| Project/Area Number |
21K05723
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 40030:Aquatic bioproduction science-related
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
中屋 光裕 北海道大学, 水産科学研究院, 准教授 (80604313)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2023: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2022: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2021: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 母親効果 / マダラ / 孵化日 / 耳石 / 生残 / 成長仮説 / 被食仮説 |
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| Outline of Research at the Start |
我が国冷水域に広く生息するマダラは産業重要種のひとつであり，漁獲可能量（TAC）による資源管理が推進されている魚種である。しかしマダラは，親魚が多ければ稚魚も多いといった明瞭な「親子関係」はないために，加入量予測は実現していない。本研究は資源が変動しやすい仔稚魚期の耳石から，母親魚の体長や年齢などの検出を試みて，質の高い卵を産む母親魚を選択的に獲り残す資源管理が有効かどうか検証する研究である。
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| Outline of Final Research Achievements |
We attempted to elucidate the causes of stock fluctuations by detecting the "maternal effect" in Pacific cod larvae and juveniles and simultaneously examining various hypotheses related to early life survival. As a result of rearing experiments using artificial fertilization, we have been able to estimate the body length of field-collected individuals at hatching based on otolith diameter at hatching. The survival rate of larvae and juveniles collected in Mutsu Bay was higher in lower water temperature years from mid-February to early March, and was highest at 7.6°C from late March to late May. Comparison of stomach content composition of juveniles collected from late May to June between years indicated that encounters with larger-sized prey were important for improving the nutritional status of juveniles. In 2022, pelagic larvae hatched early in the spawning season were rarely survived to the juvenile stage, suggesting that there may have been many predators.
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| Academic Significance and Societal Importance of the Research Achievements |
陸奥湾のマダラの初期生残は、各発育段階で様々な要因が影響していることが明らかとなった。しかし、雌親の年齢や体サイズ・栄養状態等の遺伝的ではない後天的な形質が、仔の生残率に影響を及ぼすと考える「母親効果」は限定的だった。そのため、マダラについては生残しやすい卵仔稚魚を産む雌親魚を重点的に獲り残す資源管理はあまり期待できず、未成魚期から成魚期にかけての漁獲管理か、低資源状態での種苗放流が現実的と考えられた。今後は、近年本邦周辺海域で顕著な海洋の高水温化がマダラの初期生残におよぼす影響と、人為的漁獲強度の年変化を定量的に評価し、資源量変動予測の実現を目指す必要がある。
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