MicroTech Innovation (Norway)

Understanding marine mammal behavior and distribution is important for marine ecosystem management and assessing anthropogenic impacts. However, persistent and concurrent observations of large marine mammals such as sperm whales, their prey field, and physical oceanographic processes are lacking. In this study we demonstrate the ability of a cabled ocean observatory to perform such observations. Using echosounder and hydrophone data collected by Node 1 of the Lofoten-Vesteralen Ocean Observatory (LoVe Ocean, N 68 °54’, E 14 °23’, 257 m depth) we demonstrate the observatory’s capability for concurrently detecting and quantifying the behavior of shallow foraging sperm whales (Physeter macrocephalus) and mesopelagic prey layer. Sperm whale clicks and creaks were detected by the observatory hydrophone while the echosounder provide water column backscatter. The avoidance reaction by the mesopelagic layer is quantified and shown to be predominantly vertical, in the instance where one sperm whale descends from above the observatory echosounder. This study demonstrates the value of LoVe Ocean and similar infrastructure as in situ laboratories for marine mammal behavior and effect studies, in order to further our understanding of ecosystem variability.