Early this morning we came upon a lone humpback whale feeding with a "bubble net." A whale dives beneath a school of prey such as small herring, and then ascends in an upward spiral around the fish, releasing air from its blowholes. As these bubbles rise, they form a barrier to the fish - a sort of rising bubble fence. The fish react by swimming into a very tight ball. Schooling fish such as herring will swim into a very tight ball when startled. Normally, schooling behavior is effective protection; a predator is overwhelmed, unable to track one fish among thousands maneuvering together. But for the humpback, the effect is perfect. . . forty-ton whales prefer thousands of fish in a mouthful.
The waters were glassy calm so we could observe the process. What we saw was this: The whale dove, and within a couple of minutes, enormous bubbles rose to the surface. The bubbles were in a line, and as more bubbles appeared, the line curved in a clockwise direction. After a few more seconds the bubble line on the surface formed a complete circle. Just as the last large bubbles were rising, we saw the corner of the whale's left pectoral flipper near the middle of the bubble ring. A moment later, the whale's head came shooting up in the middle of ring, the enormous mouth open ninety degrees. It was spectacular to see. . . so spectacular, in fact, that many of us heard the early morning announcement, and rushed out of bed sleepy-eyed and bed-haired so as not to miss it. Coffee could wait! This was just amazing to watch.
