SC/49/SM20 AERIAL SURVEYS OF BELUGA WHALES IN COOK INLET, ALASKA

• Main Authors: David J. Rugh, Roderick C. Hobbs, Kim E. W. Shelden, Janice M. Waite
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1997
• Subjects: Beluga; Beluga whale; Beluga Whale Committee; Beluga*; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.230.3758; http://alaskafisheries.noaa.gov/protectedresources/whales/beluga/survey/june1997.pdf

The National Marine Mammal Laboratory (NMML), in cooperation with the NMFS Alaska Regional Office, the Alaska Beluga Whale Committee (ABWC) and the Cook Inlet Marine Mammal Council (CIMMC), conducted an aerial survey of the beluga whale population in Cook Inlet, Alaska, during 8-10 June 1997. This provided a thorough coverage of the coasts around the entire inlet (1,388 km). Therefore, 100 % of the coastal areas where belugas were expected to be during this season were searched one or more times. The 23 hr survey was flown in a twin-engine, high-wing aircraft at 244 m (800 ft) altitude and 185 km/hr (100 kt) along a trackline 1.4 km from shore. Throughout most of this survey, a test of sighting rates was conducted with multiple independent observers on the coastal (left) side of the plane, where virtually all sightings occur. A single observer and a computer operator/data recorder were on the right side. After finding beluga groups, a series of aerial passes were made to allow at least two pairs of observers to make 4 or more counts of whales. The sum of the aerial estimates (using median counts from each site, not corrected for missed whales) ranged from 217 to 264 whales, depending on survey day. Only 1 beluga whale was found in lower Cook Inlet, 51-73 were counted near the Susitna River, 139-161 were seen in Knik Arm and 26-29 were counted in Chickaloon Bay. Combining data from 1994-97, almost half (46%) of the initial sightings occurred>1.4 km from the aircraft- the perimeter of the standard viewing area- with mean sighting distances of 1.2 km for small groups (<20 whales) and 1.9 km for larger groups (> = 20). In only 8 of 59 instances were whale groups>1.4 km from the trackline. Of 106 groups recorded by paired, independent observers in 1994-97, 20 were reported by only one primary observer, while 86 (81%) were reported by both observers.