A record number of manatees have died because of Florida's lengthy winter, and so many manatees are turning up stressed by the cold that it's straining the statewide system for caring for the injured marine mammals.
So far this year the number of manatees killed by the cold is approaching 200, which Martine DeWit of the state Fish and Wildlife Research Institute called "really unprecedented."
By mid February, 301 manatees had turned up dead from various causes. The average number of deaths for this time of year over the previous five years is just 10, DeWit said.
Of that number 167 were killed by the cold, she said. Another 50 were spotted dead in the Everglades by park rangers but could not be recovered, and they are also presumed to be cold-related deaths, she said.
The St. Petersburg laboratory where biologists dissect manatees to determine what killed them has been running around the clock to keep up with the load, DeWit said.
Manatees cannot tolerate water temperatures below 65 degrees. Cold-stressed manatees tend to die slowly, with their fat depleting and their immune system failing. The manatees killed by this year's record cold have died more abruptly, with full stomachs and plenty of remaining fat on their bodies.
"It happened so quickly that even if we had been right there, I doubt we could have helped them," DeWit said.
Lowry Park Zoo spokeswoman Rachel Nelson noted that her facility has been moving animals out to make room for what they thought would be an onslaught of cold-stressed animals.
Three were moved to the South Florida Museum in Bradenton to share space with 61-year-old star Snooty the manatee — in a tank that is supposed to hold only two animals — while others were moved to Homosassa Springs Wildlife State Park.
But the onslaught of patients has not been quite as heavy as anticipated, Nelson said, because "so many of the animals just perished.''
Still, there were enough to push the manatee rehabilitation system to take some unusual steps. A pair of ailing manatees that were recently rescued in Crystal River normally would have been treated at Lowry Park Zoo in Tampa or Sea World in Orlando. Instead they had to be trucked south to the Miami Seaquarium because those closer facilities had no room.
"The staff is working overtime since the beginning of the year to respond to every animal," said Nicole Adimey, who oversees manatee rescue and rehabilitation efforts for the U.S. Fish and Wildlife Service. "This is costing everyone an enormous amount of resources."
Some manatees that have been in captivity have been released back into the wild to make room for the expected influx of more patients. This week Lowry Park Zoo released Slip, a manatee that lived most of its captive life at the Cincinnati Zoo, into Blue Springs.
On Tuesday, five more manatees that Lowry Park has cared for were released in Three Sisters Springs. One came directly from Lowry, and the other four were manatees that Lowry had sent to the Homosassa Springs Wildlife State Park around Christmas to make room.
The state spent about $600,000 last year rescuing and rehabilitating 28 manatees at Lowry Park Zoo, $315,000 rehabilitating 22 manatees at Sea World and $165,000 treating 11 manatees at the Seaquarium. Already 18 manatees have been rescued this year for treatment, Adimey said. She did not know how much money had been spent so far on the animals, but said that the enterprise has "taken an enormous amount of cooperation and jockeying around."
Adimey said it appeared that the manatees may have been holed up for too long in warm-water refuges such as Crystal River's Three Sisters Springs and various power plant outfalls. They grew hungry enough to go back out looking for food, then died from the shock of encountering the cold.
Even in the warm-water refuges, the cold has been a constant threat. Tracy Colson, a long-time manatee watcher and videographer, was at Three Sisters through most of the cold snap and said she has seen things this year she has not seen before, including manatees "shivering so hard their flippers have been shivering" and signs of frostbite.
There was one bright spot, as cold weather pushed the animals to congregate in warmer areas: Biologists were able to count a record 5,067 manatees in state waters last month.