Manatees endure another deadly year
Manatees endure another deadly year
Thirteen manatees died in unlucky collisions with boats in Brevard County this year, the most to perish that way in the county since 2010.

Statewide, 101 manatees died from boat strikes, 20 percent of this year's 513 manatee deaths. That was a typical percentage of the overall deaths but also the second highest boat-strike manatee death toll on record. Last year, a record 106 manatees died from boat strikes, according to statistics compiled by the Florida Fish and Wildlife Conservation Commission.

But boats tend to kill only about 1 percent of the manatee population, which some estimates put in the range of 8,000 or more manatees, statewide, boating advocates say. So slowing down their boats with go-slow zones shouldn't be the focus of manatee protections, some boaters assert. State biologists counter that they recover an unknown percentage of the overall manatee carcasses in any given year. Also unknown, they say, is how many of the manatees they find too rotted to tell what killed them had died from boat strikes.

"It's really random numbers, more than anything else, because you're talking about pure accidents," said Bob Atkins, president of Citizens for Florida's Waterways, a boating advocacy group with a few hundred members, mostly in Brevard. "It just comes down to a little bit of mathematical probability in space and time."

Atkins sees loss of density of seagrass beds as a much greater threat to manatees than boats. The situation is worsened, he says, by power plants that discharge warm water into coastal estuaries and bays, luring too many manatees farther north than they otherwise would be in the winter, putting them at risk of dying from cold stress or starvation.

This year's statewide manatee death toll includes 23 from cold stress; 112 from complications within a year of birth; 86 from natural causes; three from a flood gate or canal lock; 11 from other human causes; 152 for undetermined reasons; and 25 that were never recovered. according to FWC's early statistics, which run through Dec. 15.

Bob Atkins, president of Citizens for Florida's Waterways, a boating advocacy group in Brevard, says boat strikes are a very low percentage of manatees. He points to these bar graphs he created using state data.
© Bob Atkins, Citzens for Florida's WaterwaysBob Atkins, president of Citizens for Florida's Waterways, a boating advocacy group in Brevard, says boat strikes are a very low percentage of manatees. He points to these bar graphs he created using state data.
Last year, nine manatees died by boat strikes in Brevard, and a record 106 manatees died by boat strikes statewide.


"Whether we break the record or not, the number itself shows that the watercraft-related mortalities are one the main threats to manatees," said Martine deWit, a veterinarian at FWC's Fish and Wildlife Research Institute in St. Petersburg, Florida.

The 513 manatee deaths from all causes in 2017 compares with 472 manatee deaths last year and a 5-year average is 482 deaths.

The state's manatee population has grown to more than 6,600 animals, according to statewide yearly aerial and ground counts. As a result, the federal government reclassified the manatee from an endangered to threatened species, a less serious designation under the federal Endangered Species Act.

But the statewide annual counts are only a minimum count of the manatee population, so there could be thousands more.

"We've knownfor a long time that they weren't counting them all," Atkins said.

A record 830 manatees died in 2013, including 158 of 244 manatees deaths in Brevard from undetermined causes. Biologists suspect many of those manatees may have fallen victim to a seagrass die-off that disrupted the makeup of healthy bacteria in their digestive tract, leading to the disease.

DeWit says she still sees manatees that appear to be dying from the same disease, but in much smaller numbers.