There has been greater interest than usual in this year s population statement due to the record high number of manatees counted in the statewide synoptic survey on January 5 th and 6 th , 2001. According to the group of specialists, aerial counts alone cannot be used to gauge the status of the population. Scientists also must consider a number of factors including number of deaths, adult survival, reproduction and population growth rates before assessing the status of manatees. Boating groups and management agencies alike have been awaiting the Working Group s interpretation of the most recent population data. Using aerial counts alone to assess the status of manatees is not good science , said Dr. James Powell a manatee biologist with over 30 years experience and Director for Aquatic Programs for Wildlife Trust.
Counts vary from year to year depending on survey conditions.
We also need to keep in mind that counts don t tell us anything about critical factors needed to assess the manatee s future survival, like the number of females in the population, the age structure of the population, the number and causes of deaths, threats and how human-related injuries and deaths may be affecting reproduction. These divisions are based primarily on manatee use of wintering sites and from radio-tracking studies of individuals movements. Although there may be some movement of manatees between regions, by focusing the analyses on these subpopulations it improves the ability to understand the local factors that affect manatee recovery, according to the panel of experts. By examining the subpopulations in these areas, biologists have found evidence that the Northwest and Upper St. Johns River groups have steadily increased over the last 25 years. While estimates of survival and population growth rates for the Southwest region are still being developed, preliminary results suggest that adult survival is similar to that for the Atlantic region.