Post-nesting habitat selection by female loggerhead turtles Carreta caretta in Japan

Abstract

Abstract The number of nests of loggerhead turtle Carreta caretta in Japan has been declining in recent years and needs to be protected. Loggerheads spending most of time in foraging areas, it is important for their conservation to investigate their habitat and the environmental features that affect their habitat selection. During 2018 and 2019 nesting seasons, 23 nesting females were attached satellite transmitters at Tanegashima Island where is one of the largest nesting sites in Japan and tracked their post-nesting migration. Most inhabited the East China Sea (ECS) and Tsushima Strait, using three narrow areas in summer and moving to broader area in winter. Environmental factors and body size that may influence loggerhead’s habitat selections were compared for each highly used area and entire home range. Summer areas had relatively slower current compared to the surrounding. Wintering areas had faster currents but temperate. Primary productivity has not affected their habitat selection. Loggerheads using the most northern area were the largest of the three summer areas. Loggerheads select habitats in the ECS and Tsushima Strait that enable them to conserve their energy consumption, and that have comfortable temperatures. This result would be worth establishing their conservation measure.