FISHERY BULLETIN: VOL. 84, NO. 2 



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TIME IN SECONDS 



Figure 6— Spectrograms of typical 68/34-Hz moans from finback whales recorded off Isla Angel de la Guarda. The first component of 

 the moans began at 65 Hz and increased to 68 Hz in the first sec It was accompanied by weaker modulation products at about 23-Hz 

 intervals, mostly above the main frequency. The 34-Hz component followed and sometimes overlapped the first component (lower spec- 

 trogram). The effective analyzing filter bandwidth was 3 Hz. 



of the sounds was 165 dB in the effective band- 

 widths. 



Of the 50 long moans from finbacks that were 

 analyzed, the mean frequency of the main, or first, 

 component was 68.2 Hz; the mean frequency at onset 

 being 66.1 Hz. The mean duration was 1.5 s. Thirty 

 moans exhibited additional lower frequency compo- 

 nents with a mean frequency of 33.5 Hz and a mean 

 duration of 1.3 s. The overall mean duration of these 

 two-part moans was 3.1 s. The 365 moans of this type 

 encountered in Contacts 7 and 8 occurred on the 

 average of 1.6 and 2.2 times/min, respectively. 



In the case of unidentified balaenopterid whales, 

 the mean frequency of the strongest component of 

 the 68 miscellaneous moans analyzed was 58.5 Hz 

 (range from 15 to 95 Hz), and the mean duration was 

 0.8 s. Of these sounds <10% had any frequency shift 

 >10 Hz. Thirty-seven of the analyzed moans were the 

 same as the long two-part moans recorded in the 

 presence of finbacks. Their mean frequencies were 



68.1 and 34 Hz, the mean component duration was 

 1.9 and 2.6 s, respectively, and the mean total dura- 

 tion was 3.4 s. The mean starting frequency of the 

 68-Hz component was 63.9 Hz. These two-part 

 moans occurred at a rate of 1.5 to 3.2/min. Overall 

 source levels ranged from 159 to 183 dB in the ef- 

 fective frequency bandwidth. 



The blows of finback whales were as high as about 

 7 m above the water's surface, and often they were 

 clearly audible in air at distances out to 200 m. The 

 last blow in a series was followed by an inhalation 

 that sometimes involved a low-frequency whistlelike 

 sound just before a long dive (Fig. 7). The physical 

 characteristics of blow sounds varied slightly from 

 one whale to another, providing a certain degree of 

 uniqueness for an individual whale (Fig. 7). Wheez- 

 ing, shriek, and hornlike sounds produced by hump- 

 back whales in association with their blows have been 

 described by Watkins (1967) and Thompson et al. 

 (1977). 



366 



