1987 Fiscal Year Final Research Report Summary
Ecological studies on the formation mechanisms of Shirasu (anchovy and sardine larvae) fishery ground.
| Project/Area Number |
61480066
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Ocean Research Institute, University of Tokyo |
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Principal Investigator |
KAWAGUCHI Kouichi Assoc. Prof. Ocean Res. Inst., Univ. of Tokyo, 海洋研究所, 助教授 (40013586)
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| Co-Investigator(Kenkyū-buntansha) |
YAMASHITA Yoh Res. Assoc., Ocean Res.Inst., Unive. of Tokyo, 海洋研究所, 助手 (40166682)
ISHIMARU Takashi Res.Assoc., Ocean Res. Inst., Univ. of Tokyo, 海洋研究所, 助手 (90114371)
UOTANI Itsurou Assoc. Prof., Dept.Oceanogr., Tokai University, 海洋学部, 助教授 (20056295)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Anchovy / Sardine / Daily ring / Otolith / Point of No Return / Fish larvae / Survial rate / 感覚器 |
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| Research Abstract |
The main purpose of the project is to accumulate the knowledges on biological nature of Shirasu(anchovy and sardine larvae) itself to explain formation mechanisms of the fishery ground. The results obtained are summarized as follows.
1. Biological characteristics of Japanese anchovy (Engraulis japonica)
(1) The development of sensory organs (eye, olfactory organ, lateral line sytem etc.) was studied in relation to the behavioral changes.
(2) Point of No Return (PNR) of first feeding larvae was estimated 1-1.5 days.
(3) The minimum density of prey for survival was estimated 5000 inds. rotifer/l level.
(4) Two species of dinoflagellate Gyrodinium instriatum and Gymnodinium splendens which are common in Japanese coastal waters are effective to prolong PNR, but not perfect prey itself for suvival of larvae.
(5) Establishment of histological technique to determine the starving condition of larvae.
(6) Gut content analysis of field collected larvae in relation to morphological change in different developmental stages.
2. Biological characteristics of Japanese sardine (Sardinops melanosticta)
(1) It was proved that one ring is formed daily on otolith of larvae, and the first ring is formed 2-3 days after hatching coinciding with the first feeding.
(2) Gut content analysis of field collected larvae in relation to morphological change in different developmental stages.
3. Adult anchovy had been successfully reared in closed circulation system in laboratory under the controlled condition and spawned every day for 6 months.
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