MODELLING SPERM WHALE HABITAT PREFERENCE: A NOVEL APPROACH COMBINING TRANSECT AND FOLLOW DATA

• Main Authors: Pirotta, Enrico, Matthiopoulos, Jason, MacKenzie, Monique Lea, Scott Hayward, Lindesay Alexandra Sarah, Rendell, Luke Edward
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2011
• Subjects: Sperm whale
• Online Access: https://research-portal.st-andrews.ac.uk/en/publications/e373626e-1e77-4cae-95dd-7db1fbc43939

Sperm whale habitat preference is still poorly known in the Mediterranean, despite the population being classified as ‘Endangered’ by the IUCN. Techniques to make the best use of various data sources are important in improving this situation. This work provides a detailed evaluation of sperm whale distribution and habitat use around the Balearic Islands using a novel analytical framework that combines transect and follow data while accounting for any autocorrelation present. During dedicated research cruises(2003-2008),sperm whales were located by listening at regular intervals along a search track, and subsequently followed acoustically.Sperm whales were encountered 56 times and followed for periods ranging from a few hours to three days. Logistic Generalized Additive Models were used to model the probability of whale presence across the study area as a function of environmental variables, and Generalized Estimating Equations were used to account for autocorrelation. The results suggest that sperm whales do not use the region uniformly, and that topography plays a key role in shaping their distribution.Moreover, single individuals were found to use the habitat differently from groups. This segregation appeared to be driven by water temperature and might reflect different needs or intraspecific competition. By shedding light on sperm whale habitat preference in such a critical area, this study represents an important step towards the implementation of conservation measures for this population.