Grant: 14-030R
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: 2015-09-25
Summary: In the course of ongoing work in the Key West National Wildlife Refuge, Inwater Research Group (IRG) has identified areas adjacent to of 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 grounds for greens turtles of these size classes in the southeastern United States where empirical data exist. These foraging grounds are located in a remote area and previously have only been accessed in optimal weather conditions. Recent upgrades to IRG's fleet will allow for more frequent access to these foraging grounds. IRG will collaborate with NOAA to use Unmanned Aerial Vehicles (UAV) to conduct established, repeatable transects over the foraging grounds using high resolution cameras. These transects will be flown below 150 meters altitude. The UAVs will also be used to identify sea grass coverage on the foraging grounds and scout new areas adjacent to the foraging grounds that have not previously been surveyed. IRG will also implement 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 populations found within.
Results: During the July sampling trip we conducted 106.3 km of visual transects in the Marquesas region of the Key West National Wildlife Refuge, including 36 kilometers of our fixed grid west of the Marquesas Keys. We observed 30 green turtles (17 adults, 11 sub-adults and 2 juveniles) on transects conducted on the foraging grounds west of the Marquesas Keys. We captured a total of 20 sea turtles during the sampling trip in July 2015, including 14 green turtles, 5 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. In collaboration with personnel from the Florida Keys National Marine Sanctuary (FKNMS) visual transects were conducted using their PUMA fixed wing UAS on March 10-13, 2015. This project was established to determine the effectiveness of using a UAS to observe sea turtles from video images of flight transects in the Marquesas and surrounding waters. Five flights were conducted totaling 41.96 kilometers. Two flights were conducted over the foraging grounds west of the Marquesas Keys totaling 8.6 kilometers and three flights covering 33.2 kilometers were flown over Barracouta Key. Test flights were flown at an elevation of 100 feet and 300 feet. No turtles were positively identified on any of the UAS flights. The weather during this sampling trip was challenging with 20-30 mph winds and 2-3 foot seas within the refuge and 3-5 foot seas at the foraging grounds west of the Marquesas. Because of sea conditions and wind only two flights were conducted over the foraging grounds.