sperm whales: a 2000 km journey across the mediterranean sea

A brand new paper on sperm whales’ movement across the Mediterranean Sea basin has just been published in the Deep Sea Research Part I journal. Following the unusual mass stranding of sperm whales in the Gargano peninsula, southwestern Adriatic sea, occurred in 2009, researchers have been able do identify and recognize some of them and to find out, through a collaboration of different research organizations, that the animals were previously encountered in the Ligurian Sea (NW Mediterranean) and in the Hellenic Ionian Sea. These findings provided for the first time new insight in male sperm whales’ movement patterns across the Mediterranean basin.

A. Frantzis, S. Airoldi , G. Notarbartolo di Sciara , C. Johnson , S. Mazzariol. Inter-basin movements of Mediterranean sperm whales provide insight into their population structure and conservation. Deep-Sea Research I 58 (2011) 454–459

The sperm whale is one of the very few deep diving mammal species in the Mediterranean Sea. Following a rare mass stranding of male sperm whales in the Adriatic Sea in December 2009, photo- identification methods were used in order to investigate previous sightings of the stranded whales in the region. Fluke photos of the stranded whales were compared with those of 153 and 128 free-ranging individuals photographed in the western and eastern Mediterranean basins, respectively. Three out of the seven stranded whales had been previously photo-identified and some of them more than once. To reach the stranding place, two of these re-identified whales performed long-range inter-basin move- ments of about 1600–2100 km (in a straight line) either through the Strait of Sicily or the Strait of Messina. In addition, comparisons among all whales photographed in the two Mediterranean basins revealed that one more individual first photographed in the western basin (1991) was re-identified 13 years later in the eastern basin (2004). These three cases provide the first conclusive evidence of inter- basin movement of sperm whales in the Mediterranean Sea. Inter-basin gene flow is important for the survival of the small and endangered Mediterranean sperm whale population. Mitigating the disturbance created by human activities in the straits area is crucial for its conservation..


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