Life history of chum salmon Onchorhynchus keta during the period migrating in the North Pacific inferred from scale and otolih elemental and stable isotopic compositions

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H04543
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Aquatic bioproduction science
• Research Institution: The University of Tokyo
• Principal Investigator: Otake Tsuguo 東京大学, 大気海洋研究所, 特任研究員 (20160525)
• Co-Investigator(Kenkyū-buntansha): 白井 厚太朗 東京大学, 大気海洋研究所, 助教 (70463908)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: サケ / 鱗 / 耳石 / 安定同位体比 / 微量元素

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.

Free Research Field

魚類生態学