for National Geographic News
This story is one of a series looking at National Geographic Crittercam research. Crittercam is a research instrument worn by wild animals and equipped with a video camera and other information-gathering equipment. Crittercam is used on animals both in the ocean and on land.
To learn more about the Crittercam's field test in Alaska, tune in to the Crittercam: Humpback Whales episode on the National Geographic Channel in the United States on Saturday at 8 p.m. ET. Got a high-speed connection? Click here to watch previews of the Crittercam television documentaries on the National Geographic Channel Web site.
When the normally placid waters of Alaska's Chatham Straight begin to bubble in a violent boil, marine biologist Fred Sharpe slips up to the cauldron's edge for a front row seat. He knows a coordinated feeding frenzy of epic proportions has just begun.
The bubbles are blown by a humpback whale (Megaptera novaeangliae) circling about 45 feet (14 meters) below the ocean surface as several of the whale's mates scream and wave their pectoral flippers in an effort to ensnare herring (Clupea pallasi) in the net of bubbles.
Moments later, in a highly-coordinated act, the whole pod will lunge to the surface through the center of the net with their jaws agape in hopes of a meal.
Sharpe, founder of the Seattle, Washington-based Alaska Whale Foundation, and his colleagues have been studying this feeding behavior for 18 years as part of a broad effort to conserve the humpbacks, an endangered species.
The researchers have employed sonar imaging, genetic analysis, computer simulations, and a host of laboratory experiments in their quest to understand the behavior, but until they attached cameras to 16 of the humpbacks, they had never witnessed the spectacle from an underwater perspective.
"You can do all the experiments you want, but to actually see one of those sardines engulfed by a whale is spectacularand informative," said Sharpe.
The footage, which adds insight to Sharpe and his colleagues' years of research, airs Saturday on the National Geographic Channel special Crittercam: Humpback Whales.
Among the key insights provided by the footage is a better understanding of the whale's feeding habits and requirements, said John Calambokidis, a biologist and co-founder of Olympia, Washington-based Cascadia Research, a group that studies marine mammals.
"Because some of the greatest threats to humpbacks would be their food supply, it is valuable to understand what they feed on and what conditions are required for them to effectively capture their prey," he said.