Trends In Cetacean Sightings Along The Galician Coast, NW Spain, 2003-2007, And Analysis Of Cetacean Habitat Preferences
Graham J. Pierce (1,2), Mara Caldas (3), Jose Cedeira (3), M. Begoña Santos (1,2), Alfredo López (3), A.F. Zuur (4), Mar Sacau (2), Ángela Llavona (3), Pablo Covelo (3), Gema Martinez (5), Jesus Torres (5)
(1) School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK; (2) Instituto Español de Oceanografía, Centro Oceanográfico de Vigo, P.O. Box 1552, 36200, Vigo, Spain; (3) CEMMA, Apdo. 15, 36380 Gondomar, Pontevedra, Spain; (4) Highland Statistics, 6 Laverock Road, Newburgh, Ellon, Aberdeenshire, AB41 6FN, UK; (5) Department of Applied Physics. Science Faculty. University of Vigo. Lagoas Marcosende, 36200, Vigo, Spain.
Since mid-2003, systematic monthly sightings surveys for cetaceans have been carried out in Galicia (NW Spain) from observation points around the coastline, with the aim of providing baseline data on cetacean distribution and habitat use to underpin future conservation measures. Here we summarize results for September 2003 to October 2007. The most frequently recorded species was the bottlenose dolphin (Tursiops truncatus), seen during 10.7% of observation periods, followed by common dolphin (Delphinus delphis, 3.7%), harbour porpoise (Phocoena phocoena, 1.6%), Risso’s dolphin (Grampus griseus, 0.4%) and short-finned pilot whale (Globicephala melas, 0.2%). The probability of sighting bottlenose dolphins was highest in the vicinity of Riveira, common dolphins were most frequently seen around Cabo Ortegal, Laxe and La Guardia, and porpoise sightings were most frequent in the far north (Ribadeo) and south (La Guardia) and around Fisterra. In terms of habitat preferences, bottlenose dolphins were seen to be associated with the most productive areas (areas with positive chlorophyll a anomalies) while both common dolphins and harbour porpoises were seen most frequently where the continental shelf is narrowest.