This is a parent record for data collected from AAS project 4102. Project 4102 also follows on from ASAC project 2683, "Passive acoustic monitoring of antarctic marine mammals" (see the related metadata record at the provided URL). Public Summary: Half a century ago the Antarctic blue whale was perilously close to extinction. Over 350,000 were killed before the remaining few were fully protected. A decade ago this elusive and poorly understood species was estimated to be less than 5% of its pre-whaling abundance. This multi-national, circumpolar project will develop and apply powerful new techniques to survey these rare whales and gain an insight into their recovery and ecology. The project is the flagship of the Southern Ocean Research Partnership - an International Whaling Commission endorsed collaborative program.

This dataset contains acoustic recordings from Directional Frequency Analysis and Recording (DIFAR) sonobuoys that were deployed during the 2013 Antarctic blue whale voyage. During the 47 day voyage 360 sonobuoys were deployed yielding 733 hours of acoustic recordings. On average, slightly more than eight sonobuoys were used per survey day. Ninety three sonobuoys were deployed in transit to or from the edge of the sea-ice while the remainder were deployed to monitor and target Antarctic blue whales. The telemetered audio from sonobuoys was monitored aurally and visually (via spectrogram) in real-time by one or more on-duty acousticians. A total team of five dedicated acousticians monitored round-the-clock for blue whales and in all weather conditions. Upon detection of blue whale vocalisations the vessel was directed towards the locations of these sounds. After deployment, sonobuoys sent acoustic and directional data to the ship via a VHF radio transmitter. Radio signals from the sonobuoy were received using an omnidirectional VHF antenna (PCTel Inc. MFB1443; 3 dB gain tuned to 144 MHz centre frequency) and pre-amplifier (Minicircuits Inc. ZX60-33LN-S+) mounted on the mast of the ship at a height of 21 m. The preamplifier was connected to a power splitter via LMR400 cable and signals were received with two WiNRaDiO G39WSBe sonobuoy receivers. The radio signal from sonobuoys was adequate for monitoring and localization out to a typical range of 12-15 nmi. Received signals were digitised via a sound board (RME Fireface; RME Inc.), and signals were recorded on a personal computer using the software program PAMGuard (Gillespie et al. 2008). Three models of sonobuoys were used during the voyage: 79 were AN/SSQ-53D (Ultra Electronics, Canada), 81 were AN/SSQ-53F (Ultra Electronics: SonobuoyTechSystems, USA) and 200 were AN/SSQ-955-HIDAR (deployed in DIFAR compatibility mode; Ultra Electronics Sonar Systems, UK). In addition to recording of Antarctic blue whale song, New Zealand type blue whale song, and blue whale "D-call" vocalisations, these recordings also contain vocalisations from fin whales, humpback whales, sei whales, killer whales, sperm whales, as well as low frequency sounds from Antarctic sea ice.