Conservation management unit of loggerhead turtles in the North Pacific based on the ecological characteristics of population structure

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H05584
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Conservation of biological resources
• Research Institution: Fisheries Research and Education Agency
• Principal Investigator: OKUYAMA JUNICHI 国立研究開発法人水産研究・教育機構, 西海区水産研究所, 研究員 (80452316)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: ウミガメ / 衛星追跡 / 安定同位体 / バイオロギング / 保全生物学 / 回遊生態 / 回遊多型

Outline of Final Research Achievements

This study approached the mechanism of migration dichotomy (neritic v.s. oceanic) of loggerhead sea turtles (Carretta caretta) nesting in Japan. We conducted the satellite tracking of the turtles nesting at the northern and southern area to figure out which turtles migrate to the neritic/ oceanic habitat. In addition, we analyzed the stable isotope ratios of egg yolk to estimate the ratio of habitat types in each nesting population. Our results indicate that loggerhead turtles nesting at any nesting beaches ordinarily show the migration dichotomy: larger turtles migrate to the neritic foraging area, while smaller migrate to the oceanic foraging area. The ratio of the habitat type demonstrated that almost all of the southern nesting populations were neritic type, meanwhile the ratio of oceanic type gradually increased with the northern populations. This fact indicates that ocean environment around the nesting beach may be involved in the formation mechanism of migration dichotomy.

Free Research Field

保全生態学