WEST PALM BEACH, Fla. - A record manatee die-off in Florida this year has become so dire that federal officials are taking a once unthinkable step - feeding the wild marine mammals to help them survive the winter.

Federal and state wildlife officials announced their plans Wednesday to try to save starving manatees with a trial feeding program in the water around a power plant in Cape Canaveral.

More than 1,000 manatees, about 15% of the state's total population, have died this year. But even with a supplemental feeding program - delivering heads of lettuce and cabbage as the manatees gather in their traditional warm-water wintering spots - biologists predict that hundreds more of the iconic species are likely to perish.

Manatees rely mainly on sea grass, beds of which have been smothered by pollutants along with outbreaks of toxic algae blooms intensified by climate change.

"They're having a very hard time finding food," said Patrick Rose, executive director of the Save the Manatee Club. "The majority are quite malnourished."

A subspecies of the West Indian manatee, Florida manatees were among the first animals to be listed as an endangered species by the federal government in 1967. Numbers had dipped to about 1,000 when Rose and other biologists began a public campaign to save the manatee.

Since then, the manatees have become Florida celebrities. The Florida legislature designated the manatee the state's official marine mammal; it appears on nearly 50,000 specialty license plates; hundreds of miles of waterways have no-wake zones to slow down boats and guard against collisions with the animals; and manatee observation decks built around power plants attract thousands of tourists every winter. Nearly 40,000 people have "adopted" manatees through the Save the Manatee Club, which was founded in 1981 by singer Jimmy Buffet and then-Gov. Bob Graham, D, who went on to become a U.S. senator.

The U.S. Fish and Wildlife Service is targeting an area south of the Kennedy Space Center on the state's central Atlantic coast: the Indian River Lagoon, where more than 500 manatees have died this year. The problem is especially acute in the northern Indian River Lagoon where roughly 96% of 77,000 acres of sea grass have disappeared.

Manatees flock to the warm water discharged by power plants like Florida Power and Light Cape Canaveral Clean Energy Center in Brevard County, where the feeding experiment will take place, because they don't survive in water colder than 68 degrees. Historically, they spend winters near springs in Florida where the water temperature doesn't dip below 68 degrees.

"The question is, how do we get them through this winter?" Rose said. "Because there's no reasonable amount of food available for them within the vicinity of the power plant where they go this time of year to stay warm. So they have this miserable choice between staying warm and forgoing food, or go out and try to find it and essentially die of cold stress."

While boat strikes have ranked as the main cause of death among Florida manatees, starvation has outpaced boating accidents this year.

The plan approved by the Fish and Wildlife Service would allow limited feeding in the Indian River Lagoon, using the same "leafy greens" experts feed to manatees in captivity and at rehabilitation centers. Rose and others have been asking for permission to feed the animals since early in the year, when emaciated manatees began showing up around the state.

"We understand the importance of a timely response. Our agencies and Unified Command partners carefully considered all aspects of a short-term feeding trial," said Shannon Estenoz, Department of the Interior Assistant Secretary for Fish and Wildlife and Parks, in a statement. "It is critical we help manatees in the short term with actions that are compatible with their long-term well-being and resilience."

It remains illegal for members of the public to feed the marine mammals.

Manatees can weigh up to 1,200 pounds and measure as long as 14 feet. Rose said the animals need to eat about 10% of their body weight every day, and many have been trying to survive on algae.

They've also been seen trying to propel themselves so they can eat grass on land along canal banks.

"They're grazing on any low mangrove leaves they can find, and if there's a lawn somewhere near where they happen to be in a canal system, they're trying to eat grass off the bank," Rose said. "They are struggling."

Beth Brady, a manatee researcher at the Mote Marine Laboratory and Aquarium in Sarasota, said the feeding program could help save the lives of malnourished and emaciated manatees and guide future recovery efforts.

"I think it's a good idea," Brady said. "This is a man-made problem, and it's not going to go away quickly. It will be nice to supplement them at least a little bit. This experiment is important to see how manatees are going to respond."

After decades of recovery efforts, the number of manatees in Florida waters reached an estimated 6,620 in 2017, and federal scientists projected they would survive there for another 100 years. That same year, the Trump administration shifted the manatee from an endangered to a threatened species, over the objections of many biologists and environmentalists.

"That signaled to people that the manatee was on the path to recovery, and that it doesn't need all the help that it once did," said Jaclyn Lopez, Florida director of the Center for Biological Diversity, an advocacy group. "That was done in spite of significant opposition from the conservation community that predicted this type of catastrophe. We had waterways that were in crisis as result of water pollution. So the down-listing in 2017 was premature. And here we are, four years later, and we lost 20% of the Atlantic population in just one season."

The popularity of manatees may help push policymakers to act, Lopez said, but they must move soon.

"You look at a manatee, and it's like you're looking at a golden retriever; it looks familiar, it feels safe. They really are just gentle giants," Lopez said. "But when they're starving, and you can see their bones, you shouldn't be able to see their bones. They're supposed to be chubby, not emaciated."