2023 Fiscal Year Final Research Report
Detection of maternal effects using field-collected Pacific cod larvae and juveniles and its application to resource management
| 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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| Keywords | 母親効果 / マダラ / 孵化日 / 耳石 / 生残 |
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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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| Free Research Field |
魚類生産生態学
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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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