POPULATION VIABILITY ANALYSIS OF THE FLORIDA MANATEE (TRICHECHUS-MANATUS LATIROSTRIS), 1976-1991

Recent development of age-determination techniques for Florida manatee s (Trichechus manatus latirostris) has permitted derivation of age-spe cific data on reproduction and survival of a sample of 1212 carcasses obtained throughout Florida from 1976-1991. Population viability analy sis using these data projects a slightly negative growth rate (-0.003) and an unacceptably low probability of persistence (0.44) over 1000 y ears. The main factors affecting population projections were adult sur vival and fecundity. A 10% increase in adult mortality would drive the population to extinction over a 1000-year time scale, whereas a 10% d ecrease in adult mortality would allow slow population growth. A 10% d ecrease in reproduction would also result in extinction. We conclude t hat management must focus on retaining and improving the conditions un der which manatee demography operates. The major identified agent of m ortality is boat-manatee collisions, and rapidly increasing numbers of humans and registered boats portend an increase in manatee mortality. Zoning of manatee-occupied wafers for reductions in boating activity and speed is essential to safeguard the manatee population. If boating regulations being implemented by the state of Florida in each of 13 k ey coastal counties are completed, enforced, and effective, manatees a nd human recreation could coexist indefinitely. If regulation is unsuc cessful, the Florida manatee population a likely to decline slowly tow ard extinction.