Estimated Abundance of Belugas, Delphinapterus Leucas, in Cook Inlet, Alaska, from Aerial Surveys Conducted in June

The National Marine Fisheries Service (NMFS) conducted aerial surveys of the beluga, Delphinapterus leucas, population in Cook Inlet, Alaska, 31 May 9 June 2011 as a continuum of surveys conducted since 1993. Eight of the days in 2011 resulted in complete surveys of the beluga habitat in the upper inlet (north of East Foreland and West Foreland); and the remaining two days included surveys of the lower inlet. Beluga groups were dispersed by the last day of the survey (9 June) effectively excluding this day from the abundance analysis. During the remaining seven surveys of the upper inlet, 26 beluga groups were observed, and up to 12 counting passes were made per group. This season there was a fairly typical presentation of beluga groups, with two or more large groups in the Susitna area and a few smaller groups in Chickaloon Bay on each survey day. No beluga groups were found in Knik Arm, Turnagain Arm, or elsewhere in Cook Inlet. After excluding the 4 June survey because of a low estimate that was likely due to poor sighting conditions and dispersed groups, six complete surveys were considered to be of sufficient quality to use for estimation of abundance. The estimated abundance for June 2011 is 284 (CV 16%, 95% CI 207 to 389, Nmin = 248) with a ten-year trend (2001-2011) of -1.1% per year (SE = 1.1%). The trend since the management of the beluga hunt began in 1999 (i.e. 1999–2011) is -1.7% per year (SE = 0.9%).