Baleen whale occurrence in the Norwegian Sea

The Norwegian Sea is a dynamic ecosystem that is experiencing a multitude of impacts from anthropogenic activities. As sentinels of climate change, marine mammals can be useful for understanding the scale and scope of some of these impacts. Previous studies of cetaceans in the Norwegian Sea have had a limited scope, focusing, for example, on summertime visual surveys, or studies in coastal fjords. However, as many cetacean species occupy pelagic waters year-round, increasing our understanding of their occurrence more broadly in the Norwegian Sea is necessary. Passive acoustic recorders were deployed year-round in the offshore waters of the Norwegian Sea between 2023 and 2025. A High-frequency Acoustic Recording Package was deployed 15 mi offshore from the outermost islands off central Norway from August 2023 to July 2024. Subsequently, a SonoVault was deployed at the continental shelf break approximately 200 mi further offshore from October 2024 until August 2025. The presence of several species of baleen whales, including blue, fin, humpback and minke whales, was analyzed to improve our understanding of their occurrence in this offshore ecosystem. This ongoing effort will shed light on the dynamics of baleen whale use of these waters and provide insights into their response to this changing ecosystem.