Group Count Estimates and Analysis of Surfacing Behavior of Beluga Whales from Aerial Video in Cook Inlet Alaska 1994

From these aerial videotapes, collected during aerial survey work in Cook Inlet, Alaska, from June 1-5, 1994, thirteen whale groups were counted to correct counts made by airborne observers. These correction factors were then used in the abundance estimate in Hobbs et al. (this report). In addition, the aerial videos provided the time that whales spent at the surface (190 whales were measured from five different groups), a variable in the correction for whales under the surface during a count. The color and size of whales on the monitor screen were also measured (155 from three groups). Surface times were not significantly different between two passes of the same whale group for all three color categories, but were significantly different for two of the three color categories between whale groups. The surface times of the different color groups were compared to surface times of different color groups measured in videotape taken during vessel work. Surface times measured from the vessel were significantly different from one aerial group, but not from another. The proportion of color groups was also compared to the proportion of color groups from a photograph of a stranded beluga whale group. There was a similar proportion of gray animals in the aerial video and in the stranding photograph. Because of this and because surface times were not shorter than measured in the vessel video, it appears that all or most whales are being counted in the aerial video. However, because these results are based on small sample sizes, and comparisons are made between very different views of whales, more analysis needs to be done before we can be confident about the proportion of whales that are seen in the aerial video.