Movements and behavior of the East Pacific Green Turtle (Chelonia mydas) from Costa Rica

I attached satellite transmitters to study the movements and behavior during internesting and migration of East Pacific green turtles nesting on Nombre de Jesús and Zapotillal. Prior to transmitter attachment we preformed an ultrasound scan to determine the turtle’s reproductive status. I obtained information on geostrophic surface currents to simulate the dispersion of hatchlings emerging from Nombre de Jesús. I determined the Estimated clutch frequency (ECFU: mean ± SD) 5.13 ± 1.32 using ultrasound, which was an effective technique to determine the reproductive effort of turtles. Turtles spent the 12 day internesting period in the nearby waters off the nesting beach using mainly an area of 4.5 km2. Depths of dives and depth of water in the area indicated that the turtles dove to the bottom to rest during the day and rested at the surface during the night. After the nesting season, some turtles moved to their foraging areas in Gulf of Papagayo and the Santa Elena Bay, close to the Gulf of Fonseca, and in inshore waters of Panama. During migration the turtles dove mainly to a depth of 5 m or less. During foraging most of the dives were between 5 and 10 m depth. I found three different scenarios for possible hatchling dispersion: 1-hatchlings could be transported offshore and after three months pushed back closer to the coast, 2- hatchlings could be transported north or south remaining along the coast and, 3-hatchlings could be transported to waters offshore still within the Eastern Tropical Pacific (ETP). East Pacific green turtles remained their entire life within the waters of the ETP including females, which carry out limited to-long-distance migrations (5 to 1091 km). The unique characteristics of the area disperse hatchlings to productive areas providing them with enough resources to grow at the early life stages and move to adult foraging areas also in the ETP. The coastal nature of their movements and the high concentration of turtles off the nesting beach make them vulnerable to artisanal fisheries. That, together with intense poaching that occurs on the nesting beach indicates that this population may soon face extinction.Ph.D., Ecology -- Drexel University, 201