More manatees died from cold stress this winter

Florida is on pace for another cold, harsh record year for manatee deaths, according to an environmental watchdog group.

Already, 166 manatees have died statewide, state statistics through March 2 show.

Cold spells in January and February claimed 51 manatees statewide this year, including 10 of the 22 deaths in Brevard County. 

More than 150 manatees died in just the first seven weeks of 2018, putting Florida on pace to set an annual record for manatee deaths, according to the Public Employees for Environmental Responsibility (PEER), a nonprofit government watchdog group.

“Florida’s manatees are one big freeze away from an ecological disaster and need more, not less, protection,” stated PEER Executive Director Jeff Ruch.

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Boating advocates who fight against manatee go-slow zones have long pointed out that manatee deaths are only going up because the species' population growth. Brevard and Lee counties, in particular, tend to have the most manatee deaths from all causes because they have large manatee populations lured there by seagrass habitats.

Florida's annual manatee counts have more than doubled in the past 20 years, 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 a 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.

PEER points to Florida Fish and Wildlife Conservation Commission statistics covering from Jan. 1 to Feb. 23, as a bleak start to 2018 for manatees: 

• 154 deaths in seven weeks — a death rate on pace to top last year's 538 manatee deaths and possibly the record 830 manatees deaths in 2013;  
• The biggest factor in the spike was the 51 deaths from cold stress, almost double the 27 cold-stress deaths in all of 2017 and more than double the five-year average for this cause.  In 2010, severe cold killed 282 manatees;  
• In almost a third of the cases (51), the cause of death could not be determined because the manatee was so decomposed or couldn't be recovered. 

A record 830 manatees died in 2013, including 158 of 244 manatees deaths in Brevard from undetermined causes. Biologists suspect many of those 158 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.

Last year was an unlucky year for manatees as well. The 538 manatee deaths from all causes in 2017 compare with 472 manatee deaths in 2016 and a five-year average of about 480 deaths. Brevard had 111 manatee deaths last year, including 12 deaths from cold stress.

When water temperatures stay below 68 degrees Fahrenheit for weeks at a time, manatees suffer cold-stress syndrome. That causes weight loss, fat loss, dehydration and other health problems that can kill them weeks later, PEER notes. Juvenile manatees are especially at risk. 

PEER's Ruch chided the U.S. Fish and Wildlife Service's "reduced safeguards" for the manatee because of last year's reclassification to "threatened." 

“Manatees may join polar bears as one of the first iconic victims of extinction in the wild from climate change,” Ruch said. 

That analogy goes too far, said Martine deWit, lead veterinarian at the Florida Fish and Wildlife Conservation Commission's marine mammal laboratory in St. Petersburg.

"Having studied the manatee mortality for years ... one needs to use caution in interpretation," deWit said. "We had very cold weather very early in the year. The cold stress mortality is to be expected."

PEER also points to concerns about this year's red tide killing manatees on Florida's Gulf Coast. Through March 2, red tide had claimed 10 manatees this year.

Last year, FWC identified 63 manatee deaths in which red tide was the cause or suspected cause. That compares to 53 red-tide manatee deaths in 2016, the 15 deaths in 2015 and four deaths in 2014. 

In 2013, a record 276 manatees died from red tide.

PEER also pointed to "disturbing levels of algae" in the Indian River Lagoon, the site of devastating algal bloom outbreaks in 2016.  

“As the weather warms, surviving manatees may suffer toxic shock and starvation induced by Florida’s declining water quality,” Ruch said. “Florida must start doing a better job of reducing water pollution and protecting vital warm springs habitat if it expects to restore healthy manatee populations.” 

Contact Waymer at 321-242-3663 or jwaymer@floridatoday.com Follow him on Twitter@JWayEnviro and at facebook.com/jim.waymer