| Project/Area Number |
14206023
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 |
WATANABE Yoshiro The University of Tokyo, Ocean Research Institute, professor, 海洋研究所, 教授 (90280958)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAKIHARA Kunio The University of Tokyo, Ocean Research Institute, professor, 海洋研究所, 教授 (90196618)
MATSUDA Hiroyuki Yokohama National University, Graduate School of Environment and Information Sciences, professor, 環境情報研究院, 教授 (70190478)
SARUWATARI Toshiro The University of Tokyo, Ocean Research Institute, Research Associate, 海洋研究所, 助手 (00215899)
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| Project Period (FY) |
2002 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥52,780,000 (Direct Cost: ¥40,600,000、Indirect Cost: ¥12,180,000)
Fiscal Year 2005: ¥8,840,000 (Direct Cost: ¥6,800,000、Indirect Cost: ¥2,040,000)
Fiscal Year 2004: ¥9,880,000 (Direct Cost: ¥7,600,000、Indirect Cost: ¥2,280,000)
Fiscal Year 2003: ¥11,440,000 (Direct Cost: ¥8,800,000、Indirect Cost: ¥2,640,000)
Fiscal Year 2002: ¥22,620,000 (Direct Cost: ¥17,400,000、Indirect Cost: ¥5,220,000)
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| Keywords | fish resorces / natural fluctuation / clupeids / Pacific saury / life history strategy / management fish stock / 大変動 / ニシン / キビナゴ / 初期減耗 / 仔稚魚 / 加入量変動 / 耳石日輪 / 再生産戦略 / マサバ / 変動様式 / 成長速度 / 生残率 |
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| Research Abstract |
Latitudinal difference in population fluctuations in fish stocks in the southern subtropical and northern subarctic waters is distinct among 3 species of clupeid fishes, between 2 subpopulations of chub mackerel Scomber japonicus, and among 3 cohorts of Pacific saury Cololabis saira ; largely variable in the northern waters, relatively stable in the southern counterparts. This latitudinal difference is environmentally based in a species of chub mackerel of Pacific saury. In clupeid species, on the other hand, they are different in species and in reproductive strategies. Latitudinal difference in clupeid fishes are considered to be genetically based as well as environmentally induced. Through the course of evolution from the ancestor of clupeid fishes inhabiting the southern waters, herring have developed reproductive strategy that is adaptive to the variable environmental conditions in the subarctic waters.
Iteroparity and indeterminate growth are reproductive strategies that are adaptive to variable environmental conditions in the northern waters. This bet-hedging strategies are understood to reduce the magnitude of recruitment variability by spawning multiple years and by allocating energy intake to reproduction as well as growth after the age-at-maturity. Nevertheless, recruitment variability is large in the species. If the species were semelparous and/or determinate in growth, it should have become extinct or it should not be capable of expanding to the northern waters. Recruitment variability, in other words, recruitment failure and occurrence of dominant year classes are inevitable in the northern waters. Adaptive management of the northern fishery stocks of these characteristics need to be adaptive to large variability in the recruitment. The yield-per-recruitment policy may be a choice for stock management of the variable northern species.
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