Northwest Atlantic fin whale vocalizations: geographic variations and implications for stock assessments
Acoustics has been increasingly used for research on marine mammals as it provides a window into their underwater behavior, allows studying their distribution, movement patterns and relationships and may eventually become a standard stock assessment tool. Fin whales produce low-frequency sounds that have the potential to propagate over long-distances and are the most commonly recorded species in the North Atlantic. Thus, the application of acoustic methodologies to this species may offer rewarding results. This thesis first investigated the use of passive acoustics in defining fin whale stocks. The structure of songs recorded at two northwest Atlantic feeding aggregations was compared to evaluate whether songs provide a mean to characterize these aggregations. Fin whales residing on geographically isolated feeding grounds may face different conservation issues and there are obvious management benefits to identifying and tracking acoustically different fin whales. Songs appear to characterize fin whale aggregations reliably, and the results are consistent with the stock structure derived from other assessment methods. A second part of the study consisted in describing a lesser known part of fin whales’ vocal repertoire. Although fin whale songs and their 20-Hz pulses are well described, social sounds produced in summer months have not received the same amount of attention. Eight call types reflecting the natural sound diversity were characterized. Comparisons of the same calls from different regions xi provided preliminary evidence of geographic variations. In addition, sounds that may be most suitable for summer acoustic census were identified. In summary, this thesis demonstrates the potential of using acoustics to assess fin whale biological parameters that are relevant to the conservation and management of that species.
Delarue, Julien. 2008. Northwest Atlantic fin whale vocalizations: geographic variations and implications for stock assessments. Master of Philosophy in Human Ecology, B.S. Hawaï Pacific university, Hawaï, USA.
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