Impacts of the tsunami associated with the 2011Great Earthquake in East Japan on the populations of salmon and ayu in Sanriku coast of northern japan

2015 Fiscal Year Final Research Report

• Project/Area Number: 24380105
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: General fisheries
• Research Institution: The University of Tokyo
• Principal Investigator: Otake Tsuguo 東京大学, 農学生命科学研究科, 教授 (20160525)
• Co-Investigator(Kenkyū-buntansha): SHIRAI Kotaro 東京大学, 大気海洋研究所, 助教 (70463908)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 東日本大震災 / サケ / アユ / 耳石 / 微量元素組成 / 安定同位体比 / 資源

Outline of Final Research Achievements

Otolith chemical composition of juvenile chum salmon was found to well discriminate the juveniles from different hatcheries within the same area. The analysis through the life history for adult from Hokkaido coast and immature fish from the Bering Sea revealed that otolith Sr:Ba ratios periodically fluctuated. These suggest that otolith chemical analysis can provide important information to reveal the effects of the 2011 Tsunami of the Great East Japan Earthquake on the migration history and homing behavior.
The upstream migrants of ayu immediately after the tsunami were found to be solely composed of fish hatched during October-November, whereas those before the tsunami were mostly composed of fish hatched in September. The shift of hatch dates was found to result of the selective mortality of early hatched fish occurred during the tsunami. The hatch date composition of upstream migrants returned to the state before the tsunami in 2013-2014, but the sizes were observed to decrease.

Free Research Field

魚類生態学