2023 Fiscal Year Final Research Report

Interplay between nutrition and reproduction in the neuroendocrine network of fish under tropical monsoon environments

Research Project

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Project/Area Number	20KK0143
Research Category	Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
Research Institution	University of the Ryukyus
Principal Investigator	Takemura Akihiro 琉球大学, 理学部, 教授 (40222103)
Co-Investigator(Kenkyū-buntansha)	山内千裕琉球大学, 理学部, 技術補佐員 (20888664) 武方宏樹琉球大学, 戦略的研究プロジェクトセンター, 特命助教 (60814192) 野津了一般財団法人沖縄美ら島財団(総合研究センター), 総合研究センター動物研究室, 主任研究員 (70774397)
Project Period (FY)	2020-10-27 – 2024-03-31
Keywords	モンスーン / ベトナム / 降雨 / 日長 / メラトニン
Outline of Final Research Achievements	The objective of this study was to clarify the factors that synchronize fish reproductive activities. Attention was paid to the primary production in the sea and the nutritional improvement of fish due to rainfall changes linked to the monsoon. We monitored environmental changes and fish reproductive activities in a shallow-water area near Hue in central Vietnam. We also conducted the experiments to clarify the relationship between environmental factors and fish reproductive activity. It was found that primary production in the sea area increased during the rainy season. It was revealed that nutritional conditions in fish are important for reproductive activity and that melatonin affects the expression of insulin-like growth factors via growth hormone and thyroid hormone. In addition to changes in photoperiod, fish adapted to the monsoon may utilize changes in monsoon-involved primary production in the sea area for synchrony of their activities.
Free Research Field	水産生物学
Academic Significance and Societal Importance of the Research Achievements	本研究は魚類の繁殖活動の時刻合わせが生息海域の環境変動と密接に関係していることを明らかにした。光や温度の変化に加えて、熱帯・亜熱帯域における変動要因であるモンスーンに起因する海域の一次生産量が魚の栄養状態に影響を与え、繁殖活動が変化することを示した。これらの結果は、熱帯・亜熱帯域の魚類の繁殖活動を人為的に操作する基礎資料となり、熱帯・亜熱帯域で活発になっている養殖技術改良に資する。