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Summer social distribution of sperm whales (Physeter macrocephalus) in the Mediterranean Sea

Published online by Cambridge University Press:  24 May 2004

Violaine Drouot
Affiliation:
Centre de Recherche sur les Cétacés, Marineland, 306 Avenue Mozart, Antibes, France GREC, 741 Chemin des Moyennes Bréguières, BP715, 06600 Antibes Cedex, France Institute of Environmental Science, University of Wales, Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd, Wales, LL57 2UW, UK
Alexandre Gannier
Affiliation:
Centre de Recherche sur les Cétacés, Marineland, 306 Avenue Mozart, Antibes, France GREC, 741 Chemin des Moyennes Bréguières, BP715, 06600 Antibes Cedex, France
John C. Goold
Affiliation:
Institute of Environmental Science, University of Wales, Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd, Wales, LL57 2UW, UK

Abstract

Sperm whale social distribution was investigated in the Mediterranean Sea, using data collected during summer surveys from 1997 to 2002. Variations in the size of sperm whale schools/underwater aggregations were assessed using both visual and acoustic data. Individual body lengths were estimated acoustically, using the click inter-pulse intervals. Regional comparisons were undertaken, taking the 41° parallel as a north/south boundary. In the southern region, schools of up to seven sperm whales were sighted and calves were relatively frequent. The animals ranged between 8·6 m and 13·1 m long. In the northern region, school sizes were significantly smaller, with a maximum of three whales sighted at the surface. However, the acoustic survey showed that sperm whales form loose aggregations of up to five animals in certain areas. Whales detected in the north were 12·6 m long on average, and the body size range was relatively small. This summer survey demonstrated a segregation of males, in the north, from larger schools including calves, which seemed to be confined to the southern region.

Type
Research Article
Copyright
2004 Marine Biological Association of the United Kingdom

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