Record Cold Temps Keep Manatees Huddled
at Warm Water Refuges
Manatees overflow the refuge boundaries at Three Sisters Springs during Florida's cold snap.
"There were so many manatees they were spilling over the boundaries of the refuge," said photographer David R. Schrichte, who took this picture at Three Sisters Springs during the recent cold snap in Florida. (Photo © David R. Schrichte)

At the beginning of the year, the weather turned cold in Florida, — brr! — resulting in freezing temperatures at night and during the early morning hours. According to the National Oceanic and Atmospheric Administration, Key West recorded a record low of 42 °F (6 °C), and snow and sleet were even reported across Florida, which is a very rare event for the state. The unusually chilly temperatures lasted for nearly two weeks and brought manatees in droves to Blue Spring State Park and other warm water refuges around the state.

You might wonder how a mammal that averages 800 to 1,200 pounds could get cold, but they do. In spite of their size, manatees have relatively little body fat, and their metabolic rate is low compared to other marine mammals. These factors may account, in part, for their susceptibility to cold temperatures. “When manatees experience temperatures below 20 ° C (68 ° F) for long periods of time, they can develop a potentially fatal condition called cold stress syndrome,” says Dr. Katie Tripp, Director of Science and Conservation for Save the Manatee Club. “During prolonged periods of cold weather, manatees must choose between remaining at the warm water refuge and being hungry or enduring the cold water to go forage. Eating and digesting food helps manatees produce heat, but in the coldest situations they will often not venture from the warm water site. Manatees are faced with really difficult choices during these cold periods.”

Ranger Wayne Hartley records manatee counts at Blue Spring.
Ranger Wayne Hartley records the number of manatees using the spring run at Blue Spring State Park. (Photo by Marcy Taylor, SMC)

There was concern that manatees would be able to access warm water refuges during the chilly temperatures. In early January, the Florida Fish and Wildlife Conservation Commission (FWC) put out a news release asking boaters to avoid areas where large numbers of manatees were gathered, such as discharge canals at power plants, canal systems, or springs. At the urging of Save the Manatee Club, the U.S. Fish and Wildlife Service also asked people to stay away from Three Sisters Springs, an important warm water refuge for manatees that is part of the Crystal River National Wildlife Refuge. "It was important that manatees at these areas be left alone, because a disturbance could scare them away from the warm water they needed to survive," says Tripp.

During the cold spell, FWC staff reported 300 manatees using the warm water effluent at Tampa Electric Company’s Big Bend Power Plant near Apollo Beach, Florida. At Blue Spring State Park, where the water temperature maintains a constant 72 degrees, Ranger Wayne Hartley recorded record numbers for the season. "With a record morning count of 311 one day, we have certainly broken the record of 301 from last season," he said. “The river got down to 45 degrees, which is the lowest I have ever seen."

We were glad to hear from Ranger Wayne that all the adoptees in our Adopt-A-Manatee program had made an appearance this winter at Blue Spring except for Brutus and Troy. Brutus apparently decided to skip Blue Spring and winter instead at Silver Glen Springs, near Salt Springs, Florida. "We discovered that this year because biologist Monica Ross with Sea to Shore Alliance has been taking photos of the manatees at Silver Glen, Salt Spring, and DeLeon Springs," said Ranger Wayne. "Brutus would normally only appear four times the whole season at Blue Spring, so he might have been going to Silver Glen all along."

Hurricane the manatee showing signs of cold stress.
A photo of Hurricane, above, before his rescue, shows the effect of cold stress on manatees. (Photo by Monica Ross, Sea to Shore Alliance)

At the end of December, a manatee named Hurricane was rescued at Silver Glen Springs after he was found to be suffering from cold stress. It was exciting news because Hurricane, released at Blue Spring in February 2008, had lost his transmitter and hadn’t been sighted since July of 2008. “Of course, we want to know where did he winter last year, and where had he been this year to get into the condition he was in,” said biologist Monica Ross, who initially discovered the cold-stressed mammal. “Needless to say, we were happy and sad at the same time since his cold stress looked much worse on land after the rescue.”

After his rescue, Hurricane was transported to SeaWorld of Orlando where he is currently being treated. Other manatees were not so lucky. FWC biologists recently reported a preliminary count of 77 manatee deaths attributed to cold stress that were recorded through January 23rd — a new record — and it is likely that number will increase. Save the Manatee Club has asked waterfront residents, boaters, and other recreational users to be on the lookout for distressed and dead manatees and report cold-stressed manatees who may be in need of rescue at 1-800-404-FWCC (3922). Coming on top of record mortality figures for manatees in 2009, this is not good news.

On the positive side, Ranger Wayne predicted we might have 23 calves at Blue Spring this year. Both adoptees Lily and Phyllis have new calves, as does a manatee named Huss. “Another manatee I‘ve been watching is Ester, and she’s got a calf, too.” After enduring the cold temperatures and concern for the manatees, this was a welcome update. After all, 23 new calves are enough to make us feel warm all over.

SMC Members: You can look forward to reading more news about your manatee adoptees in the March Manatee Zone membership newsletter.

One of the 23 calves recorded at Blue Spring this season. (Photo by Buck Vallee)



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