Vocalizations of blue whales in the Antarctic: Implications for the use of passive acoustics for population studies on baleen whales

Stereotypical calls of baleen whales can be a diagnostic field characteristic for determining species and stocks. Repeated series of these calls may be used for long‐term population studies using passive acoustics. Vocalizations were recorded from 15 groups of blue whales (consisting of 42 individuals) during the 2001–02 and 2002–03 International Whaling Commission‐Southern Ocean Whale and Ecosystem Research (IWC‐SOWER) surveys in Antarctic waters north and east of the Ross Sea. Long‐duration vocalizations attributed to Antarctic blue whales included 28‐Hz ‘‘tones,’’ 28 Hz ‘‘downsweeps,’’ and the more complex ‘‘3‐unit’’ calls (considered to be song units). The 28‐Hz component was stable for all three calls, regardless of signal strength. The 3‐unit calls varied in their 2nd and 3rd units and were heard in only 10 out of the 15 groups. There was no evidence of repeated patterns (song phrases) of 3‐unit calls. The results of this study suggest that the 28‐Hz peak frequency may be used as a diagnostic featur...