FIELD STUDIES OF WHALES AND DOLPHINS IN FAXAFLÓI BAY, SOUTH-WEST COAST, ICELAND
Although white-beaked dolphins (Lagenorhynchus albirostris) have been studied in Icelandic waters (Rasmussen, 1999; 2004; Magnusdottir, 2007; Bertulli, 2010), there is insufficient data to fully understand their abundance, population dynamics, habitat use and behaviour. Most studies have been conducted on the acoustics of white-beaked dolphins (Rasmussen & Miller, 2002; Rasmussen et al., 2002; Rasmussen et al., 2004; Rasmussen et al., 2006).
In the north of Iceland, L. albirostris are routinely found in Skjalfandi Bay. In the south-west of Iceland, sightings have been reported from Faxafloi and from the west coast of Iceland. The east coast of Iceland remains un-surveyed. Observations from previous Icelandic field seasons revealed that significant numbers of white-beaked dolphin are present in Icelandic coastal waters year round (Salo, 2004; Magnusdottir, 2007). The likelihood of detecting white-beaked dolphins was much higher in Faxafloi than in Skjalfandi at the NE-coast of Iceland during the whale-watching seasons (from April to October).
Observations by Rasmussen (1999) during the 1997 to 1998 whale-watching season in Faxafloi, showed the greatest abundance of white-beaked dolphins in June, July and August. Bertulli later confirmed high frequency of L. albirostris sightings occurring from May to August (Bertulli, 2010).
Aerial surveys have been conducted to estimate the abundance of white-beaked dolphins in Icelandic waters, using large scale surveys during the summer months (NASS survey conducted from 1986-2001) resulting in an estimated 31653 animals in 2001 (95% CI:17679–56672) (Pike et al., 2009).
In 2004 two images of a white-beaked dolphin (one taken off the coast from Olafsvik in Brei?afjor?ur and one in Skjalfandi) were well matched indicating that it was the same individual in both locations (Tetley, 2006). Three individuals were re-matched between Faxafloi and Skjalfandi in 2010 (Bertulli, 2010) and up to eighteen individuals were confirmed during additional analysis (Bertulli et al., in prep). In August 2006 one male white-beaked dolphin captured in Faxafloi was tagged with a satellite transmitter, recording movements (Rasmussen et al., 2007). That individual travelled numerous times between Faxafloi, Brei?afjor?ur and the Westfjords between August and January. On one occasion the tagged dolphin ventured as far as the Westman Islands.
The photo-identification performed between 1998 and 2010 and the information gathered from the single satellite tagged dolphin suggest that white-beaked dolphins in Icelandic waters inhabit coastal territories of relatively large scale, which they constantly scout. Based on information from the satellite track, one of these territories might extend between the south-west and north-west coast of Iceland.