Grant: 15-010R
Project Title: Large Green Turtles of the Marquesas Keys and Surrounding Waters
Project Manager: Michael Bresette
Organization: Inwater Research Group (Non-Profit Organization)
Grant Amount: $18,426.25
Completion Date: 2020-02-24

Summary: In the course of ongoing work in the Key West National Wildlife Refuge, Inwater Research Group (IRG) has identified areas adjacent to the refuge near the Marquesas Keys where high densities of sub-adult and adult green turtles can be observed. This area is the only known foraging ground for greens turtles in these size classes and numbers in the southeastern United States where empirical data exist. These foraging grounds are located in a remote area that previously have only been accessed in optimal weather conditions. This past summer while using a recently acquired vessel better suited for accessing the remote foraging ground, IRG was able to perform both visual surveys and rodeo captures for the first time since 2010. Inwater Research Group will continue a focused research effort involving vessel based surveys and rodeo captures to document the geographical extent of these unique foraging grounds and to collect data on size class distribution, growth rate, prevalence of disease, sex ratio and genetic origin of the green turtle aggregation found within.

Results: Two sampling trips west of the Marquesas Keys were conducted during this report period. During four days between August 20 and 23, 2015 we completed the first sampling event at the green turtle foraging grounds west of the Marquesas. With support from the National Save a Sea Turtle Foundation we kept the RV Hawksbill at the study site and used it as a mothership. During this four day sampling trip we captured 15 large green turtles ranging in size from 55.7 Ė 103.2 cm SCL. These turtles consisted of 1 juvenile, 5 sub adults and 9 adults (6 females and 3 males). Our second sampling trip was conducted between September 17 and 22, 2015. During this six day sampling effort we captured 4 large green turtles ranging in size from 73.5 Ė 91.5 cm SCL at the Eastern Quicksands site. On this second sampling trip weather conditions and water visibility hampered our capture efforts at the Eastern Quicksands study site. When these conditions were present we worked other areas in the Key West National Wildlife Refuge. We captured a total of 30 sea turtles during the two sampling trips in 2015, including 22 green turtles, 7 loggerheads and 1 hawksbill. All turtles were measured, tagged and photographed before release and blood/tissue samples were collected for genetics and sex determinations. A majority of our capture effort focused on the foraging grounds west of the Marquesas Keys where we captured a total of 19 large green turtles that ranged from 55.7 Ė 103.2 cm straight carapace length (SCL, mean=86.4, SD=13.0). Of the green turtles captured on the foraging grounds 8 were females, 4 were males and 7 were sub-adults with undetermined gender. Captures in the refuge also included 7 loggerheads ranging from 67.0 Ė 92.2 cm SCL (mean=80.0, SD=10.6), 3 green turtles ranging from 44.6 Ė 54.6 cm SCL (mean=50.4, SD=5.2) and one hawksbill (27.3 cm SCL). In 2015, we recaptured four loggerheads we had tagged on previous sampling trips. One of the loggerheads was originally tagged at the St. Lucie power plant on 10/6/2006 and captured in the refuge on 10/18/2011 and again during 2015. One of the adult female green turtles captured at the Eastern Quicksands site had originally been tagged by other researchers on a nesting beach in the Pacuare Preserve in Costa Rica. We are still waiting for the original tagging information for this turtle. Genetic and sex determination samples from all turtles captured in 2015 are currently being processed and the results from those analysis will be presented in our final report to the STGP. Visual transects conducted during this report period included our HUNTís, fixed repeatable grid transects and snorkel transects. During our HUNTís we observed 58 green turtles and 11 loggerheads over 44.2 km of transects for a sightings per unit effort (SPUE) of 1.56 sea turtles per km of transect. We conducted our fixed transect grid over the foraging ground twice in 2015. The grid consists of six, six km long transects for a total of 36 km of transects over the foraging ground. We observed 141 green turtles, two loggerheads and two hawksbills while conducting 72 km of transects on the grid. The SPUE for the Eastern Quicksands was 2.01 sea turtles per km of transect. We also conducted 6.65 kilometers of snorkel transects in the KWNWR at the West Jetty site. During these transects we observed two green turtles, one adult Kempís ridley and one hawksbill for a SPUE of 0.60 sea turtles per km of transect. The adult Kempís ridley was the first ever observed in the refuge by our group since the beginning of this study in 2002.