Manatee advocates are raising concerns about the number of these gentle giants who have been killed in Florida this year. They hope that increased vigilance and other measures will help keep this from being the worst year on record.The Florida Fish and Wildlife Conservation Commission (FWC) has already counted 71 manatees killed by boats as of July 22. The numbers are already higher than they were for the same period in 2009, which was the deadliest year on record with a total of 97 deaths.