IMIS

The oceanic movements of a captive-raised adult loggerhead turtle (Caretta caretta) were monitored with satellite telemetry for 368 days from 10 August 1996 to 12 August 1997. During this time, the turtle migrated across the Pacific Ocean, covering more than 11,500 km between Santa Rosalita, Baja California, Mexico (28 degrees 40 minutes N, 114 degrees 14 minutes W), and Sendai Bay, Japan (37 degrees 54 minutes N, 140 degrees 56 minutes E). The average speed during migration was 1.3 km/h and the maximum recorded speed was 1.84 km/h. These findings are consistent with the hypothesis that loggerheads feeding in the eastern Pacific eventually return to nest on western Pacific beaches. Baja California loggerhead turtles have been shown, through molecular genetic analysis and flipper tag returns, to be primarily of Japanese origin. We conclude that loggerhead turtles are capable of transpacific migrations and propose that the band of water between 25 and 30 degrees North latitude, the Subtropical Frontal Zone, may be an important transpacific migratory corridor. Recent findings indicate that juvenile loggerheads in the North Pacific move westward against weak (0.1-0.3 km/hr) eastward geostrophic currents, demonstrating that passive drift may not entirely explain the dispersal of loggerheads.