| Project/Area Number |
08456094
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TUKAMOTO Katsumi The University of Tokyo, Ocean Research Institution, Professor, 海洋研究所, 教授 (10090474)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIDA Mutsumi Fukui Prefectural University, Faculty of Biotechnology, Professor, 生物資源学部, 教授 (90136896)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 1997: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1996: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Keywords | eel / inshore migration / mtDNA / control region / population analysis / oltolith / daily ring / metamorphose / 調節領域 |
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| Research Abstract |
Mechanism of inshore migration of the Japanese eel was studied as follows :
1. Age determination and estimation of migratory history
Age at recruitment of the glass eel to East Asian coasts was 143-206 days after hatching. It was revealed that the younger individuals with the higher growth rate migrated to rivers at the lower latitudes. Analysis of otolith Sr/Ca ratio by EPMA showed that the leptocephali would begin to metamorphose at mean age of 130 d (range : 80-160 d) and it last for about 30 d (20-40 d).
2. Population structure
Comparing 500bp sequences of 16SrRNA cording region on mtDNA enabled to identify all 18 species of genus Anguilla, even if the samples would be eggs or small leptocephali which could not be identified with morphological features. A part of the mitochomdrial control region of 47 Anguilla japonica collected from Ibaragi, Kanagawa and Kagoshima prefecture in Japan were determined and showed that all individuals belong to one reproductive population. Furthre analysis including the previously reported 31 sequence data of A.japonica collected from Taiwan, Korea and China suggested a single mating population for this species. Thus, stock management of A.japonica should be performed not only within Japan but among all the East Asian countries.
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