HATCHLING TRANSPORT OF LOGGERHEAD TURTLES IN THE NORTH PACIFIC

Abstract

Using an advection and diffusion model for particle tracking in three dimensions, the hatchling transport process of loggerhead, Caretta caretta and green turtles, Chelonia mydas in the North Pacific was investigated. Loggerhead hatchlings were transported eastward to northeastward by the Kuroshio from their nest, Yakushima Island, and were transported 2770 km on average over 60 days (46 km/d). These indicate that the Kuroshio enables loggerhead hatchings and juveniles to spread out without them using up their energy. In addition, transported by the Kuroshio provides them with a significantly lower mean ambient water temperature (20.7±4.1℃) than that around the nest (24.0±0.5℃). In contrast, green turtle hatchlings were transported northwestward from their nest, the Ogasarawa islands, and their mean location after 60 days was no more than 323 km away from their nest. The mean ambient water temperature during transport showed little difference from that around the nesting islands (24.5℃). These suggest that their thermal condition relatively stable in their early life in comparison with loggerhead turtles.