POST-NESTING MOVEMENTS AND HIGH USE INTERNESTING AREAS FOR EAST PACIFIC GREEN TURTLES NESTING IN COSTA RICA

GABRIELA S. BLANCO; STEPHEN J. MORREALE; JEFFREY A. SEMINOFF; ROTNEY PIEDRA; FRANK V. PALADINO; JAMES R. SPOTILA

San Diego, California, USA

Simposio; 31st Annual Symposium on Sea Turtle Biology and Conservation; 2011

International Sea Turte Siciety

We attached hydrodynamic satellite transmitters by tether to 13 East Pacific green turtles (Chelonia mydas) during their internesting and to 10 green turtles after their last nesting event. The goal of this study was to identify high use internesting areas and migration routes of green turtles nesting on Nombre de Jesús and Zapotillal in the Pacific Coast of Costa Rica, and to determine areas in need of protection. During internesting a fixed Kernel density analysis showed that high use areas were particularly close to the nesting beaches; utilization distribution polygons of 50% and 95% included 4.5 km2 and 53.9 km2, respectively. The post nesting migrations were characterized by coastal movements ranging from 5-1091 km. Two turtles were local residents in the Gulf of Papagayo in Costa Rica; four moved an intermediate distance to the South of Nicaragua, one turtle moved to Panama, two moved to the Gulf of Fonseca in Nicaragua and Honduras and one moved to El Salvador. The high concentration of nesting turtles and the lack of long-distance movements during the internesting period underscores the extensive use of the vicinities of the nesting beach by resting turtles. The restricted range of movements during internesting indicates that the waters off Nombre de Jesús are of great importance for East Pacific green turtles, and likely a crucial location for conservation of this population. Our study also suggests that some green turtles nesting in Nombre de Jesus and Zapotillal may spend all their life as adults along the coast of Central America. Those beaches are of great importance because they help to sustain the East Pacific green turtle population in Central America. Also, there is a resident subpopulation, where nesting occurs on Nombre de Jesús and foraging occurs in the Gulf of Papagayo, those being only 5 km apart, emphasizing the importance of Costa Rica for the conservation of this population. The coastal nature of their movements makes them vulnerable to human activities. The fact that the turtles are swimming through different countries makes management more complex and call for conservation agreements between nations.