| Project/Area Number |
06660237
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
KINOSHITA Izumi Kyoto Univ., Fac.of Agr., Assis.Prof., 農学部, 助手 (60225000)
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| Co-Investigator(Kenkyū-buntansha) |
SEIKAI Tadahisa Kyoto Univ., Fac.of Agr., Assis.Prof., 農学部, 助手 (10144338)
TANAKA Masaru Kyoto Univ., Fac.of Agr., Prof., 農学部, 教授 (20155170)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1995: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Estuary / Shimanto River / Brackish waters / Larval fishes / Nusery / Reproduction / アユ / 両側回遊魚 / 鉛直分布 / プロラクチン / 淡水適応 |
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| Research Abstract |
The larval and juvenile ichthyofauna of the shimanto estuary and adjacent surf zones showed marked differences from that of the coastal and offshore habitats in the poorness of Engraulis japonicus, which occurs in those habitats as by far the dominant species. The presence of Mugil cephalus, Liza carinata, Terapon jarbua and Acanthopagrus schlegeli and the absence of Blenniidaem, Sebasticus marmoratus and Callionymidae distinguished the ichthyofauna of the bank waters from that in the center of estuary and surf zones of sandy beaches have something in euryhaline and diadromous fishes.
Some of fish species occurring in the bank waters of the Shimanto estuary are also collected in the surf zones of sandy beaches. Among those species, the principal habitats is considered to be either of the two above-mentioned biotopes. For the Lateolabrax japonicus, for instance, the estuary is a main habitat, but not for the L.latus. Hence it is found that the community of fish larvae and juveniles mainl
… More
y occupying the bank waters of the estuary is an exceptional species which has successfully adapted to estuary environment characterized by a relatively low salinity condition.
The three sparines move from non-eelgrass habitats to eelgrass beds in the bank waters of the estuary at the early juvenile stage. Thus those fishes are categorized as migrant species within the non-eelgrass area which they use as a hbitat only for a brief time. Consequently, it seems that the role of the non-eelgrass habitats in the bank waters as a nursery for these species is similar to that of the surf zones on sandy beaches that are occupied by migrant species. Subsequently, they reside in eelgrass beds at least until the late juvenile or young stage. During this timem, they transform to demersal habit, and feed on benthic animals in eelgrass beds. Thus the eelgrass beds seem to play an important role in their settlement.
As a consequence, the bank waters of the estuary consisting of non-eelgrass areas and eelgrass beds is found to be an important nursery where the exceptional species adapted to low salinity environment can spend a great part of their early life history. Less
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