Why manatees are dying in record numbers in Florida

A record number of manatees have starved to death in Florida this year.

The state's Fish and Wildlife Conservation Commission reported 841 manatee deaths between Jan. 1 and July 2. The last time there were so many deaths was in 2013, when 830 manatee deaths were recorded over the entire year. 

"They did not have any food in their bellies," Martine de Wit, a veterinarian at the commission, told As It Happens guest host Duncan McCue.

"To help them, [we responded] to manatees that were calling to us, that were sick or injured. And we brought them into rehabilitation facilities. ... But even for those animals, it took months for them to be back into shape."

The extent to which manatees are starving became clear to De Wit when she performed necropsies, the animal version of autopsies, on the adult carcasses. 

She says the organs inside these large, aquatic mammals shrunk in size, and that it was "pretty striking" to find atrophy of their liver, fat and muscle.

Around 6,300 manatees live in Florida waters, according to the U.S. government.

In the winter and spring, they take refuge in the state's river lagoons where the waters are warmer. That's also where they normally feed on seagrass. But due to water pollution, seagrass beds have also been dying in the region.

The Indian River Lagoon, where almost half the manatees died this year, has been suffering from algal blooms since 2011. The algal blooms themselves are not toxic to manatees, says De Wit, but the blooms have slowly muddied the waters over the last decade, leading to poor water quality and clarity, resulting in little light for seagrass to grow.

"This year we reached the tipping point where there was almost nothing for [the manatees] to eat," she said. "We cannot rescue and rehabilitate them all."

Boat strikes are also a major cause of manatee deaths, killing at least 63 this year. 

Manatees were once classified as endangered by the U.S. government, but they were reclassified as threatened in 2017.

Environmentalists are now calling for the manatee to again be considered endangered.

Written by Mehek Mazhar with files from The Associated Press. Interview with Martine de Wit produced by Katie Geleff.