The 2004 Hurricanes—Storm Attributes, Impacts to Manatee Survival Rates, and Scenarios for Population and Ecosystem Models

Beck, 2003), we detected significantly lower adult apparent survival probabilities in the northwest pan-handle of Florida in the three years with major hurricanes (Category 3 and above on the Saffir-Simpson scale) or a severe winter storm (Fig. 1). In 2004, four hurricanes impacted manatee habitat for three of the four Florida manatee subpopulations managed by the U. S. Fish and Wildlife Service. These storms had the potential for similar effects on apparent manatee survival that we observed in our 2003 study, and could affect manatee population dynamics and recovery of the species. Our hypothesis is that the magnitude of impact on the manatee subpopulations should vary with the destructiveness of the storms, which depends on wind intensity, storm surge height, size, speed of forward motion, proximity to the coast, track direc-tion relative to the coast, and coastal and ocean bottom topography. Other factors can then exacerbate or ameliorate apparent survival risk, such as density of manatees in the strike area, multiple storms within a season, or coincidence with other mortality factors (i.e., cold stress, red tide, or changes in watercraft mor-tality). The primary objectives of this research are to (1) assess the magnitude of impact to apparent manatee survival rates relative to storm characteristics, (2) identify and test hypotheses concerning the mechanisms operating to produce these impacts; and ultimately (3) develop predictive and risk assessment models t