. popula- 

 tion of 1,000 or more. 



No accurate historical population estimates 

 cure available, but numbers today are believed to 

 be reduced compared to historical levels (Hart- 

 man 1971). Concern for reduced population 

 levels was expressed as early as 1880 by LeBaron 

 and 1885 by Canova. All populations throughout 

 the species' range are believed to be critically re- 

 duced (Bertram and Bertram 1973). 



United States populations appear to be in- 

 creasing in some areas, decreasing in other areas, 

 and remaining stable in some regions (Hartman 

 1974). Husar (1977) suggested that numbers were 

 increasing, but Brownell et alj (1978), based on 

 mortality figures, thought it more likely that an 

 overall decline was occuring. 



REPRODUCTION 



Mating generally involves the pursuit of an 

 estrous female by a group of courting males 

 (Hartman 1979a). Gestation, as estimated from a 

 captive conception and birth, is 365 days (Dek- 

 ker 1977). The manatee is basically uniparous, 

 with the possibility that twinning may occasionally 

 occur (Hartman 1979a). Hartman (1979a) believed 

 that there was no specific breeding season, but 

 recovery of dead calves suggests that most of 

 them are bom in the spring and early summer 

 (Hartman 1979a, Irvine et al. 1978). Calves are 

 bom and nursed in the water and are believed to 

 remain with the female for up to 2 years. Re- 

 productive maturity may be reached at 7 to 10 

 years (Odell et al. 1978). 



The most commonly observed social unit is 

 the cow and her calf, but larger social groups of 

 unknown composition are observed, especially 

 around limited resources such as warm water 

 refugia (Hartman, 1979a). 



Natural longevity is unknown, although an 

 individual has been kept in captivity in Florida 

 for over 29 years (Brownell et al. 1978). 



In addition to the Endangered Species Act, 

 manatees are protected in the United States by 

 the Marine Mammal Protection Act of 1972 (PL 

 92-522; 80 stat 1027) and by various State laws, 

 such as the Florida Manatee Sanctuary Act. 

 Manatees are also protected in every country 

 throughout their range, although enforcement 

 efforts are ineffective in most areas. 



The most immediate conservation need in the 

 United States is for management (Wray 1976). 

 Especially critical is the reduction of mortality 

 caused by boat strikes and entrapment in water 

 control structures (Hartman 1974, Campbell and 

 Powell 1976, Brownell et al. 1978). 



The State of Florida has designated Blue 

 Spring State Park as a manatee sanctuary and 

 Brevard County, Florida, has declared itself a 

 manatee sanctuary. De facto sanctuaries exist in 

 the Everglades National Park, various National 

 Wildlife Refuges throughout Florida, and several 

 Florida State Parks. Critical Habitat was designated 

 in 1976 (41 FR 41916, 24 September 1976) (see 

 range maps). 



AUTHORITIES 



Edward Asper 

 Seaworld of Florida 

 7007 Seaworld Drive 

 Orlando, FL 32809 



Robert L. Brownell, Jr. (Recovery Team) 

 National Fish and Wildlife Laboratory 

 Museum of Natural History 

 Washington, D.C. 29560 



John C. Oberheu (Recovery Team Leader) 

 Jacksonville Area Office 

 U.S. Fish and Wildlife Service 

 900 San Marco Blvd. 

 Jacksonville, FL 32207 



Daniel K. Odell 



School of Marine and Atmospheric Sciences 



University of Miami 



4600 Rickenbacker Causeway 



Miami, FL 33149 



Galen B. Rathbun 



National Fish and Wildlife Laboratory 

 412 N.E. 16th Ave., Room 250 

 Gainesville, FL 32601 



