Whale-watching vessels contribute to elevated ambient sound levels in marine habitats. The reduction in maritime tourism activities during the Covid-19 pandemic provided an unprecedented opportunity to study the acoustic response of marine mammals to noise associated with whale-watching activities. In this study, we used acoustic recordings, visual observations, and Automatic Identification System data to determine the changes in humpback whale Megaptera novaeangliae calling behavior associated with whale-watching vessels on a foraging ground in Skjálfandi Bay, Iceland. We compared pre-pandemic summer months (2018) with pandemic (2020) conditions to quantify reductions in vessel activity and determine changes in calling behavior. Broadband ambient sound pressure levels were low in both years (median ~90 dBRMS (25−1300 Hz) re 1 μPa). During the Covid-19 pandemic (2020), the number of whale-watching trips was reduced by 68.6%. The number of humpback whale call detections increased nearly 2-fold. Ambient sound pressure levels stayed the same. We found that humpback whales reduce their calling effort in the presence of vessel sound independent of the overall ambient sound. As whale-watching vessel traffic rebounds and continues to grow, demonstrating behavioral responses should inform management plans such as vessel codes of conduct and marine spatial planning.
|Tidsskrift||Marine Ecology Progress Series|
|Status||Udgivet - 24. nov. 2022|
Bibliografisk noteFunding Information:
Acknowledgements. We acknowledge Aðalgeir Bjarnason and Charla Basran for hydrophone deployment, retrieval, and support. Thank you to Paul Wensveen for providing the deck unit and to Aran Mooney for providing the DSG recorder used to collect the 2018 acoustic data. We extend our gratitude to the whale-watching companies, whale-watching guides, the research center staff, and the people of Húsavík for the good collaboration and their support. Special thanks to Benjamin Hildebrand for the intellectual support and critical thinking. AIS data were provided by the Icelandic Coast Guard. Earthquake data were provided by the Icelandic Meteorological Office. Partial funding for this research was provided by an NSF-Fulbright Arctic Research Scholar fellowship awarded to A.S.
© Inter-Research 2022.