Cetacean distribution in the western Ligurian Sea

Arianna Azzellino, researcher with the Milan Politecnico and with Tethys, together with other colleagues, have recently published "Habitat use and preferences of cetaceans along the continental slope and the adjacent pelagic waters in the western Ligurian Sea".

The work is based on research done between 1996 and 2000 in a study area of 3000 Km squared within the Pelagos Sanctuary.

Researchers reported a total of 814 sightings of striped dolphins, fin whales, sperm whales, long-finned pilot whales, Cuvier's beaked whales, Risso's dolphins, common bottlenose dolphins and short-beaked common dolphins. Sighting data were integrated with a Geographic Information System to a set of environmental characteristics, which included bottom gradient, area between different isobaths, distance from the coast etc.

The study showed interesting results: 1) differences in the habitat preference of most species; 2) habitat segregation between Risso’s dolphins, sperm whales and Cuvier’s beaked whales; 3) temporal segregation in the use of the slope area for sperm whales and Risso’s dolphins; 4) generic preference for the pelagic area for fin whales, common dolphins and pilot whales; and 5) no specific habitat preference for striped dolphins, but a relation between their group size and habitat use.

Last but not least, all the regular species showed interannual and seasonal movements, indicating that changes in the environmental and climatological conditions have a remarkable influence on habitat use.

Arianna Azzellino and Silvia Bonizzoni

---
Azzellino A., Gaspari S., Airoldi S., Nani B. 2008. Habitat use and preferences of cetaceans along the continental slope and the adjacent pelagic waters in the western Ligurian Sea. Deep-Sea Research I 55: 296–323.