Aerial Survey of Belugas in Cook Inlet Alaska August 2009
Aerial survey of the beluga population in northern Cook Inlet, Alaska, August 11-13, 2009 to obtain high-resolution video of each group of belugas to determine age structure and number of calves and to compare results with boat-based photo-identification surveys conducted by LGL Alaska Research Associates, Inc.
NOAA Fisheries conducted an aerial survey of the beluga population in northern Cook Inlet, Alaska, 11-13 August 2009. 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 and to compare some of these results with boat-based photo-identification surveys conducted by LGL Alaska Research Associates, Inc. The survey (15 hours total) covered the coastal areas north of Point Possession and Beluga River. The survey was flown in a high-wing, twin-engine aircraft (AeroCommander 680FL, N98UP) 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) each day and crossed Cook Inlet from Point Possession to Beluga River. Two flights occurred each day on 11 and 12 August; a full survey of the upper inlet in the morning to locate groups and an afternoon survey of the upper inlet that coincided with the low tide, when belugas are typically found in consolidated groups.
On 13 August, both flights coincided with the high tide as the low tides were too early and late in the day to permit adequate light levels for videotaping. We found beluga groups in the Susitna delta (from the Ivan to the Little Susitna River) and in Knik Arm every day. On the 11 August low tide survey (second flight of the day), we videotaped and counted belugas along the mudflats of the eastern tributary of the Susitna River (median count = 85 whales), in the Little Susitna River (median count = 89 whales), and in Eagle Bay in Knik Arm (median count = 22 whales) for a total median count of 196 whales. On the 12 August low tide, we videotaped and counted belugas in the Little Susitna River (median count = 161 whales), and in Knik Arm near Eagle Bay (median count = 51 whales) for a total median count of 212 belugas. On 13 August, we coordinated efforts with LGL’s boat-based photo-identification project, counting and videotaping a beluga group then directing the LGL boat to the group to begin their photo-id effort after we departed the area to find additional beluga groups. We found belugas in the same areas as the previous high tide surveys: in Knik Arm near Birchwood Airport (median count = 27 belugas), in the mouth of the Ivan River (median count = 61 belugas), in the eastern tributary of the Susitna River (median count = 15 belugas) and in the Little Susitna River (median count = 94 belugas) for a total median count of 197 whales. We did not find belugas in Turnagain Arm and Chickaloon Bay during the entire August survey. The median estimates of belugas seen each day in August 2009 (a quick index of relative abundance not corrected for missed whales) were greater than those documented in August 2006-2008, but less than those in August 2005.