Project Title: A Preliminary Assessment of Hawksbill Sea Turtles (Eretmochelys imbricata) in Palm Beach County Waters
Project Manager: Lawrence Wood
Organization: Loggerhead Marinelife Center (Non-Profit Organization)
Grant Amount: $8,483.00
Completion Date: 2007-05-18
Summary: This study continues to focus on the size composition, genetic identity, seasonality, site fidelity, and growth rates of Critically Endangered hawksbill turtles in Florida coral reef habitats that was begun in 2004. Turtles will be hand-captured during SCUBA dives along the Breakers Reef chain of coral reefs along Palm Beach County. Methods will include both traditional tagging of all captured animals with inconel and PIT tags, and painting of numbers on the shells of a limited number of individuals for continual documentation by recreational divers. Tissue samples will also be collected for genetic analyses. Also, the feasibility of photographic identification through unique individual characteristics will be tested by referencing the newly tagged turtles against an extensive photographic library that has been compiled by local underwater photographers over many years. If unique identifying features are found, a photographic database of known turtles will be created and updated as new data are gathered. The funding requested is for equipment, dive boat fees, personnel costs involved in the capture of the turtles, and laboratory fees.
Results: To date, 27 tagged hawksbills have been seen and reported by divers, some repeatedly, totaling well over 100 re-sighting reports. The longest records of individual turtles exceed two and a half years. Of note is that the sightings are not seasonal, many of the turtles appear to be residents year-round even with sub-tropical seasonal water temperature variations that vary by as much as 20 degrees fahrenheit. Another interesting feature of the re-sighting data is that many of the turtles are repeatedly seen in close proximity to the original capture site, suggesting a relatively small home range for each turtle that overlaps with those of other individuals. Others have been seen repeatedly on the same set of wrecks, and as of yet, nowhere else. Of course, we do not know what the turtle may have done between sightings, however it is important to note that no reports of tagged turtles have been received from outside the study area, while many have been received from within it. We look forward to utilizing remote sensing technology in the next year or two, perhaps GPS transmitters, to examine movement patterns in more detail. The results of the mtDNA analyses suggest that the majority of the hawksbills in Palm Beach County originate in Mexico, however a total of seven haplotypes have been identified, one from as far away as Costa Rica. These results suggest that there is some contribution to this population from a variety of Caribbean stocks. (Author: Larry Wood)