Hundreds of starving wild manatees have been saved by an experimental program that provided tons of lettuce to the hungry sea cows in the southern U.S. state of Florida.

The feeding program at a power plant on the state's east coast so far has provided the slow-moving marine mammals with more than 128,000 pounds (58,000 kilograms) of food financed almost entirely by donations from across the U.S. and beyond.

As the weather warms, the experimental program will now begin to wind down, wildlife officials said Wednesday.

The federal-state effort is aimed at preventing, as much as possible, another die-off of manatees like Florida saw in 2021. Last year, more than 1,100 manatees died – far above the five-year average of about 202 annual deaths – mostly of starvation because their favored seagrass source of food is disappearing due to water pollution.

This year, as of March 4, there have been 400 confirmed manatee deaths in Florida, according to the Florida Fish and Wildlife Conservation Commission. Last year at this time, the number of deaths was 430.

Ron Mezich, who oversees the manatee provisioning effort for the Florida commission, said the feeding program will continue for another week or so until the manatees move away from the winter, warm-water foraging spots.

"We're not finished with our operations this year. We're still trying to finish this year and see how it worked," Mezich said during an online news conference.

In recent days, the manatee attendance at the Florida power plant where feeding takes place has fluctuated from a high of 95 on Tuesday to a low of about 40, officials said.

"We are getting fewer animals at the feeding site," said Brian Spears of the U.S. Fish and Wildlife Service. "We are monitoring what the animals do and how they react."

About 7,500 manatees, also known as sea cows, live in Florida waters. They are listed federally as a threatened species, although there are efforts to give them the heightened endangered designation.

As of Wednesday, officials said about 83 manatees are being rehabilitated at aquariums and other facilities across the U.S., such as SeaWorld in Orlando. The Georgia Aquarium in Atlanta recently took on two young orphaned manatees, part of a larger effort by similar facilities to care for them.

The long-term solution is more difficult. Pollution from agriculture, septic tanks, urban runoff and other sources is killing the seagrass on which manatees and other creatures rely, but fixing that issue will require time and money.

Florida legislators last year provided $8 million for several seagrass restoration projects that will get off the ground this year, officials said. But it could take five years to get them done – meaning Florida's manatees may need more lettuce next winter.

"It's likely we may have to do this again," said Tom Reinert, FWC south regional director.

Wildlife officials stress that people should not feed manatees on their own because it could cause the animals to associate people with food. Anyone who sees a distressed or dead manatee should call FWC's wildlife hotline.