Abstract

On January 5, 2010, a 358 kg, 144cm straight carapace length (SCL) adult female leatherback sea turtle (Dermochelys coriacea) was admitted into the Sea Turtle Rehabilitation Hospital at Mote Marine Laboratory. The animal was initially sighted on the beach in Collier County (FL) on January 4, exhibiting confusion and behavior possibly consistent with a nesting attempt disturbed by human activity. The turtle was physically encouraged to return to the water several times throughout the day and eventually swam away. She returned to a more remote beach in Lee County the following day, and was exhibiting similar behavior. While the possibility exists that the turtle was engaged in a nesting attempt, nesting this early in the year has never been reported along the Gulf Coast of Florida and is only rarely seen in the Northwest Atlantic region.¹ In addition, a permanent flipper tag affixed to one rear flipper had been issued to a group tagging turtles in Columbia (South America) in 1999. Although no report was filed to specify the tagging location and circumstances, this raises the possibility this individual may have nested much further south in the past. Consequently, the decision was made to admit the animal into captivity on a temporary basis for diagnostic examination.

There have been infrequent attempts to rehabilitate adult leatherback sea turtles. To date, only very short-term rehabilitations, of fewer than 3 days, have resulted in a live release.² More extended attempts have resulted in mortality, commonly along with significant injuries secondary to captivity.³ The extremely large size of the animal, coupled with its pelagic nature and delicate epidermis, present a unique set of challenges. Adapting designs previously developed for housing juvenile leatherback turtles and for attachment of tracking equipment to free-ranging adults, a harness was constructed from neoprene rubber and nylon webbing straps covered with flexible plastic hosing to minimize friction at contact points.^4-6 The harness was suspended above the center of a 10 meter diameter marine mammal rehabilitation pool with enough tether to allow the animal full mobility, but to prevent contact with the walls and bottom of the tank. Integrated within the tether was an elastic shock absorber (Shockles^©, Hood River, OR 97031, USA) to ease tension while preventing excess slack in the line and potential entanglement. The turtle was monitored around-the-clock for any signs of distress, and spent the duration of rehabilitation swimming continuously and breathing at a rate of approximately one respiration every 1-2 minutes. Reports from leatherback sea turtle biologists indicate this is normal behavior for animals in this situation.

Blood samples were collected from the interdigital veins of the rear flippers several times throughout the rehabilitation for complete blood counts and plasma chemistry panels; blood cultures and heavy metal analysis were submitted at the time of admission.⁷ Comparison of these values with wild nesting leatherback populations showed no clear signs of infection or other systemic disease.⁸ Heavy metal analysis results became available after release of the animal, and showed an extremely high level of arsenic (990mcg/L), a trace heavy metal that was only minimally detectable in a previous study of wild leatherbacks.⁸ Repeat analysis confirmed this value, but the significance of this finding remains unknown, and interpretation is complicated by lack of the appropriate sampling tube (Royal blue top) and potential contamination from the blood collection tubes used (BD Vacutainer^® with lithium heparin additive, Franklin Lakes, NJ 07417, USA). Investigations are in progress to determine if the collection tube might be a source of the arsenic.

Several superficial wounds were present on the soft tissues at the time of stranding and additional small abrasions were acquired during handling and transport, but there was no evidence of significant trauma sustained by the turtle. Ultrasound findings were consistent with a reproductively active female with follicles in various stages of development. A single 0.25 mg/kg dose of dexamethasone sodium phosphate (DexaJect SP; Butler Animal Health, Dublin, OH 43017 USA) was administered in subcutaneous fluids upon admission. Two doses of ceftazidime (Tazicef; Hospira, Inc, Lake Forest, IL 60045, USA) were administered intramuscularly at 22 mg/kg approximately 42 hours apart, as well as two doses of enrofloxacin (Baytril; Bayer Animal Health, Shawnee Mission, KS 66201, USA) administered in subcutaneous fluids at 10 mg/kg on days 2 and 3 of rehabilitation. Plasma levels are being analyzed for concentration of ceftazidime at the 40 hour mark and enrofloxacin at the 18 hour mark for future treatment references.

Due to diagnostic and physical examination results indicating a relatively healthy animal, early signs of pressure ulcers secondary to the harness system, deteriorating sea/weather forecasts affecting boat travel, and the difficulties inherent in long-term rehabilitation and feeding of a leatherback, it was deemed in the animal's best interest to arrange release approximately 48 hours after admission. The animal was released 23.5 miles offshore from St. Petersburg, Florida. Upon release from the boat, she swam in a southerly direction in a normal, controlled fashion. Prior to release, two PIT (Passive Integrated Transponder) tags were implanted within the deltoideus muscle, one in each shoulder. A satellite tracking tag appropriate for monitoring this animal was not available at the time of release, and as no further sightings have been reported for this individual, we cannot state definitively if the rehabilitation was a success. However, this and other recent reports indicate the possibility of successfully holding a leatherback sea turtle in captivity for short periods of time to allow for veterinary diagnostics and emergency care.

Acknowledgments

The authors gratefully acknowledge the advice and assistance of the entire Mote Marine Laboratory community, particularly staff members Charles Froonjian and Joseph Gaspard, volunteer Robert Abrunzo, staff of the Sea Turtle Research and Conservation Program, the Manatee Care and Training Department, and the Sarasota Dolphin Research Program. Many thanks to members of the worldwide sea turtle community for their generous contributions of information and advice at all levels of this endeavor, including Charles Innis, Jeanette Wyneken, Scott Eckert, and Dan Evans. We would also like to express our sincere appreciation to Rhonda Bailey and other members of the Florida Fish and Wildlife Conservation Commission (FWC); Eric Kolek at Sarasota's American Canvas for putting the harness together on very short notice; the captain and crew of Tampa Fire Rescue's Fireboat Patriot for their invaluable assistance with the release; and all of the volunteers and staff who contributed ideas and long hours towards the care and release of this animal.

References

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