Spike in Florida Manatee Deaths Linked to Human Activity, Loss of Food Sources
The first few months of 2021 have been extremely deadly for manatees as food sources in Florida have become increasingly limited, scientists say.
In the first six weeks of the new year, 317 manatee deaths were reported across Florida, CBSMiami reported. Since then, that number has risen to at least 432 deaths — about three times the normal amount of deaths in the state by this time of year, The Weather Channel reported. The five-year average for manatee deaths is 578.
"This is the worst that I've ever seen," Phil Stasik, who witnessed 13 manatee carcasses washed up on the shore of the Indian River Lagoon in Merritt Island while kayaking, said in an e-mail to Florida Today, according to The Weather Channel.
Due to limitations from the COVID-19 pandemic, the state has struggled to maintain its manatee research, usually performing necroscopies on as many manatees as possible. But over two-thirds of manatee carcasses this year have gone unrecovered, according to The Weather Channel. Until recently, this has left scientists without answers. But recent information shows that a combination of environmental conditions and human impacts may explain the tragic event, The Weather Channel reported.
"Preliminary information indicates that a reduction in food availability is a contributing factor," the FWC wrote in a statement. "While the investigation is ongoing, initial assessments indicate the high number of emaciated manatees is likely due to a decline in food availability. Seagrass and macro algae coverage in this region and specifically in the Indian River Lagoon has declined significantly."
Manatees gather in warm locales of water, according to the South Florida Sun Sentinel. They then will swim to colder areas to feed on seagrass. The problem, however, is that seagrass is increasingly limited in these cold locales, forcing the manatees to swim back, hungry and malnourished.
"A manatee will choose starvation over freezing to death," Jaclyn Lopez, Florida director of the Center for Biological Diversity, told the South Florida Sun Sentinel.
But limited food sources are not the only explanation for the manatee die-off. "It's this combination we have of cold weather, we have a reduction of where manatees can go, and in the places where manatees can go, as a consequence of human development and other activities, we have poor water quality which has resulted in these grass die-offs," Lopez added, according to the South Florida Sun Sentinel.
Sewage spills and contaminated water canals have caused this decline in seagrass, according to Patrick Rose, an aquatic biologist and executive director of the Save the Manatee Club, the South Florida Sun Sentinel reported.
In 1973, manatees were listed as "endangered" under the Endangered Species Act and only a few hundred remained. But after a dramatic recovery in 2017, where an estimated 6,620 manatees were swimming in Florida, the U.S. Fish and Wildlife Service moved the species down to "threatened," spurring controversy, The Washington Post reported.
One group that fought the decision was the Save the Manatee Club, arguing it was premature as there were no plans to reduce watercraft-related manatee deaths, The Washington Post reported, which account for 20 percent of human-caused manatee deaths and are an ongoing risk to the manatee population in Florida, The Center for Biological Diversity wrote.
Despite this year's massive die-off, the FWC still expects the manatee population in Florida to stand at about 7,000 — higher than what it was 30 years ago, according to the Orlando Sentinel. But as climate change-related events, like cold snaps, become more frequent, and the species' habitat becomes increasingly threatened by human activity and pollution, the manatee's future may be grim without further protections.
"As with all species, future resiliency is associated with population size and distribution, growth rate, health and habitat quality," the FWC wrote in a statement. "Together these factors will impact the ability of manatees to cope with future changes and are the focus of conservation work."
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