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2019 Fiscal Year Final Research Report

Environmental monitoring of mesopelagic ecosystem using marine top predators as an indicator

Research Project

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Project/Area Number 17K12813
Research Category

Grant-in-Aid for Young Scientists (B)

Allocation TypeMulti-year Fund
Research Field Environmental dynamic analysis
Research InstitutionThe University of Tokyo

Principal Investigator

Aoki Kagari  東京大学, 大気海洋研究所, 助教 (60526888)

Project Period (FY) 2017-04-01 – 2020-03-31
Keywords海生哺乳類 / 高次捕食者 / 鯨類 / 海洋生態系 / 中深層生態系 / バイオロギング / 肥満度 / 採餌行動
Outline of Final Research Achievements

Behavioral responses and body conditions of marine top predators can be good indicators of environmental changes in marine ecosystem. However, it is challenging to investigate the body conditions of free-ranging whales in the ocean without killing them. In addition, deep-diving toothed whales, that reciprocate between the sea surface and the mesopelagic zone, can be an efficient platform to monitor the surrounding environment. Here we focused on the three topics to establish a method to measure the environmental responses of cetaceans: 1) non-invasive monitoring methods to estimate seasonal changes in body condition of humpback whales at feeding grounds using aerial photogrammetry and tag-derived tissue density, 2) long-term monitoring behaviors of sperm whales and 3) monitoring feeding behavior of toothed whales using animal-born recorders. Our final goal is to establish to monitoring methods of ocean health via the environmental responses of marine top predator as indicators.

Free Research Field

鯨類の行動生態

Academic Significance and Societal Importance of the Research Achievements

広大な海洋で、動物が変化する環境にどのように応答するのか把握することは難しい。動物に記録計を装着しその行動を記録するバイオロギングは、動物の環境応答を直接計測できる。
また、一部の鯨類ではかつての商業捕鯨により個体数が激減し、さらに近年では海中騒音や漁業による混獲など、人間活動の影響を大きく受ける。海洋生態系のピラミッドを上位から支える役割を持つ高次捕食者が危機的な状況に追い込まれると、その影響が生態系下位の動植物の増減に影響を及ぼし、海洋生態系全体のバランスが崩れ壊滅的な影響を被る恐れがある。海洋の高次捕食者である鯨類の栄養状態や動態を知ることにより、海洋の健全性を評価できると考えられる。

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Published: 2021-02-19   Modified: 2023-01-30  

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