M.S. Marine Biology
Second Degree Name
M.S. Coastal Zone Management
Daniela Silvia Pace
The subpopulation of sperm whales (Physeter macrocephalus) in the Mediterranean Sea is presently list as “Endangered”. This study is an attempt to provide detailed data on sperm whale Bachelor Groups surrounding Ischia, Italy in the Tyrrhenian Sea (Mediterranean Sea). 24 hours, 38 minutes, and 38 seconds of sperm whale Bachelor Group acoustic data was analyzed in order to describe acoustic repertoire, classify behavioral associations to acoustic types, and identify habitat-use. The data showed that the acoustic repertoire of sperm whale Bachelor Groups is dominated by Usual Clicks. Additionally, a click type that maintains an inter-click interval (ICI) in between Usual Clicks and Creaks was identified during acoustic analysis and named “Transition Clicks”.
Acoustic events were categorized into Single Code and Combination Code events; representing situations where one acoustic code was heard versus situations where two or more different acoustic codes were heard simultaneously. Analysis revealed that Single Code events represented 71.25% of the sperm whale Bachelor Group acoustic repertoire. The Usual Click/ Transition Click combination represented 73.74% of Combination Code events. A significant difference was shown between time spent in Single Code versus time spent in Combination Code for Usual Clicks and for Squeals. Acoustic repertoire data revealed the possibility for a strong collaborative acoustic structure and a speculated strategy for evolutionary success among sperm whale Bachelor Groups in Ischia, Italy.
Additionally, the study showed that sperm whale Bachelor Groups spend 77.87% of the analyzed time engaged in orientation/searching/foraging behavior and 1.09% engaged in socializing behaviors. Event maps revealed a ‘hotspot’ of sperm whale Bachelor Group activity in the waters to the northwest of Ischia, Italy, within the submarine Canyon of Cuma, and outside of the boundaries for the Regno di Nettuno Marine Protected Area (MPA).
It is recommended that the results of this study be utilized in extending the Regno di Nettuno MPA to include the ‘hotspot’, and possible critical area, for sperm whale Bachelor Groups. The results of this study and published literature of the sperm whales in this area could be utilized to create population-specific management strategies for more effective measures in ending population decrease and preserving the species. Further research should be carried out to analyze in detail the role of Transition Clicks in sperm whale acoustics and the possibility of a collaborative acoustic structure that has yet to be displayed in any other sperm whale population worldwide.
Cristina M. Ledon. 2016. Acoustic Repertoire of Sperm Whale (Physeter macrocephalus) Bachelor Groups in the Waters Surrounding Ischia, Italy (Tyrrhenian Sea). Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (425)