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
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Conservation of biological resources
• Research Institution: Kochi University
• 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)
• Research Collaborator: KUMAZAWA Yoshinori ; KOBAYASHI Shohei
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
• Keywords: 絶滅危惧種 / フレンジー / 生存率 / アカウミガメ / 孵卵 / 資源保全学 / 動物生態学 / 生残率 / 繁殖生態 / 保全 / 資源管理 / 保全生物 / 生活史

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.

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．

Research Products

• [Journal Article] Effects of sand type on hatch, emergence, and locomotor performance in loggerhead turtle hatchlings (2019)
  • Author(s): Saito Tomomi、Wada Maoko、Fujimoto Ryohei、Kobayashi Shohei、Kumazawa Yoshinori
  • Journal Title: Journal of Experimental Marine Biology and Ecology Volume: 511 Pages: 54-59
  • DOI: 10.1016/j.jembe.2018.10.008
  • Peer Reviewed
• [Journal Article] 高知県におけるアカウミガメの産卵海岸選択に影響する環境要因 (2019)
  • Author(s): 小林陽介、藤本竜平、小坂將、三宅香成、田中幸記、斉藤知己
  • Journal Title: 黒潮圏科学 Volume: 12(2) Pages: 156-173
  • NAID: 120006628944
  • Peer Reviewed / Open Access
• [Journal Article] Incubation and water temperatures influence the performances of loggerhead sea turtle hatchlings during the dispersal phase. (2018)
  • Author(s): Kobayashi, S, Aokura, N, Fujimoto, R, Mori, Kumazawa, Y, Ando, Y, Matsuda, T, Nitto, H, Arai, K, Watanabe G.
  • Journal Title: SCIENTIFIC REPORTS Volume: 8 Issue: 1 Pages: 1-8
  • DOI: 10.1038/s41598-018-30347-3
  • Peer Reviewed / Open Access
• [Journal Article] アカウミガメ孵化幼体の遊泳活性の経時変化 (2018)
  • Author(s): 藤本竜平・和田真央子・小林翔平・熊澤佳範・斉藤知己
  • Journal Title: 黒潮圏科学 Volume: 11 Pages: 152-162
  • NAID: 120006487140
  • Peer Reviewed / Open Access
• [Journal Article] 高知県下の砂浜海岸におけるスナガニ類（スナガニ属、スナガニ亜科、スナガニ科、短尾亜目）の出現 (2018)
  • Author(s): 髙木真成・藤本竜平・早稲田沙織・斉藤知己
  • Journal Title: 黒潮圏科学 Volume: 11 Pages: 128-139
  • NAID: 120006487137
  • Peer Reviewed / Open Access
• [Journal Article] The effects of nest incubation temperature on embryos and hatchlings of the loggerhead sea turtle: Implications of sex difference for survival rates during early life stages (2017)
  • Author(s): Kobayashi, S., Wada，M., Fujimoto, R., Kumazawa, Y., Arai, K., Watanabe, G., Saito, T.
  • Journal Title: Journal of Experimental Marine Biology and Ecology Volume: 486 Pages: 274-281
  • Peer Reviewed
• [Journal Article] 高知県仁淀川河口浜（新居・仁ノ海岸）におけるアカウミガメの産卵生態および産卵場所の砂の粒径について (2017)
  • Author(s): 和田真央子，藤本竜平，大山淳也，小林翔平，熊澤佳範，斉藤知己
  • Journal Title: 黒潮圏科学 Volume: 10(2) Pages: 136-147
  • NAID: 120006227604
  • Peer Reviewed
• [Presentation] Incubation temperatures influence the sex differences in the survival of loggerhead sea turtle during early life stages (2018)
  • Author(s): Shohei Kobayashi, Ryohei Fujimoto, Yoshinori Kumazawa, Katsuhiko Arai, Gen Watanabe, Tomomi Saito
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research
• [Presentation] Temporal changes in, and influence of storage conditions on, the frenzy swimming activity of loggerhead turtle hatchlings (2018)
  • Author(s): Fujimoto, R., Kosaka, S., Miyake, K., Kobayashi, Y., Kumazawa, Y., Saito, T.
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research
• [Presentation] Effects of emergence on loggerhead turtle hatchlings (2018)
  • Author(s): Kosaka, S., Fujimoto, R., Kobayashi, Y., Miyake, K., Kobayashi, S., Kumazawa, Y., Saito, T.
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research
• [Presentation] Effect of incubation temperature fluctuation on loggerhead turtle hatchlings (2018)
  • Author(s): Miyake, K., Fujimoto, R., Kosaka, S., Kobayashi, Y., Kobayashi, S., Kumazawa, Y., Saito, T.
