| Summary: | The preservation of the biodiversity is nowadays one of the most difficult challenges for conservation biologists, as an increased number of species has been threatened or overexploited in the last years. Demography, “the science of the populations”, can furnish useful tools to improve natural population management and conservation. The knowledge of life-history traits and demographic parameters is needed to develop demographic models; these models, based on life-history tables and transition matrices, are essential to foster population conservation, as they allow to assess population performance, project population trends overtime and then suggest specific measures for their protection. This is mostly meaningful with long-lived and slow reproducing species, as cetaceans, threatened by many sources of mortality and environment stress. Nevertheless, few studies deal with the demography of these marine mammals because of the difficulty in collecting this kind of data, thus the main cetacean life-history traits are still largely unknown, especially in the Mediterranean Sea. The aim of my PhD thesis is to improve the demographic knowledge on Mediterranean fin whale (Balaenoptera physalus Linneaus 1758) and bottlenose dolphin (Tursiops truncatus Montagu, 1821), analyzing stranding and photo-identification data. The most exhaustive long-term photo-identification dataset available for the Mediterranean fin whale, recorded by Tethys Research Institute in the Pelagos Sanctuary over 1990-2007, was analyzed in order to obtain demographic information on the only mysticete regularly occurring in our basin. The analysis of the annual encounter rate revealed an uneven occurrence of the fin whale across the years and months: an anomalous reduction between 2001 and 2004 and a higher abundance of the target species in the Corso-Ligurian Basin in late-spring and summer were observed. Using the photo-identification technique, 431 different fin whales were recognized, 318 of known size: 6 calves (≤10 meters), 33 immatures (10-15 m), ...
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