Observers recorded species, time of sighting, and number in group. A group of belugas was defined as two or more individuals moving in the same direction and at the same rate, or within approximately five body lengths of each other (Norton and Harwood, 1985). For

each sighting, observers independently mTOR inhibitor recorded information on number in group, time of sighting, relative size and colour of whale (e.g. white [adult], large gray [subadult], small gray [“calf”, either young-of-the-year or one year old], behaviour (e.g., tail splashing; calf lying on mother’s back). A sighting consisted of either an individual whale or a group of whales. To ensure a consistent and uninterrupted search, there were no departures from the transect lines to circle groups of beluga that were sighted. Sighting locations selleck products were determined on the basis of elapsed time and aircraft speed, and in later years (1985, 1992) using the aircraft’s Global Navigation System (GNS) to record

geographic location of sightings. At the beginning and end of each transect, observers recorded the time (min, s) using synchronized digital watches, transect number, direction of flight (compass points), seat position, glare levels (nil, moderate, strong, forward or back) and sea state according to the Beaufort Scale of Wind Force. Audio tapes were transcribed to data sheets after each survey. We reviewed sighting conditions and transect coverage from 169 subarea surveys, selecting 77 of these for inclusion in our basic dataset (Table 1, Fig. 3). These met our criteria of having been completed without interruption in survey coverage or progression, and were rated by observers as having been flown under ‘good’ or ‘excellent’ survey conditions (Fraker et al., 1979 and Norton and Harwood, 1986) (seas were calm or near-calm with no whitecaps, sea states of 0–2 on the Beaufort Scale of Wind Force) (DeMaster et al., 2001) and full visibility (e.g., no fog or low cloud that obstructed visibility in any way on either side of the aircraft). Sightings from the subareas

were MRIP then pooled into four time periods; early (June 26–July 9), mid (July 10–20), late (July 21–31) and early August (Aug. 1–9). Whale counts, calf counts, and group sizes, were tabulated by time period, subarea (bay) and year using SAS V.8 (1990). Subarea surveys flown in each time period and subarea were pooled, to achieve adequate sample sizes. Two spatial methods were used to statically assess beluga distribution, both independent of survey effort. The extent and degree of clustering was examined using the Ripley’s L function, and the identification of ‘hot spots’ was done using kernel density estimates (KDE), and the calculation of Percent Volume Contours (PVCs) by time period ( Silverman, 1986, Worton, 1989 and Wand and Jones, 1995).