Federal investigators to probe increase in Florida manatee deaths

MIAMI – Efforts to figure out what’s killing scores of manatees in Florida’s waters this year just got a big boost from the federal government.

This week, the National Oceanic and Atmospheric Administration declared Florida’s manatee crisis an “unusual mortality event,” triggering a federal investigation to determine the causes of a recent spike in deaths and directing more resources to state agencies and environmental groups involved in rescues.

As many as 539 manatees have died in Florida through March 19, according to the most recent tally by the Florida Fish and Wildlife Conservation Commission. That’s almost seven manatees per day, and nearly 400 more than the five-year average of 146 deaths. At this rate, 2021 is on track to be one of the deadliest for the gentle mammals in the past decade. A total of 637 manatees died in all of 2020, and 607 died in 2019 in the state.

Wildlife managers say that a combination of cold temperatures and a reduction of food availability in key wintering areas may explain at least part of the spike in deaths, even if the winter wasn’t as severe as in past years. The new unusual mortality event status will likely help speed up research into other factors that may be killing Florida’s beloved sea cow, including ecological and habitat degradation.

Nearly half of all deaths – 235 – occurred in Brevard County, where Indian River Lagoon provides an important refuge for the mammals to gather to escape cold water temperatures during winter months. Pollution and recent algae blooms have killed off seagrass beds in the region in recent years, leaving manatees without enough food to make it through the winter.

“We know that there’s been some water quality issues in the Indian River Lagoon and the loss of sea grasses. We don’t yet know whether that is a primary cause or just a secondary cause. And the job of the investigation is to work through all that,” said Gil McRae, director at the Fish and Wildlife Research Institute, a division of FWC, which is leading the response to the manatee mortality and the investigation.

The COVID-19 pandemic is still disrupting necropsies, which adds to questions about the staggering death numbers. Of the 539 manatee carcasses found, 372 weren’t necropsied, according to the agency. Cold stress killed 27 animals while 66 manatees died of what FWC considered natural deaths.