The starving manatees are easy enough to spot. You can see their ribs through their skin. They surface to breathe more than normal. Those most in need appear off balance, listing to one side.
As manatee deaths spike and Florida rescue centers fill up with manatees so malnourished that they need medical intervention, federal and state wildlife officials are taking an unprecedented step for the species: They will provide food for hundreds of manatees at a key location on the state’s east coast in an urgent effort to get them through the winter.
“The consequences are too dire not to at least give this a try,” said Patrick Rose, the executive director of Save the Manatee Club, a nonprofit group that supports the aquatic mammal.
The decision is a fraught one, because scientists have found that feeding wild animals can sometimes do more harm than good. But Florida’s manatees, already threatened with extinction, have suffered catastrophic losses over the last year. Statewide, more than 1,000 have died in 2021, a record. (In 2016, about 8,800 of the mammals remained in Florida waters, according to state wildlife officials.)
A joint task force of state and federal officials has linked the increased deaths to the loss of sea grass in the Indian River Lagoon, a 156-mile estuary where manatees, also known as sea cows, seek warm water in winter months.
The sea grass was killed off by algae blooms fueled largely by human waste and fertilizer runoff from lawns and farms, a problem decades in the making. As more people moved to the region and wastewater infrastructure aged, more waste leaked into the estuary, said Duane De Freese, a marine biologist and the executive director of the Indian River Lagoon National Estuary Program.
“The manatee situation is a symptom,” Dr. De Freese said. “In 2011, it appears we hit a tipping point.”
Since then, sea grass has died off year after year, he said, and is now down by about 90 percent. As climate change brings more severe storms and sea level rise to the region, the problem is expected to worsen.
The manatee feeding will be experimental and limited, said Mr. Rose, an aquatic biologist who pushed for it to happen. While wildlife officials are expected to announce details on Wednesday, he said the program would most likely involve produce such as cabbage and lettuce, similar to what manatees are given to eat when taken into captivity for rehabilitation.
“We hope they will take it,” Mr. Rose said. “There’s no guarantee.”
The effort comes with risks. Boat strikes also kill manatees, so further habituating them to vessels or people could be deadly. The feeding program is expected to include measures to try to prevent such collisions from happening, and to clean up any uneaten produce so that it does not fuel further algal growth.
Research focused on other species indicates that wildlife feeding, while well intentioned, can disrupt migration patterns, spread disease and lead to a cascade of other unintended consequences. Short-term benefits can evaporate over time. A study on mule deer, commissioned by Utah wildlife officials after the animals suffered during an extreme winter, found increased survival and better reproduction after two years in a group of deer that received food, but no difference after five, said Terry Messmer, a professor at Utah State University who helped lead the research. The deer that received food lingered longer in their winter range and suffered a surprising number of vehicle collisions.
But humans are already drastically altering the ecosystems that animals depend on. The important thing, Dr. Messmer said, is to proceed with caution and address the root problem.
“This is a teachable moment,” he said of the manatees. “It’s unfortunate that we’re having too many of these teachable moments in our country and the world.”