▶ Watch Video: Scientists using creative solutions to protect, rescue manatees after record number of deaths

A record number of manatees died in Florida last year, according to a report released by Florida Fish and Wildlife Conservation Commission this week. From January 1 to December 31, 2021, preliminary data shows that there were 1,101 reported manatee deaths in the state — nearly double the five-year average — with most dying of starvation.

Of the more than 1,000 deaths, 103 of them were watercraft-related, the state found, seven were crushed or drowned in flood gates and canal locks, and another seven were killed by human-related causes, such as poaching or rope entanglement. More than half of the deceased manatees were not necropsied or their cause of death has been undetermined. 

There are only about 6,000 manatees in all of Florida, nonprofit organization Save the Manatee previously told CBS News. 

“Having lost hundreds of manatees to starvation, that’s never happened before,” Save the Manatee’s Executive Director Patrick Rose told CBS News’ Ben Tracy. He said that the manatees that died of starvation had a “really agonizing death.” 

Preliminary mortality comparisons for the time period from January 1, 2021 to December 31, 2021.

Florida Fish and Wildlife Conservation Commission

More manatees died last year than in any of the five years prior, data shows. In 2020, there were 637 reported manatee deaths, and there were 607 in 2019. The five-year mortality average is 625, according to the state.   

The U.S. Fish and Wildlife Service has classified the surge in deaths as an unusual mortality event (UME) meaning that the issue “demands immediate response.” 

Florida officials are still investigating but have so far attributed the deaths to environmental conditions and starvation. 

“Environmental conditions in portions of the Indian River Lagoon remain a concern,” the state’s wildlife department says on its website. “Researchers have attributed this UME to starvation due to the lack [of] seagrasses in the Indian River Lagoon. In recent years, poor water quality in the Lagoon has led to harmful algal blooms and widespread seagrass loss.”

The state says that “most of the seagrass in the Indian River Lagoon has disappeared,” and that the lagoon has seen declining rates of seagrass, a staple food for manatees, since 2011. The lagoon has been hit by several algal blooms since that time, which reduces the amount of light able to hit the water and allows seagrass and other aquatic plant life to grow. 

“The effects of prolonged starvation are detrimental,” Florida Fish and Wildlife says on its website, and can result in organ atrophy, metabolic and reproductive shutdown, decreased mobility and susceptibility to disease. 

Florida Fish and Wildlife is currently initiating a supplemental feeding trial in the northern area of the lagoon, where most of the deceased manatees have been found, to provide “some aid” to manatees. 

In December, several environmental groups, Earthjustice, the Center for Biological Diversity, Save the Manatee Club, and Defenders of Wildlife, announced their intent to sue the Environmental Protection Agency over the manatee deaths, saying the agency failed to protect the mammals from water pollution. 

The groups pointed to pollution from wastewater, leaking septic systems and fertilizer runoff for the algal outbreaks and seagrass loss. 

Many environmentalists have also pointed to last year’s wastewater leak at Piney Point, a former phosphate mining facility, as a cause for the deaths. The leak, during which millions of gallons of wastewater was dumped into Tampa Bay, resulted in algal blooms on Florida’s Gulf coast. 

“It’s time for EPA to step in and enforce the Clean Water Act for the sake of the manatees and all the other creatures and people that rely on Florida’s waterways,” Earthjustice attorney Elizabeth Forsyth said in a press release. “If watching manatees starve isn’t the tipping point for the EPA to step in, I don’t know what is.” 

CBS News environmental correspondent Ben Tracy contributed to this report.