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Here in Southwest Florida, the coastal waters have become an undulating morgue of sea turtles.
One hundred twenty-eight sea turtles have died or washed ashore in the waters from Manatee to Charlotte counties this year, already making it the highest year on record and more than doubling the 10-year average.
Mote Marine Laboratory recorded 77 sea turtle strandings in Sarasota County waters alone through November, making it the "highest year we've had for the 10 years we've been (monitoring sea turtle strandings)," said Deborah Fauquier, deputy manager for Mote's stranding investigations program.
The rise in strandings on the Gulf coast has not been an isolated phenomenon. Strandings have increased dramatically statewide, causing concern among some turtle experts about the animals' future.
Through Nov. 22, a record 1,655 sea turtles, mostly loggerheads and green sea turtles, have stranded in Florida waters. By year's end, that number will rise past 1,800, which nearly would double the state's 10-year average and exceed the previous high by roughly 500.
"It's certainly a concern," said Allen Foley, a wildlife biologist with the Florida Fish and Wildlife Conservation Commission. "Any time you see a large number of dead or debilitated turtles, you wonder if it's a temporary thing, or an omen of things to come."
What is most troubling, according to Foley, is that the 1,800 potential strandings represents just a fraction of the total.
"There are so many more that are never found or reported," he said.
The true total may be 10 times as high, and "that can make a pretty significant dent in the population," Foley said.
In Florida, which is one of the most productive nesting grounds for loggerhead sea turtles in the world -- 20,000 to 25,000 nest on the state's beaches each year -- a dent in the population could threaten the future of the species.
"If you lose 18,000 turtles each year, that would seem to be a loss that is not sustainable," Foley said.
The reasons for the wave of deaths vary by region. On the west coast of Florida, scientists suspect red tide blooms, which have lingered in the coastal waters most of the year.
The microscopic alga releases a toxin, known as brevetoxin, which has been known to kill fish and manatees. Foley, who is working on a paper about red tide, said the alga appears to affect sea turtles as well.
Numbers from recent years show that sea turtle strandings increase during red tide blooms and return to predictable patterns when the blooms dissipate, Foley said.
High levels of brevetoxin found in the tissues of dead sea turtles seem to bolster Foley's assertion. Many of the dead turtles were robust and displayed no obvious signs of trauma.
"(Several) were feeding right up to close to the time of death, so something had to kill them quite quickly," Foley said. "And brevetoxin can kill quickly."
While red tide has not been proven definitively to kill turtles, "there is nothing this year that would explain the increase in turtle strandings (in Southwest Florida) other than red tide," Fauquier said.
Further bolstering suspicions are the 84 manatees deaths in Southwest Florida that have been attributed to red tide. That is roughly 10 times the annual average and the second-highest year ever recorded, said Elsa Haubold, program administrator for FWC's Florida Marine Research Institute.
Mote, which is proposing a three-year study to determine whether brevetoxin causes sea turtle and dolphin deaths, rehabilitates sea turtles found foundering near red tide blooms. In most cases, a day or two after the animals are removed from the red tide-infested waters, the lethargic and disoriented animals become alert and active, Fauquier said.
While red tide is blamed for the stranding increase in Southwest Florida, the increase on the Atlantic coast remains more enigmatic.
From St. Johns County in northeast Florida to Key West, 1,130 turtles have stranded so far this year, more than double the 10-year average.
The likely cause, Foley said, was an increased incidence of disease -- about twice as many turtles succumbed to disease than normal.
"We have the same variety of infections that we've seen in the past," Foley said. "But at a much higher rate."
The reason is unknown and likely will stay that way because of the exorbitant cost to research, Foley said.
Several possibilities exist, Foley said: The turtles may have contracted the same disease, but developed a host of secondary problems that masked the initial problem; their immune systems may have become suppressed for some reason; or they may have become weak and more prone to infection from a lack of food.
The hunt for human food sources may have increased strandings in Florida's Panhandle. Many of the area's 117 strandings -- 70 in an average year - occurred in late April and early May, when a large fleet of shrimp trawlers was operating offshore.
During that time, 18 beheaded and flipperless turtles washed ashore on Panhandle beaches. In each case, knives were used.
"I've been on the stranding program for six years, and it's always upsetting to see a turtle wash up," said Nancy Evou, a biology technician with the National Marine Fisheries Service in Panama City Beach. "But it was especially upsetting under these circumstances."
Foley and Evou suspect shrimpers, angry at turtles for destroying their catch, may have carved up the turtles out of frustration. Investigators from FWC and the National Marine Fisheries Service investigated the mangled turtles but made no arrests. When law enforcement increased patrols in early May, the number of strandings returned to normal levels.
A red tide bloom in October and November may have added to the region's increase as well, Foley said.
While strandings have increased steadily since the state started keeping count in 1980, Foley said he hopes this year was an anomaly, "because what happens here has a worldwide impact."
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