| Project/Area Number |
60560194
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MOCHIZUKI Kenji Univ. Mus., Univ. of Tokyo, Research Associate, 国立大学(その他), 助手 (50114682)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Plecoglossus altivelis / Structure of Population / Survival / Morphology / Formation of Borns / 日令 |
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| Research Abstract |
The present study intend to discriminate population of ayu-fish, Plecoglossus altivelis, originated from the Lake Biwa population which was released in rivers from Japanese river populations of the fish , and then to examine structure of populations in coastal waters. At first I examined morphologically larvae and juveniles of the two populations which were reared under similar conditions to find any differences that the two were discriminated from each other. Comparison of 15 morphological characters between the two shows that they are different from each other in 9 characters , but the results could not show which population each individual was belonged to. I collected larvae and juveniles in the sea near Kumano River, and morphological characters of them were compared with those of the reared populations. I could not find any differences morphologically between the wild and the reared river populations, but the wild was different from the reared Lake Biwa population in three characters. The results may imply that many of the wild samples were belonged to river population. Size of the reared river samples when formation of most cartilages and bones of them were started is bigger than that of the reared Biwa Lake samples. Examination of daily-ring of the wild samples shows existence of some individuals which were hatched in the middle-late September though number of them were few. The date were corresponded to those of fishes originated the Biwa Lake population. Therefore the present results imply that fishes originated the Biwa Lake population are able to survive in sea waters, and fishes originated from the Biwa Lake population should be discriminated from the river population in biological studies. The present study will be progressed to examine structure of wild population in seas based on the results mentioned above.
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