2018 Fiscal Year Final Research Report
Study on the management of eggs and hatchlings that make use of the hyperactive state of hatchlings, frenzy, after emergence in loggerhead turtles
| Project/Area Number |
16K07232
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Conservation of biological resources
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| Research Institution | Kochi University |
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Principal Investigator |
Saito Tomomi 高知大学, 教育研究部総合科学系複合領域科学部門, 准教授 (80632603)
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| Research Collaborator |
KUMAZAWA Yoshinori
KOBAYASHI Shohei
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 絶滅危惧種 / フレンジー / 生存率 / アカウミガメ / 孵卵 |
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| Outline of Final Research Achievements |
We investigated how the intensity and duration of frenzy swimming in hatchlings changes according to egg incubation conditions in loggerhead turtles. Based on the results, we propose appropriate egg and hatchling management methods. The purpose of this study is to determine loggerhead turtle egg and hatchling management methods that will result in the technical improvement of sea turtle conservation activities.
In this study, it is suggested to extend the incubation period by lowering the temperature below the pivotal temperature of sex determination to increase the body size of hatchlings. Low temperature incubation increases the intensity and persistence of the frenzy and reduces blood glucose concentration in hatchlings because of the influence of the amount of residual egg yolk. As a result, feeding starts earlier and the initial growth rate is high. Hatchlings with high motility and growth rate are considered less likely to be preyed on by predators and have higher survival rates.
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| Free Research Field |
資源保全学
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| Academic Significance and Societal Importance of the Research Achievements |
人工環境下でウミガメの孵卵温度を変化させる事は，幼体の性決定や体サイズに影響を与えたりするほか，本来経験するはずの無かった海洋の水温をも幼体に経験させる事になる．本研究から，遊泳水温が泳力に影響する事に加え，孵卵温度変化が間接的に幼体の生存率に影響する事が示唆された．このような事から，人工環境下におけるウミガメ卵の管理は本種の個体群構造を人為的に攪乱させる可能性があり，その保全は原則として自然孵化によるべきであると考える．しかしながら，やむを得ない事情から卵を保護し，孵卵，育成する場合は，適正な孵卵基質，孵卵温度等の条件を整える事により，絶滅危惧種の資源回復に寄与しうると考えられる．
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