Cause of death revealed for decapitated manatee, but questions remain as to why it happened

According to a just released report by the FWC and SFWMD, “Necropsy findings and gate operation logs suggest that the manatee attempted to pass from the upstream to downstream side when the door closed on its head and crushed it.”

MIAMI-DADE COUNTY, Fla. – On a brisk January morning, a small herd of manatees frolics and feeds in the Little River near the S-27 water control structure off Northeast 81st Street in Miami.

It’s the site where last month, Wildlife Biologist Natalie Mahomar made a gruesome discovery.

The body of a decapitated manatee was floating in the river.

Five weeks later the cause of death has finally been confirmed. The gentle sea cow was crushed by the flood gates at the structure.

According to a just released report by the Florida Fish and Wildlife Conservation Commission and the South Florida Water Management District, “Necropsy findings and gate operation logs suggest that the manatee attempted to pass from the upstream to downstream side when the door closed on its head and crushed it.”

The problem is that shouldn’t happen. Though flood gates closing on manatees was once their second leading cause of the death, since the late 1990s the State of Florida mandated that all water control gates must be outfitted with a manatee protection system that would sense the presence of the sea mammals and stop the gates from the crushing them.

So what happened on Dec. 12?

According to the report, everything was working when the incident happened:

“The last time the S-27 structure manatee protection system (MPS) was checked prior to the manatee carcass being discovered was November 28, 2020 and it was functioning properly at that time.”

The gate and sensors were inspected again when the carcass was found:

“At both times, the MPS was operating properly. Additional examinations of the electronics in January of 2021 did not find any additional information about the MPS that helped this investigation.”

Patrick Rose is an aquatic biologist and Executive Director of the Save the Manatee Club.

“I don’t know how the device could’ve been working normally and have it sustained the injuries this manatee sustained, so that is concerning,” Rose said. “I’m actually looking into it further.”

What concerns Rose is that the report also shows that around the time the manatee died, the gates attempted to close several times but couldn’t because there was something obstructing them.

“That does not sound like normal operations,” he said. “That should’ve been a big red flag.”

According to FWC, 2020 was a particularly deadly year for manatees, with 10 of them crushed or drowned in flood control structures. That’s twice the number killed by flood gates last year.

“Clearly there’s something failing more often than it should,” Rose said. “A significant number of these are aging to the point where some of the failures we’ve seen in other districts has been because of the age of the structure.”

SFWMD maintains the manatee protection systems statewide are inspected bi-monthly and there hasn’t been a fatality at S-27 since 2013.

The problem, says the district, was record rainfall last year.

“This high volume of water required much more flood control operations (gate opening/closings) than in average rainfall years,” said SFWMD spokesperson Randy Smith. “We believe this increase of flood control operations along with the high water levels creating new areas for the manatees to move in are the contributing factors for the increase in fatalities.”

That still doesn’t explain why the system appears to have failed, though.

“I really do want to dig into this and find out why it failed and what the circumstances are so we can prevent this from happening to anymore manatees,” said Rose.

The full necropsy report can be seen below:

About the Author:

Louis Aguirre returned home to Miami and Local 10 in September 2017.