Study on the conservation of blue whales

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K24380
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 1101:Environmental analyses and evaluation, environmental conservation measure and related fields
• Research Institution: Kobe University (2020-2021); The University of Tokyo (2019)
• Principal Investigator: Iwata Takashi 神戸大学, 海事科学研究科, 助教 (10636913)
• Project Period (FY): 2019-08-30 – 2022-03-31
• Keywords: シロナガスクジラ / バイオロギング / 海洋環境

Outline of Final Research Achievements

To reveal ecology of large baleen whales including blue whales, we investigated behaviour of baleen whales using animal-borne data loggers. Behavioural data of 6 blue whales and 14 humpback whales in Iceland during 2012-2022 periods were obtained. 1534 dives from blue whales and 6521 dives from humpback whales were recorded. The average number of foraging events per dive was calculated yearly from the behavioural data. The relationship between the number of foraging events and the water temperature (0m, 20m, 50m depth) was investigated. The relationship between number of foraging events and the water temperature at a depth of 50 m was shown negative correlation. It was suggested that baleen whales in the survey area are affected by changes in water temperature at a depth of 50 m because they forage prey species distributed in a depth of 30-60 m.

Free Research Field

動物生態学

Academic Significance and Societal Importance of the Research Achievements

海生哺乳類や海鳥類などの海洋高次捕食者の行動は生態系変動の指標として用いる試みがされている。一方で、大型ヒゲクジラ類の行動は調査をすることが難しいことから、それらを生態系変動の指標として用いられた例は少ない。本研究では大型ヒゲクジラ類であるシロナガスクジラとザトウクジラの複数年に渡る行動記録から、ヒゲクジラ類の採餌イベント数が深度50m付近の水温に影響されていたことを示した。ヒゲクジラ類の採餌行動が、気候変動に伴う生態系変動の指標となる可能性を示すことができた。