New Threat Facing Loggerhead Sea Turtles in Florida

Winter 2001 Issue Articles:

* New Threat Facing Loggerhead Sea Turtles in Florida
* Jaguars Increase Their Take of Green Turtles at Tortuguero

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New Threat Facing Loggerhead Sea Turtles in Florida

By David Godfrey

In September of last year, dead and dying loggerhead sea turtles (Caretta caretta) began washing up on Florida beaches from Indian River County on the east coast to Charlotte County on the Gulf, with most of the turtles appearing in the Florida Keys. The live turtles all exhibited symptoms of a never-before-seen ailment in loggerheads, consisting of extreme lethargy, pneumonia and acute muscle failure in the eyes and throat. Of the 50-plus live turtles recovered to date, many have died despite best efforts to save them and none have recovered. All of the affected turtles so far have been loggerheads, and most appear to be large, otherwise robust, adults or sub-adults. Whatever is affecting these turtles apparently strikes them very fast, as they do not show signs of prolonged illness.

In addition to the live turtles that have been recovered, boaters and fishermen around the Keys have reported seeing dozens of loggerheads floating immobile offshore. It is likely that only a small portion of the affected turtles has been documented. Furthermore, the number of dead loggerheads (over 100 to date) that have stranded on south Florida beaches since the beginning of the outbreak is three times higher than what is typically seen in this area during the same time of year. While these deaths cannot yet be positively attributed to the outbreak, it appears likely that hundreds of loggerheads have already been killed by this disease. Of additional worry is the knowledge that thousands of adult female loggerheads will soon be moving into south Florida’s waters in anticipation of the 2001 nesting season. Although many of the adult female loggerheads that nest in Florida are year-round residents here, many also live on foraging grounds in the Florida Panhandle, Texas, Mexico, Cuba, and the Bahamas. When those turtles travel to south Florida to nest in a few months, they could be exposed to this disease, and if it’s contagious, cause it to spread throughout the range of this population.

Univeristy of Florida veterinarian examines one of the dead loggerheads.Photo Courtesy of John Moran / Gainesville Sun

Several Florida-based rehabilitation facilities, including the Sea Turtle Hospital in Marathon, the Marinelife Center of Juno Beach and Clearwater Aquarium, are housing and attempting to treat the live turtles. Meanwhile, veterinarians and scientists with several agencies and universities are undertaking pathological and toxicological studies to learn more about what may be causing this outbreak. The lead researchers are Dr. Elliott Jacobson with the University of Florida College of Veterinary Medicine and Ruth Ewing with the National Marine Fisheries Service (NMFS) in Miami. Unfortunately, none of the research institutions involved currently have the funds needed to sustain the investigation.

In response to this potentially devastating new threat to loggerheads, CCC is raising funds to help finance a coordinated investigation into the cause of this outbreak. A considerable amount of money can be required for this sort of investigation, so it will undoubtedly require commitments from a number of sources. The State of Florida and NMFS are scraping together some funds, but budget constraints will limit what they can do in the short term. Meanwhile, CCC has secured funds for this purpose from the Bernice Barbour Foundation and the Disney Wildlife Conservation Fund, and we are hoping to raise additional funds.

Among the potential causes to be looked at are various types of viruses, internal parasites and several kinds of toxins. One theory being investigated involves the possibility that the turtles ingested an exotic species of jellyfish reported by some fishermen in the Keys shortly before the outbreak. While evidence is still scarce, the turtles could be succumbing to a strong toxin contained in the jellyfish. Toxins found in other food sources are also being investigated. Another lead to be studied involves a series of similar infections documented in captive green turtles at the Cayman Turtle Farm in the Cayman Islands. This facility rears large numbers of green turtles in captivity for commercial and tourism purposes, potentially exposing them to new transmittable diseases, and releases some back into the sea where wild turtles might become exposed. Again, investigators are just beginning to look at these possibilities, but each lead must be studied thoroughly before being ruled out.

Many sea turtle experts consider this outbreak to be a significant threat to sea turtle recovery efforts and agree that it is extremely important to determine the cause. Loggerhead nesting in Florida has shown very encouraging trends over the past 10 years, and the specter of a devastating new disease has everyone who cares about sea turtle survival very concerned. The first order of business must be to systematically search for the cause, so that appropriate management, treatment and prevention measures can be implemented. And CCC is committed to helping facilitate an appropriate response to this crisis. If you would like more information or if you want to contribute to the effort, please call CCC at (352) 373-6441.