Study on the reproductive ecology of the endangered loggerhead sea turtle on the Shikoku coast

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The nesting of loggerhead turtle was observed forty eight times on the coast near Niyodo River mouth, Tosa Bay, from the middle of May to the end of July in 2013 and showed the maximum frequency among the entire nesting sites of Kochi prefecture during 2013. Of the location of survey that covered 3.4 km, an area that stretched 0.9 km near the east of the river mouth featured such suitable factors of environment for nesting and indicated the utmost nesting success rate of 92.6 %.Six turtles were caught off Tosa Bay from the middle of November in 2013 to the end of January in 2014. Those were identified as three females and three males by the sex hormone density. Among them one female and one male were matured but the rest were determined to be immature. From here onwards, it was revealed that Tosa Bay would allow adult and sub-adult turtles to migrate even in winter seasons and would be one of the important water-zones for reproduction of loggerhead turtles.