Sperm Whale

The sperm whale (Physeter macrocephalus) Mediterranean subpopulation was recently proposed for listing as endangered, following the criterion C2a(ii) which refers to “population size estimated to number fewer that 2500 mature individuals; a continuing decline, observed and projected in numbers of mature individuals and at least 95% of mature individuals in one sub population”.

capodoglio 02

capodoglio 04

In the study area the sperm whale’s presence was monitored since 1991. However, the IFAW detection acoustic system was set up only in 2004. As a consequence, the number of sightings raised significantly. Sperm whale’s residency and movements within the study area have been regularly investigated using photo-identification and data collected over a 8 years period (2003–2010). 

A total of 50 individuals were photo-identified on the base of their natural marks on the fluke. Scars and marks, on both sides of the animals, as well as the shape of the dorsal fin, where useful tools to complete photo-id recognition especially when matching was uncertain, this information was added to the catalogue when available. Data confirmed the presence of young males in the waters of the Canyon of Cuma, supporting the hypothesis that this area is relevant for all species, ages and classes, with groups formed by females and their offspring, lone males (bulls), and variable aggregations of young males.

capodoglio01

This type of association is poorly understood and previously had not been possible to document stable associations between immature males. The association we have documented over the years suggests that the social structure of the groups of non-breeding males may reflect that of the females, in terms of complexity and long-term relationships between individuals. Monitor the social structure and the state's population of sperm whales in the area therefore becomes important for the conservation of the species in the Mediterranean; a challenge for the protection of the sperm whale is represented by the proposed enlargement of the Marine Protected Area of Ischia in a SCI (site of community importance) that includes the entire system of the canyon of Cuma and the critical habitat of the species.