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research
• [Presentation] Environmental factors influencing loggerhead turtle nesting on sandy beaches in Kochi Prefecture (2018)
  • Author(s): Kobayashi, Y., Fujimoto, R., Miyake, K., Kosaka, S., Tanaka, K., Saito, T.
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research
• [Presentation] A new approach toward sea turtle conservation: relocation of eggs from a captive breeding program to a natural beach (2018)
  • Author(s): Ando, Y., Matsuda, T., Okamoto, H., Kobayashi, K., Kasugai, T., Kurita, M., Nitto, H., Saito, T., Tanaka, Y., Imamura, K.
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research
• [Presentation] Ships of opportunity: releasing satellite-tagged little loggerheads on the high-seas to study their pelagic ecology (2018)
  • Author(s): George H. Balazs, Marc Rice, Denise Parker, Tomomi Saito, Richard Farman
  • Organizer: ISTS 38th Annual Symposium on Sea Turtle Biology and Conservation, Kobe, JAPAN
  • Int'l Joint Research / Invited
• [Presentation] アカウミガメにおける孵卵温度の日内変動の影響について (2018)
  • Author(s): 三宅香成・高田光紀・向後蓮太郎・芦田泉香子・小坂將・小林翔平・熊沢佳範・斉藤知己
  • Organizer: 第57回日本爬虫両棲類学会大会
• [Presentation] 脱出過程がアカウミガメの孵化幼体に与える影響について (2018)
  • Author(s): 小坂將・芦田泉香子・向後蓮太郎・高田光紀・三宅香成・小林翔平・熊沢佳範・斉藤知己
  • Organizer: 第57回日本爬虫両棲類学会大会
• [Presentation] 孵卵温度の日内変動がアカウミガメ孵化幼体の形態、運動性、成長率に与える影響について (2018)
  • Author(s): 三宅香成・高田光紀・向後蓮太郎・芦田泉香子・小坂 將・小林翔平・熊沢佳範・斉藤知己
  • Organizer: 第29回日本ウミガメ会議（与論島大会）
• [Presentation] 脱出過程がアカウミガメの孵化幼体の形態と運動性に与える影響について (2018)
  • Author(s): 小坂將・向後蓮太郎・芦田泉香子・高田光紀・三宅香成・小林翔平・熊沢佳範・斉藤知己
  • Organizer: 第29回日本ウミガメ会議（与論島大会）
• [Presentation] タイマイにおける孵卵温度の日内変動の影響について (2018)
  • Author(s): 高田光紀・三宅香成・小坂將・向後蓮太郎・芦田泉香子・河津勲・深田晋吾・小淵貴洋・真栄田賢・徳武浩司・斉藤知己
  • Organizer: 第29回日本ウミガメ会議（与論島大会）
• [Presentation] アカウミガメ孵化幼体の脱出行動発現の機構について (2018)
  • Author(s): 向後蓮太郎・芦田泉香子・小坂將・高田光紀・三宅香成・熊沢佳範・斉藤知己
  • Organizer: 第29回日本ウミガメ会議（与論島大会）
• [Presentation] アカウミガメ孵化幼体の孵化後の運動性と代謝について (2018)
  • Author(s): 芦田泉香子・向後蓮太郎・小坂將・高田光紀・三宅香成・小林翔平・熊沢佳範・斉藤知己
  • Organizer: 第29回日本ウミガメ会議（与論島大会）
• [Presentation] Incubation temperatures influence the sex differences in the survival of loggerhead sea turtle during early life stages (2018)
  • Author(s): Shohei Kobayashi, Ryohei Fujimoto, Yoshinori Kumazawa, Katsuhiko Arai, Gen Watanabe, Tomomi Saito
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research
• [Presentation] Temporal changes in, and influence of storage conditions on, the frenzy swimming activity of loggerhead turtle hatchlings (2018)
  • Author(s): Ryohei Fujimoto, Sho Kosaka, Yosuke Kobayashi, Kanari Miyake, Yoshinori Kumazawa, Tomomi Saito
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research
• [Presentation] Effect of incubation temperature fluctuation on loggerhead turtle hatchlings (2018)
  • Author(s): Kanari Miyake, Ryohei Fujimoto, Sho Kosaka, Yosuke Kobayashi, Shohei Kobayashi, Yoshinori Kumazawa, Tomomi Saito
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research
• [Presentation] Effects of emergence on loggerhead turtle hatchlings (2018)
  • Author(s): Sho Kosaka, Ryohei Fujimoto, Yosuke Kobayashi, Kanari Miyake, Shohei Kobayashi, Yoshinori Kumazawa, Tomomi Saito
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research
• [Presentation] Environmental factors influencing loggerhead turtle nesting on sandy beaches in Kochi Prefecture (2018)
  • Author(s): Yosuke Kobayashi, Ryohei Fujimoto, Kanari Miyake, Sho Kosaka, Kohki Tanaka, Tomomi SaitoT.
