2019 Fiscal Year Final Research Report
Understanding the factor of chum salmon decline using carbon and nitrogen stable isotope analysis
| Project/Area Number |
17K15312
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Aquatic bioproduction science
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| Research Institution | Hokkaido Research Organization |
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Principal Investigator |
KOSHINO Yosuke 地方独立行政法人北海道立総合研究機構, 水産研究本部 さけます・内水面水産試験場, 主査 (20747092)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | サケ / 安定同位体 / 成長率 / 鱗 |
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| Outline of Final Research Achievements |
In this study, we studied differences in feeding habitat and the trophic status of salmon in early marine life and during foraging migration between Abashiri and Shibetsu area, northeastern Hokkaido. Juveniles collected in the Abashiri were larger in size and grew faster than those collected in the Shibetsu. The low carbon stable isotope ratio in muscle suggested that cold-water copepods, a preferred food source for salmon, were mainly used. The carbon and nitrogen stable isotope ratios in the outer age circuli of adults returned in 2018,were notably low. These results indicate that stable isotope analysis may be useful in assessing the diet and the trophic status of salmon in marine life stage.
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| Free Research Field |
魚類生態学
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| Academic Significance and Societal Importance of the Research Achievements |
現在、サケの来遊数が過去にないレベルで減少しており、その減少要因の解明が強く求められている。本研究により、餌生物の種類が成長に影響する可能性があることが分かった。このことは、サケの増殖事業を行う上で、稚魚の放流タイミングの再検討に重要な結果となる。また、これまではサケは稚魚期に大きく減耗すると考えられていたが、外洋においても回遊経路あるいは餌生物が違うことなどで成長が停滞し、大きな減耗に繋がる可能性があることが、本研究で初めて示された。
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