Acoustic responses of white-beaked dolphins (Lagenorhynchus albirostris) to changes in maritime traffic A case study in Skjálfandi bay, Iceland

The worldwide spread of Covid-19 and the ensuing period of reduced human activity – the “anthropause” – created an opportunity for researchers to study the effects of quieter oceans on wildlife. Skjá lfandi Bay in the northeast of Iceland provides habitat for a wide range of cetaceans. In this bay, whale-watching operations began in 1995 and continue to attract thousands of tourists each year. This study investigates the changes in maritime traffic associated with the Covid-19 pandemic and the impact on the communication of white-beaked dolphins (Lagenorhynchus albirostris) using passive acoustic monitoring, visual observations, and Automatic Identification System (AIS) data. White-beaked dolphins tended to whistle more during periods of low traffic with two times more whistles heard on average in the evening and at night, or when local maritime traffic was disrupted in 2020, with significant differences compared to the same period in 2022 (p=0.04). A better understanding of the anthropogenic impacts on marine fauna could lead to more effective regulations in Skjá lfandi Bay, and could also serve as a basis for further studies elsewhere in Iceland or in other countries.