Prolonged bouts of unusually cold weather in Florida exacted a heavy toll on the state’s manatee population last year, killing a record 429 of the docile marine mammals, which are so popular among tourists, boaters and scuba divers.

But this year will be worse. Through March 19, Florida Fish and Wildlife Conservation Commission biologists had counted 431 manatee carcasses in state waters. The cause of death for the majority of these animals is being referred to as “cold stress,” or stress caused by exposure to low temperatures over a period of time.

“The unprecedented rate of mortality this year is of great concern,” said Gil McRae, director of the commission’s Fish and Wildlife Research Institute. “FWC staff, partners and volunteers have
done a tremendous job working around the clock for weeks recovering carcasses and conducting rescues throughout Florida.”

Because of higher-than-normal atmospheric pressure over the North Atlantic for much of this past winter, storm systems traveling east-to-west across the United States tracked unusually low and into the Southeastern U.S. Michael Pigott, a meteorologist with Accuweather, said temperatures in Tampa in January and February were 6.6 and 7.7 degrees below normal, respectively.

That has had an adverse effect on several wildlife species in Florida but notably its iconic manatees. The loss of so many manatees has biologists scrambling to determine long-term ramifications. That process could take several years.