Satellite tracking of immature loggerhead turtles in the Northwestern Pacific

Abstract

Five subadult loggerhead turtles (Caretta caretta) captured in the northwestern Pacific in 2002 and 2003 were tracked by satellite telemetry. Two juvenile loggerheads in age of 1+ and 2+ hatched and kept in an Aquarium were also tracked by satellite telemetry in the northwestern Pacific. Five subadult turtles moved at the average speeds of 1.1 to 2.1 km/h with the total distance ranged from approximately 2,200 to 8,800 km during total tracking of 132 to 186 days. The average speeds of 2 juvenile turtles were 2.1 and 1.0 km/h with the total distance of approximately 4,300 and 3,800 km during total tracking of 85 and 156 days, respectively. All subadult turtles moved rapidly the long distance along the Kuroshio Current and its extension and stayed in warm water mass for a long time. The warm water mass might be important feeding grounds of subadult loggerhead turtles. On the other hand, juvenile turtles migrated to higher latitudes than subadult turtles. The difference between subadult and juvenile turtles might result from the difference of feeding grounds by growth stage, body size, ability to swim, or individual career history of turtles.