Florida manatees are dying at a worrisome rate. Many appear to be starving.

At least 432 Florida manatees have already died in 2021, well over double the state’s 5-year average for the same time period.

The Fish and Wildlife Conservation Commission has not thoroughly examined many of the dead animals, but one thing is clear: A lot of manatees appear to be starving.

A severe die-off centers on the northern Indian River Lagoon on Florida’s East Coast, where experts say losses of seagrass due to persistent algal blooms have left the beloved creatures without food. This year, 179 manatee deaths have been recorded in Brevard County. By comparison, Hillsborough has seen 12 deaths, the most around Tampa Bay.

Patrick Rose, executive director of the Save the Manatee Club, said manatees have lost not just fat but muscle.

“It is a persistent, gnawing hunger, and it also weakens their ability to go about their normal physical activities,” he said. “They probably made many forays in places trying to find food where it traditionally was. ... It is not a pleasant thing.”

A Florida Fish and Wildlife Conservation Commission veterinarian told Florida Today that manatees are turning up “severely emaciated.” An agency spokeswoman said the veterinarian was not available for an interview, but the Commission has published a web page specifically devoted to the uptick.

“Environmental conditions in portions of the Indian River Lagoon remain a concern,” the Commission wrote. “Preliminary information indicates that a reduction in food availability is a contributing factor.”

Scientists are still trying to determine the exact causes of all the deaths, said Duane De Freese, executive director of the Indian River Lagoon National Estuary Program. Without those results, they are hesitant to declare that any one factor, such as hunger, is solely to blame.

“With so many manatees, some of these deaths may not be caused by the same thing,” he said. But there is “no question that this population of manatees is under significant stress because of the loss of seagrasses and appropriate forage foods.”

U.S. Rep. Charlie Crist, D-St. Petersburg, is asking the U.S. Fish and Wildlife Service to investigate, calling for the declaration of a Marine Mammal Unusual Mortality Event to free up resources. Rep. Stephanie Murphy, D-Winter Park, made a similar request this week. In 2017, federal regulators improved the manatee’s status from an endangered to threatened species, and Crist said he wants that move to be re-examined.

“While I am pleased the manatee population has largely rebounded — and this demonstrates the great success of the Endangered Species Act — I fear the decision by the previous administration may have been premature,” he wrote in a letter to an agency deputy director, calling the manatee “iconic.” “We must be doing all that we can to protect these gentle giants so future generations can take joy in seeing them splashing and swimming in Florida’s waters.”

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Rose, whose Save the Manatee Club advocates for the animals, has long said the reclassification of manatees may have come too early. Seagrass die-offs are one of his reasons why.

The Indian River Lagoon lost about 46,000 acres of seagrass between 2009 and 2019, said Charles Jacoby, a scientist with the St. Johns River Water Management District.

The main culprits are harmful algal blooms that block out sunlight the seagrass needs to survive, he said. Brown tides are fueled by excess nutrients from stormwater runoff and leaky septic tanks that reach the lagoon. Blooms turn the water murky, like pea soup.

Old waste such as lawn clippings and leaves have also settled into the waterway, Jacoby said, adding to the troublesome nutrient load. Restoring the ecosystem will take both curbing pollution and dredging the muck.

The northern Indian River Lagoon, where the recent manatee deaths have been concentrated, is a “central hub” for manatees, Rose said. Most of the perhaps 4,000 manatees along the East Coast move into the area at some point to feed, he said. Additionally, according to Rose, up to 1,000 of the manatees settle there for the winter near warm water discharged from a power plant in Brevard County.

The Fish and Wildlife Conservation Commission estimates there are at least 7,520 Florida manatees. Rose said they face many threats, foremost among them boat collisions.

Last year brought 637 total manatee deaths, according to state data, more than average. Florida is already within a couple hundred deaths of that total, not even a quarter into this year.

As waters heat up through the spring, the Fish and Wildlife Conservation Commission said, manatees could swim to other places and forage more easily. Rose said any reprieve will be temporary; he already worries about next winter.

The state, he said, must work on rescue plans and health assessments to be ready. Restoring sea grasses and cutting pollution will take more time.

Wildlife officials have reported rescuing 52 manatees through early March, including five in Brevard.

“This could even be worse next year,” Rose said. “This is a trend that if it were to continue would be very ominous, ... if this were to happen in multiple places it would be a horrific situation.”

Editor’s note: The location of the power plant has been clarified.