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| Long-finned pilot whale | ||
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| Strait of Gibraltar | ||
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The Mediterranean long-finned pilot whale
Long-finned pilot whales Globicephala melaena in the Pelagos Sanctuary. Photo © Tethys Research Institute.
Estimates of abundance for the Mediterranean population are unavailable. Pilot whales on the Strait of Gibraltar have been estimated to number 260-270 animals (years 1999-2005). Population structure is also unknown. The working assumption is that two subpopulations are present in the Mediterranean, one in the Alborán Sea, and another in the Ligurian Sea.
Pilot whales are very common in the Alborán Sea and adjacent waters, but less common or infrequent elsewhere in the Mediterranean.
The long-finned pilot whale is a predominantly offshore species with a preference for deep waters seaward of the continental shelf and slope. Preferred habitats are generally deeper than 500 m, and often include waters of 1000-2000 m.
Diet is thought to include predominantly squids, but pilot whales may also occasionally eat pelagic fish. In the case of the Strait of Gibraltar, the species has a specialized diet in summer month, mainly based on squids, and a less specific diet in winter, with a mix of squids and fish.
Movements of pilot whales in the Alborán Sea seem to be cyclic. For instance the species may be resident in the Strait of Gibraltar and move to the area of Almería, in the Alborán Sea, at the end of spring / beginning of the summer, possibly for breeding purposes.
The social structure of pilot whales exhibits a hierarchical social system in which one population (for example the Alborán Sea subpopulation) encompasses several 'clans' (for example the one in the Strait of Gibraltar, including 260 individuals) composed of several 'pods' (with a mean of 15-20 individuals). Pods, in turn, appear to include several family groups, similar to killer whale matrilineal units or matrilines.
Owing to their offshore distribution, long-finned pilot whales are less exposed to human activities than more coastal cetaceans. Threats are poorly known, but likely include by-catch in pelagic fishing gear, collisions with vessels, man-made noise and the effects of accumulation of organochlorine and other contaminants. In the areas where their spatial distribution is close to the coast, they are usually exposed also to whale watching activities.
During the winter 2006-2007 pilot whales suffered from a morbillivirus epizootic, but there are no data about the effects of this epizootic.
For more information on Mediterranean long-finned pilot whales see:
Cañadas A. 2006. Long-finned pilot whale Globicephala melas (Mediterranean subpopulation). Pp. 23-28 in Reeves R.R., Notarbartolo di Sciara G. (compilers and editors). The status and distribution of cetaceans in the Black Sea and Mediterranean Sea. IUCN Centre for Mediterranean Cooperation, Malaga, Spain. (whole report: 2,752 Kb)
De Stephanis R., Verborgh P., Pérez S., Esteban R., Minvielle-Sebastia, Guinet C. In press. Social structure of long-finned pilot whales (Globicephala melas) in the Strait of Gibraltar. Acta Ethologica.
