Ecological niche of three teuthophageous odontocetes in the northwestern Mediterranean Sea

E. Praca (1, 2) , A. Gannier (3)

1 Centre de Recherche sur les Cétacés
2 Oceanology Laboratory
3 Groupe de Recherche sur les Cétacés

In the northwestern Mediterranean Sea, sperm whales, pilot whales and Risso's dolphins prey on cephalopods exclusively or preferentially. In order to evaluate their competition, we modelled their habitat suitability with the Ecological Niche Factor Analysis (ENFA) and compared their ecological niche using a discriminant analysis. We used a long term (1995–2005) small boat data set, with visual and acoustic (sperm whale) detections. Risso's dolphin had the shallowest and the more spatially restricted principal habitat, mainly located on the upper part of the continental slope (640 m mean depth). With a wider principal habitat, at 1750 m depth in average, the sperm whale used a deeper part of the slope as well as close offshore waters. Finally, the pilot whale has the most oceanic habitat (2500 m mean depth) mainly located in the central Ligurian Sea and Provençal basin. Therefore, potential competition for food between these species may be reduced by the differentiation of their ecological niches.

Domaines: Océan, Atmosphère

E. Praca, A. Gannier. Ecological niche of three teuthophageous odontocetes in the northwestern Mediterranean Sea. Ocean Science Discussions, 2007, 4 (5), pp.785-815. ⟨hal-00331134⟩