State wildlife biologists said of the 453 dead manatees recovered in state waters last year, more than a quarter of them were killed by "cold stress," The Miami Herald reported Thursday.
In 2010, a record high 766 manatees were found dead, with at least 282 killed by cold water, and in 2009, 429 carcasses were found, with 56 deaths blamed on cold weather.
That's a troubling increase from a five-year average of 30 cold-related deaths, experts said.
"We are concerned about the number of manatee deaths the past three years, including those resulting from exposure to cold weather," Gil McRae of the Florida Fish and Wildlife Conservation Commission said.
"Over the next few years, we will use data from monitoring programs to better understand any long-term implications for the population."
Pat Rose, executive director of the Save The Manatee Club, said protection measures mandated by state and federal wildlife agencies kept the death toll from being even worse during a near-record cold snap early in 2011.