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research
• [Presentation] A new approach toward sea turtle conservation: relocation of eggs from a captive breeding program to a natural beach (2018)
  • Author(s): Yusuke Ando, Tsuyoshi Matsuda, Hitoshi Okamoto, Kiyoshige Kobayashi, Takashi Kasugai, Masanori Kurita, Hiroshi Nitto, Tomomi Saito, Yuji Tanaka, Kazushi Imamura
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research
• [Presentation] Ships of opportunity: releasing satellite-tagged little loggerheads on the high-seas to study their pelagic ecology (2018)
  • Author(s): George H. Balazs, Marc Rice, Denise Parker, Tomomi Saito, Richard Farman
  • Organizer: International Sea Turtle Society 2018 Annual Symposium on Sea Turtle Biology and Conservation
  • Int'l Joint Research / Invited
• [Presentation] 孵卵温度がアカウミガメの幼体の成長率に与える影響 (2017)
  • Author(s): 森啓輔，小林翔平，藤本竜平，青倉七雲，熊澤佳範，斉藤知己
  • Organizer: 第44回四国魚類研究会
  • Place of Presentation: 土佐市竜・三陽荘
  • Year and Date: 2017-03-04
• [Presentation] 孵卵温度および遊泳水温がアカウミガメ孵化幼体のフレンジーに与える影響について (2017)
  • Author(s): 青倉七雲，藤本竜平，森啓輔，小林翔平，熊澤佳範，斉藤知己
  • Organizer: 第44回四国魚類研究会
  • Place of Presentation: 土佐市竜・三陽荘
  • Year and Date: 2017-03-04
• [Presentation] ウミガメ類の子ガメのフレンジー（運動活性の著しく高い状態）を計測する (2017)
  • Author(s): 藤本竜平，斉藤知己
  • Organizer: ふるさとの いのちをつなぐ～豊かな生きものの恵みを受けて 美味しく 楽しく ずっと暮らそう高知県
  • Place of Presentation: 須崎市立市民文化会館
  • Year and Date: 2017-02-19
• [Presentation] アカウミガメ孵化幼体の遊泳活性の経時変化および保管条件による影響 (2017)
  • Author(s): 藤本竜平・小坂將・小林陽介・三宅香成・熊沢佳範・斉藤知己
  • Organizer: 第56回日本爬虫両棲類学会
• [Presentation] 仁淀川河口海岸におけるアカウミガメの産卵成功率および砂の粒径が卵と孵化幼体に与える影響について (2017)
  • Author(s): 和田真央子・藤本竜平・小林翔平・熊澤佳範・斉藤知己
  • Organizer: 第56回日本爬虫両棲類学会
• [Presentation] 孵卵温度がアカウミガメの幼体の成長率に与える影響 (2016)
  • Author(s): 森啓輔，小林翔平，藤本竜平，青倉七雲，熊澤佳範，安藤友佑，松田乾，日登弘，斉藤知己
  • Organizer: 第27回日本ウミガメ会議（室戸会議）
  • Place of Presentation: 室戸市保健福祉センターやすらぎ
  • Year and Date: 2016-12-09
• [Presentation] 高知大学海洋生物研究教育施設によるウミガメ保護にかかる調査研究の取り組み (2016)
  • Author(s): 藤本竜平，斉藤知己，熊沢佳範
  • Organizer: 第27回日本ウミガメ会議（室戸会議）
  • Place of Presentation: 室戸市保健福祉センターやすらぎ
  • Year and Date: 2016-12-09
  • Invited
• [Presentation] 孵卵温度および遊泳水温がアカウミガメ孵化幼体のフレンジーに与える影響について (2016)
  • Author(s): 青倉七雲，藤本竜平，森啓輔，小林翔平，熊澤佳範，安藤友佑，松田乾，日登弘，斉藤知己
  • Organizer: 第27回日本ウミガメ会議（室戸会議）
  • Place of Presentation: 室戸市保健福祉センターやすらぎ
  • Year and Date: 2016-12-09
• [Presentation] Effects of sand particle size on hatching, emergence and locomotor performance of loggerhead turtle hatchlings (2016)
  • Author(s): Maoko Wada, Ryohei Fujimoto, Shohei Kobayashi, Yoshinori Kumazawa, Tomomi Saito
  • Organizer: The 22nd International Congress of Zoology, the 87th Meeting of the Zoological Society of Japan, Joint Events in Okinawa, Japan
  • Place of Presentation: Okinawa Convention Center
  • Year and Date: 2016-11-15
  • Int'l Joint Research
• [Remarks] 高知大学研究者総覧
  • URL: http://www.jimu.kochi-u.ac.jp/~soran/sansyo.asp?ID=2206