| Summary: | Progress Code: completed Statement: The acoustic data and detections were generally high quality. Some radio interference noise, presumably from the ship's AIS transmitter was regularly present on recordings in the form of short impulses. These noises were especially prevalent when sonobuoys were distant from the ship and sonobuoy radio signal strength was low. Purpose Sonobuoy data were used in real-time during ENRICH to adaptively determine survey lines and to ensure that the survey area contained Antarctic blue whales. The location of the oceanographic 'process station' during ENRICH was based on acoustic detections of Antarctic blue whales. The sonobuoy data also form a passive acoustic survey for marine mammals, particularly blue whales, fin whales, and sperm whales. This dataset contains acoustic recordings from Directional Frequency Analysis and Recording (DIFAR) sonobuoys that were deployed from 19 January – 5 March 2019 during the ENRICH (Euphausiids and Nutrient Recycling in Cetacean Hotspots) voyage. 295 sonobuoys were deployed yielding 828 hours of acoustic recordings. Passive acoustic research during ENRICH took the form of both broad-scale structured surveys and fine-scale adaptive surveys depending on the operational mode of the ship. Regardless of the mode of operation, listening stations were conducted by deploying SSQ955 sonobuoys (commonly called HIDAR sonobuoys) in Directional and Frequency Analysis and Recording (DIFAR) mode to monitor for and measure bearings to vocalising whales while the ship was underway (Miller et al. 2015). During transit, listening stations were conducted every 30 nmi in water depths greater than 200 m when Beaufort sea state was less than 7. During marine science stations, sonobuoys were deployed approximately 2-4 nmi prior to stopping in order to attempt to monitor them for the full six-eight hour duration of their operational life or the duration of the station. The sampling regime was chosen for compatibility with previous surveys, and to balance spatial ...
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