Of the 565 manatees that died statewide last year, 17 died from floodgates or navigational locks: about 3 percent of all deaths, according to Florida Fish and Wildlife Conservation Commission data. That’s a higher number than what’s typical, at least recently, according to FWC veterinarian Martine de Wit.
“It is higher than average,” de Wit said.
Manatees often swim through water control structures, like navigational locks, which help boats pass through dams. Sometimes, manatees will get stuck in the doors of those structures once they close; other times, they drown after being sucked into turbulent waters near the structures, de Wit said.
“This was recognized years ago: that it was an extra threat to manatees, so efforts were made to provide as much protection as possible,” de Wit said. “So there are many structures now that are outfitted with devices that will detect when a manatee is between the doors, and it prevents the doors from further closing and crushing the manatee.”
Still, accidents can happen, de Wit said. As a human-driven and therefore preventable cause of manatee death, floodgate issues are a priority for FWC and other partner agencies, who work together to identify potential solutions, she said.
“Any time when there's a manatee carcass at a structure, we investigate why the carcass died, and then follow up with the structure to see if there could be a malfunctioning of the protection devices, or if there are any other adjustments that have to be made to prevent such accidents again,” de Wit said.
FWC data show 19 manatees also died from water control structures in 2022. But the state’s five-year average for such deaths is 10 of 739 total deaths, on average, since 2019. Proportionally, fewer deaths are attributed to floodgates now than in past years, de Wit said.
“[Floodgate deaths] were relatively high in the past, even when the total carcass numbers were lower. And you actually saw a significant drop when those [protective] devices were added,” de Wit said.
In Brevard County, five manatees were killed by floodgates last year, more than in any other county. All five were adults and died in Port Canaveral.
Hurricanes also posed a challenge for manatees last year, with FWC and partners rescuing a total 19 that were trapped in higher, drier areas after flooding and storm surge receded. At least one death was attributed to Hurricane Helene.
Although most of those manatees were found on the Gulf Coast, one in Brevard County is still being rehabilitated, de Wit said, along with six others found elsewhere that are still receiving care. Twelve of the trapped manatees have since been released.
“We got reports shortly after the storms, when manatees were in visible areas,” de Wit said, adding that months later, trapped manatees were still being discovered: including one found in a mud pool around Thanksgiving, amid cold temperatures.
Cold temperatures continue to pose a challenge for manatees right now, as Florida experiences an early start to winter, de Wit said.
“It's always the season where manatees face that extra threat of cold stress, and especially the young ones. We now have more young, inexperienced manatees, so that concern for cold stress is real,” de Wit said.
As manatee reproduction continues bouncing back from 2021’s record die-off, FWC staff are tracking more live manatee calves — along with more perinatal deaths. But so far, examinations of those carcasses don't reveal any new infections or viruses of concern, de Wit said.
“I see that as a normal occurrence when you have healthy reproduction going on, because there's always a percentage that does not make it,” de Wit said.
“Perinatal” means the time around birth, although not every single manatee assigned to that category is necessarily young, de Wit said. Any manatee less than five feet long at the time of death is assigned to the perinatal category.
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The ongoing, yearly challenge of colder temperatures prompts many manatees to flock to warmer Central Florida waters. Manatees can develop cold stress lesions also known as “Florida frostbite,” presenting as white spots that sometimes turn into ulcers and abscesses.
If you see any manatee with those lesions; or any other manatee of concern, you should report it to FWC’s Wildlife Alert Hotline: 1-888-404-3922. Reports made to that hotline are how the agency learned of all the manatees rescued after last year’s storms.
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