| Budget Amount *help |
¥11,180,000 (Direct Cost: ¥8,600,000、Indirect Cost: ¥2,580,000)
Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2015: ¥8,320,000 (Direct Cost: ¥6,400,000、Indirect Cost: ¥1,920,000)
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| Outline of Final Research Achievements |
Stable isotope analysis (SIA;δ15N、δ13C) of scales from chum salmon (Oncorhynchus keta) ascending the Tsugaruishi River (Iwate Prefecture) in the 1980s and 2010s revealed that food item of 2010s fish during their migration in the North Pacific did not differ from that of 1980s fish. Younger aged (two-year-old) fish comprised of small sized one has higher relative growth rate during last growth period (RGR) with higher scale δ15N than fish of higher ages, suggesting that they inhabited an feeding environment that yielded higher SI in early migration period. It also indicates that they might have a migration route different from the other aged fish havinglowerRGR and lower SI. Otolith elemental analysis revealed that Ba/Ca, Li/Ca and Sr/Ca periodically fluctuated in the otolith portion corresponding to the migration period in the North Pacific. Those peak positions and levels were different among the individual origins, suggesting that migration route varied among origins.
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