Interactions of Oceanographic Factors with Inter-Nesting and Post-Nesting Movements of East Pacific Green Turtles (Chelonia mydas agassizii) from Playa Cabuyal, Guanacaste, Costa Rica

Abstract

Green sea turtles (Chelonia mydas) are long lived migratory species that are found across the globe in tropical waters. In the Eastern Pacific, the green turtles (Chelonia mydas agassizii) remain along the coast and do not venture off the continental shelf. The purpose of this research was to use satellite telemetry to quantify inter-nesting habitats and behavior, post-nesting corridors and foraging ground locations for a population of East Pacific green turtles that nest at Playa Cabuyal, Guanacaste, Costa Rica; and compare these movements to known movements of neighboring populations and local oceanography/topography. Playa Cabuyal is located on the Gulf of Papagayo, which is partially protected under the Santa Rosa National Park. The nesting season for East Pacific green turtles at this site begins in August and continues through April. During a nesting season, each turtle will lay on average 4-6 clutches of eggs at two week intervals. At the end of the nesting season, the turtle will migrate to foraging grounds and remain there for 2-4 years before being ready to nest again. Data collection consisted of two seasons: August-April 2012-2014; and consisted of attaching satellite transmitters to turtles during the nest covering and camouflaging process, post-oviposition. Two types of transmitters were used; MK10 transmitters are attached by tethers and trail behind the turtle, while Spot5 transmitters are epoxied directly onto the shell (Transmitters made by Wildlife Computers Inc). Both transmitter types communicate with overhead satellites every time the turtle comes up for air, allowing us to track their movements over time. We found that during inter-nesting periods, turtles spent most of their time within the gulf of Papagayo. One turtle moved directly off the coast and spent the inter-nesting weeks in slightly deeper water and two other turtles migrated south to the Parque Nacional Las Baulas approximately 50km south. Besides these two different behaviors, eight turtles spent their inter-nesting period within the Gulf. Post-nesting migration behavior was matching: traveling approximately 400km to the Gulf of Fonseca where Nicaragua, El Salvador and Guatemala all meet. This is a foraging ground previously described for neighboring nesting populations of East Pacific green turtles. This tells us that this foraging ground is very important and turtles here are mixing with conspecific turtles from other nesting cohorts. This analysis provides baseline data for future studies on sea turtle movements in the Eastern Pacific, identifies possible coastal foraging locations and migratory routes, and emphasizes that the Gulf of Papagayo is very important for this population, as well as other populations. Management recommendations could include extending the protection of the Santa Rosa National Park to encompass this inter-nesting location. We would like to thank The Leatherback Trust, Indiana University, Purdue University, Community Foundation Sonoma County, and Seeds of Change for making this research possible.http://opus.ipfw.edu/stu_symp2014/1010/thumbnail.jp