Blue whale calling in the Rottnest trench-2000, Western ... - ANP

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Figure 7: Spectrogram and waveform of the type I and III components. Waveform high pass filtered using a 5 Hz, 5th order Butterworth filter. Figure 8: Spectrogram and waveform of type III component (over 26-48 s). Several other lower level component types from different singers can also be seen (for example a type II component overlapping the end of the type III component). 12
Figure 9: Bandpass filtered waveforms of type III component shown on Figure 8. This call type is similar, although not exactly the same, to spectrograms displayed by Cummings and Thompson (1971) from blue whale calls recorded off Chile in 1970. The three call components were remarkably stereotyped in individual structure and in the timing between adjacent components. The distribution of the spectral peak frequency of 404 components (recorded across a 7 day period from the bluey logger) determined from FFT averages at a resolution of 0.0763 Hz over the full duration of each component, is shown on Figure 10. The type III component spectral peak frequency was centred almost exclusively near 19 Hz, the spectral peak frequency of the type I component varied over approximately a 1 Hz band centred near 21.2 Hz (the lower level leading tone does not show in this analysis), and the type II component spectral peak frequency varied, which reflected its frequency sweep nature. The frequency spectra of three high SNR components indicating the sharp tonal nature of components is shown on Figure 11. An example of the amplitude modulation within components can be seen on Figure 12 where a type I component displays strong sidebands which shift frequency with time. 13
Page 1 and 2: Centre for Marine Science and Techn
Page 3 and 4: Contents Abstract..................
Page 5 and 6: Along the Western Australian coast
Page 7 and 8: Figure 2: Location of the Rottnest
Page 9 and 10: Figure 4: Examples of temperate (th
Page 11: The first call component, referred
Page 15 and 16: Figure 12: Spectrogram of two blue
Page 17 and 18: For the final censusing technique a
Page 19 and 20: the medium sand thickness was linea
Page 21 and 22: interference patterns produced by t
Page 23 and 24: coast. Calling depths of 22-34 m, a
Page 25 and 26: of the same frequency, different ph
Page 27 and 28: Figure 23: Distribution of 'possibl
Page 29 and 30: Figure 26: Predicted ranges for the
Page 31 and 32: 31 and Figure 32. These also displa
Page 33 and 34: signals were received with a wide r
Page 35 and 36: each time point tested. All calcula
Page 37 and 38: Figure 37: Arrangement of kernel (a
Page 39 and 40: 16:00) using combinations of mean c
Page 41 and 42: Figure 40: (top) Number of callers
Page 43 and 44: 2. and the type II component call s
Page 45 and 46: Figure 43: Number of callers averag
Page 47 and 48: Figure 47: Time averaged spectra (1
Page 49: Figure 51: Time averaged spectra (1
Page 52 and 53: each block then gave the total numb
Page 54 and 55: 5) References Bannister, J.L. (1993

Blue whale calling in the Rottnest trench-2000, Western ... - ANP

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