Marine mammals have been proposed to have a passively changing buoyancy that influences their swimming efforts depending on the depth, as a result of pulmonary alveolar compression/expansion as ambient pressure changes. Mysticetes have been described to have the same passive mechanism without considering their unique respiratory system, which may provide them with the ability to change their buoyancy actively to enhance vertical movements. Here, we present behavioral evidence supporting that adult mysticetes actively change buoyancy during shallow dives by analyzing diving data from multi-sensor tags placed on humpback whale mother–calf pairs. We show that adult female humpback whales display low effort to swim downward and upward regardless of the depth and can stay perfectly static (stationary) at different depths. In contrast, calves display depth-dependent swimming effort and only remain stationary with external help or at a specific depth. Our study adds to the body of evidence regarding the unique features of mysticetes' dives.

Keywords:
Active buoyancy control, Baleen whale, Cetacean, Mother–calf, Respiratory system, Swimming behavior

Author contributions

Conceptualization: M.N.R., O.A., C.H., J.S.R., A.S., A.A., I.C.; Data curation: M.N.R.; Formal analysis: M.N.R.; Funding acquisition: M.N.R., O.A., A.S., I.C.; Investigation: M.N.R., O.A., C.H., J.S.R., A.S., A.A., I.C.; Methodology: M.N.R., O.A., C.H., J.S.R., A.S., A.A., I.C.; Project administration: M.N.R., A.S., A.A., I.C.; Supervision: O.A., C.H., A.A., I.C.; Validation: M.N.R., O.A., C.H., J.S.R., A.S., A.A., I.C.; Visualization: M.N.R.; Writing – original draft: M.N.R., O.A.; Writing – review & editing: M.N.R., O.A., C.H., J.S.R., A.S., A.A., I.C.

Funding

This work was funded and supported by the IDEX Paris-Saclay [ANR-11-IDEX-0003-02], the Centre National de la Recherche Scientifique (CNRS), the Cétamada association, the Western Indian Ocean Marine Science Association (WIOMSA) [MARG-I-2021-CO-20], the Society for Marine Mammalogy [2021 SMM Research Grant], the Association for Tropical Biology and Conservation [ATBC seed grant], the CeSigma company, and donors who contributed to the KissKissBankBank crowdfunding for M.N.R.’s research.

Data and resource availability

All relevant data can be found within the article and its supplementary information.

ECR Spotlight

This article has an associated ECR Spotlight interview with Maevatiana Ratsimbazafindranahaka.

© 2025. Published by The Company of Biologists
2025
https://www.biologists.com/user-licence-1-1/
You do not currently have access to this content.