1997 Fiscal Year Final Research Report Summary
How do eggs and larvae come to nursery beyond front?
| Project/Area Number |
08660223
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
MATSUSHITA Katsumi The University of Tokyo. Graduate School of Agricultural & Life Science. Department of Aquatic Bioscience.Assistant Professor, 大学院・農学生命科学研究科, 助手 (00012039)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Japanese anchovy / Recruitment / Drift card |
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| Research Abstract |
Most pelagic fish spawn their eggs at offshore area but the nursery is usually coastal area. We sometimes detected the patches of eggs and larvae at the frontal area as like they were induced to stay at the front. How do the eggs and larvae enter and/or entrainment nursery beyond the front?
I suspected the recruitment success of white bait fishery may be influenced by the entrainment from offshore spawning area beyond the front. The catch of white bait fishery is very fluctuate though the spawning potential is constant. I evaluated the entrainment by using 4 methods.
(1)grid survey the distribution and abundance of eggs at frontal area by HCPS.
(2)grid survey the distribution and abundance of eggs at offshore area by CPS.
(3)spawning daily population index of white bait fishery by otolith analysis.
(4)drift card return ratio to the coastal area.
The HCPS grid survey lines were araanged to cross the front, then I could detect the front and anchovy eggs patches accumulated along frontal area. At the same time. the drift cards were thrown at each continuous station. The survey of offshore distribution of eggs were also carried out by CPS.Furthermore, I collected anchovy larvae of white bait fishery and the data of catch per haul each 5 days between 10-30 days period after eggs distribution survey. The collected larvae were analyzed the otolith and estimated the birth date. Then, I could estimate the spawning daily population index of the day of eggs distribution survey. The spawning daily population index is not directly correlated to the abundance of eggs at frontal area. The drift card return ratio to the coastal area is more important to predict the spawning daily population index. Then, I supposed the recruitment success of white bait fishery is influenced by the physical entrainment.
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Research Products
(2 results)
