Steady inter and intra-annual decrease in the vocalization frequency of Antarctic blue whales
MetadataShow full item record
Copyright © 2012 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.
Time averaged narrow-band noise near 27 Hz produced by vocalizations of many distant Antarctic blue whales intensifies seasonally from early February to late October in the ocean off Australia’s South West. Spectral characteristics of long term patterns in this noise band were analyzed using ambient noise data collected at the Comprehensive Nuclear-Test-Ban Treaty hydroacoustic station off Cape Leeuwin, Western Australia over 2002–2010. Within 7 day averaged noise spectra derived from 4096-point FFT (~0.06 Hz frequency resolution), the −3-dB width of the spectral peak from the upper tone of Antarctic blue whale vocalization was about 0.5 Hz. The spectral frequency peak of this tonal call was regularly but not gradually decreasing over the 9 years of observation from ~27.7 Hz in 2002 to ~26.6 Hz in 2010. The average frequency peak steadily decreased at a greater rate within a season at 0.4–0.5 Hz/season but then in the next year recovered to approximately the mean value of the previous season. A regression analysis showed that the interannual decrease rate of the peak frequency of the upper tonal call was 0.135 ± 0.003 Hz/year over 2002–2010 (R 2 ≈ 0.99). Possible causes of such a decline in the whale vocalization frequency are considered.
Showing items related by title, author, creator and subject.
Salgado Kent, Chandra; Gavrilov, Alexander; Recalde-Salas, A.; Burton, C.; McCauley, R.; Marley, S. (2012)Baleen whales were monitored in Geographe Bay, Western Australia between 2008 and 2011 using passive acoustics. We aimed to monitor migratory timing through Geographe Bay, characterise whale vocalizations, and estimate ...
Acoustic detection and long-term monitoring of pygmy blue whales over the continental slope in southwest AustraliaGavrilov, Alexander; McCauley, Robert (2013)A 9-yr dataset of continuous sea noise recording made at the Cape Leeuwin station of the Comprehensive Nuclear-Test-Ban Treaty hydroacoustic network in 2002–2010 was processed to detect calls from pygmy blue whales and ...
Gavrilov, Alexander; McCauley, Robert; Salgado Kent, Chandra; Tripovich, J.; Burton, C. (2011)Vocal characteristics of pygmy blue whales of the eastern Indian Ocean population were analyzed using data from a hydroacoustic station deployed off Cape Leeuwin in Western Australia as part of the Comprehensive ...