2018 Fiscal Year Final Research Report
Population dynamics mechanism on the Japanese eel in natural river based on physiological and ecological analyses
| Project/Area Number |
16K07851
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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 |
Aquatic bioproduction science
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| Research Institution | Kitasato University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | ニホンウナギ / 接岸生態 / 塩分適応 / グリコーゲン |
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| Outline of Final Research Achievements |
To contribute to recovery of the stock of the Japanese eel, monitoring of the recruitment pattern and development of the method to quantitatively measure the quality of the glass eels were carried out. Recruitment was observed in late December to early April, and summer recruitment was confirmed to occur in almost every each year. Relative area of the chloride cells were at constant throughout the recruitment period, but were largely varied in the simultaneously recruited populations, suggesting that such individual variability cause flexible migration pattern in this species. Glycogen contents decreased at the late of the recruitment period, and is considered to be useful index to quantify the glass eels recruited.
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| Free Research Field |
個体群生態学
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| Academic Significance and Societal Importance of the Research Achievements |
水産重要種であるニホンウナギの資源は激減しており，早急な保全策の立案が求められている．しかしシラスウナギの漁獲量は信頼度に劣り，資源の動態を把握する上での障害となっている．本研究は科学的な手法で接岸モニタリングを実施し，天然加入が期待される初夏の来遊が2年に一度ほどの頻度で起こることを明らかにした．また，海水から淡水に成長の場を移す際に重要な塩類細胞の大きさには個体差があり，これによりニホンウナギは幅広い塩分環境を利用する可能性を見出した．さらに，生存に重要なグリコーゲン量は接岸時期の終盤にかけて低下することを明らかにし，天然加入と養殖用に使い分けるための質の指標としての有用性を見出した．
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