Aerial Survey of Belugas in Cook Inlet Alaska August 2011
Aerial survey of the beluga population in northern Cook Inlet, Alaska, August 9-11, 2011, to obtain high-resolution video of each group of belugas to determine age structure and number of calves.
NOAA Fisheries conducted an aerial survey of the beluga population in northern Cook Inlet, Alaska, 9-11 August 2011. The goal of the surveys was to obtain high-resolution video of each group of belugas to determine age structure (white relative to gray individuals and dark gray calves) and number of calves. The survey (12.3 hours total) covered the coastal areas north of Point Possession and Beluga River. Consistent with previous surveys by NOAA Fisheries made each year since 1993, the August 2011 survey was flown in a high-wing, twin-engine aircraft (AeroCommander 690 N222ME) at an altitude of 244 m (800 ft) and a speed of 185 km/hr (100 kt). The survey track paralleled the coast (1.4 km offshore) and surveys occurred during the low tide when possible.
Beluga groups were found in the Susitna delta (from the Beluga River to the Little Susitna River) and in Knik Arm every day. On the 9 August survey, we video-taped and/or counted 5 beluga groups: two groups traveling from Susitna River toward the Little Susitna River (median counts = 13 and 158), a group in the mouth of the Little Susitna River (median count = 19), a group traveling from the Little Susitna River toward Point Mackenzie (median count = 18), and a group in Eagle Bay headed toward Eagle River (median count = 9) for a total median count of 204. On the 10 August low tide, we coordinated efforts with LGL’s boat-based photo-identification project and joint base Fort Richardson/Elmendorf Eagle Bay survey team, counting and video-taping a beluga group then alerting the teams to the group to begin their photo-id effort after we departed the area to find another group. Belugas were again in Eagle Bay (median count = 25) and the Little Susitna River (median count = 41), and along the east tributary of the Susitna River (possibly as many as 4 groups).
Unfortunately, due to groups traveling rapidly back and forth across the Susitna River mudflats, merging and splitting and concern of repeat sampling of groups, a total median count was not calculated for 10 August. On the 11 August low tide, we videotaped and/or counted 6 beluga groups: three along the Susitna River mudflats (median counts = 7, 57 and one large, rapidly travelling group), one large group milling west of the mouth of the Little Susitna River, one small group swimming toward Point Mackenzie (median count = 4), and one group in Eagle Bay (median count = 55). Median counts of the larger groups were potentially compromised by whale behavior (i.e., rapid swim speeds, multi-directional surfacing), therefore, a total median count for the day will await analyses of the video. We saw no belugas in Chickaloon Bay or Turnagain Arm during this survey.
The median estimate of belugas seen on 9 August 2011 (a quick index of relative abundance not corrected for missed whales) was similar to counts in 2010 (128 on 17 August, 154 on 18 August, and 266 on 19 August), 2009 (196 on 11 August, 212 on 12 August, and 197 on 13 August), 2008 (109 belugas on 12 August, 177 on 13 August, 194 on 14 August), 2007 (181 belugas on 1 August, 141 belugas on 2 August), 2006 (126 belugas on 16 August, 143 belugas on 17 August), and 2005 (236 belugas on 11 August, 277 belugas on 12 August).