At first we might see just a few spouts on the horizon. Then quickly we move among them, keeping a distance of a hundred metres so as not to bother them, explained project co-director Erich Hoyt of the Whale and Dolphin Conservation Society , which provided the majority of funding for the project.
As far as the eye can see, in every direction you see groupings of two to six killer whales surfacing, spouting then dipping below the surface.
Each grouping has a focal mother figure surrounded by her offspring, some of whom may be full grown males with up to 2m dorsal fins that tower over the females, he says.
They also used a special underwater directional microphone called a hydrophone to record the sound of the killer whale vocalisations.
Each pod of fish-eating killer whales in the Avacha Gulf has a specific vocal dialect which could be pinpointed by the hydrophone, while individual killer whales can also be identified by the shape of their dorsal fins and markings.
That allowed the scientists to analyse the killer whales behaviour.
The whales rarely forage and feed when they gather into a much larger superpod, the scientists found.
That suggests they do not gather to herd fish or increase their foraging success. In fact, say the scientists, depending on the type of prey, a superpod might have the effect of decreasing the feeding success of each whale making it unproductive to feed in large groups.
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