ST. PETERSBURG — More manatees than ever have been swimming around in Florida's waterways, scientists said Tuesday, although more than 700 have died this year, mostly from Red Tide and being hit by boats.
A new study by biologists with the Florida Fish and Wildlife Conservation Commission and the U.S. Geological Survey used data collected during aerial surveys in 2015 and 2016, combined with statistical estimation methods, to come up with a new estimate for the state's manatee population. It's between 7,520 and 10,280, the study found.
That's a considerable increase from the 5,680–8,110 manatees estimated by a previous study using data from 2011-2012. But in their study, the scientists warned against drawing any conclusions about manatees experiencing a population boom.
So much uncertainty is involved in making their estimates that "we're definitely not encouraging people to make any statements of a population increase," said lead author Jeff Hostetler, a research scientist at the Florida Fish and Wildlife Research Institute in St. Petersburg. Their findings are "not inconsistent with a population increase, but it's not certain," he explained.
But in a news release about the study's findings, state officials contended that the new estimate "contributes to the conclusion that conservation measures ... continue to create an environment that allows the manatee population to recover."
The study is the first new estimate of manatee abundance in five years. Hostetler said scientists may try to repeat the study in 2020 or 2021, but that's not guaranteed at this point.
Manatees were on the original endangered species list drawn up in 1967 because of the threats they faced from speeding boats, water pollution and loss of habitat. A lawsuit filed in 2000 by a coalition of environmental groups against state and federal wildlife agencies led to settlements requiring new boat speed zones and manatee sanctuaries. Biologists have credited those measures with spurring an increase in the population.
The U.S. Fish and Wildlife Service knocked manatees down to "threatened" instead of "endangered" last year, although a record number of manatees were killed by boaters just the year before. For the first time ever, more than 100 manatees had died after being run over by boaters.
So far this year, 117 manatees have been run over by speeding boaters — up from 102 in 2016 and 104 last year.
Meanwhile the lingering Red Tide algae bloom has been blamed for the deaths of 207 manatees this year. Of those 91 have been conclusively linked to the Red Tide toxins, and another 116 are still awaiting laboratory test results but show the symptoms of being poisoned by the algae.
Hostetler said scientists are now working on a method of estimating the impact to the population of such a large die-off of the species.
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