Humpback Whales Bubble Net Feeding
Whales Who Enjoy Solitude Come Together for Complex Feedings
Aug 11, 2009
Naturalist Tiffany Littleton spends up to 50 hours a week on a wildlife adventure boat full of tourists in Juneau, Alaska during the months of July and August. Tourists from all ends of the earth come to see majestic bald eagles, lazy sea lions, playful seals, adorable sea otters - but the big one that better not get away on this three hour tour is the whale.
All in a Whale Watching Tour Guide's Day's Work
"It is no doubt," Littleton explains, "everyone who takes the tour wants to see some whales. Fortunately in the surrounding waters of Auke Bay in these months we are able to find whales who are here to feed every day."
The Discovery of Bubble Net Feeding
Humpback whales are usually solitary beings. In the winter they migrate to warm waters to mate and give birth, fasting until summer when they may swim up to 4000 miles to cooler waters. Typically in these waters around the world an average-sized humpback whale will work alone and eat up to 4400-5000 pounds of krill, plankton, or herring twice a day storing up calories for the winter.
During the whale watching tour, Littleton proudly explains that an important discovery with humpback whales happened in Juneau. "In 1979, a high school teacher at Juneau-Douglas named Charles Jurasz was the first to observe and write about humpback whales using a cooperative feeding technique with complex bubble blowing. He called the technique 'bubble net feeding.' "
As a tour guide, Littleton has more experience than most with bubble-net feeding which usually occurs for two weeks every year. However, she admits it is thrilling every time. "There is nothing like watching the whales lunge straight out of the water with their mouths wide open, and sometimes you can even smell their fishy breath!" she shares. "I always watch for the sea gulls because they can see the whales working and know the herring will soon be jumping out of the water to escape the whales that have caught them in the bubble net and are chasing them. Wherever the sea gulls are swarming hoping to snatch one of those herring, that is where we tell the tourists to look. That is where the whales will lunge out of the water."
What is Bubble Net Feeding?
There is much to still be learned about bubble net feeding, but it has only been observed in Alaska, Antarctica, and on the west coast of South America. "It is estimated that only 1000 humpbacks know how to work together to do bubble net feeding," Littleton shares.
What is known is that a pod of humpbacks come together where there are schools of fish. One whale starts to blow an arc of basketball-sized bubbles close to the school of fish. Other whales sing songs and/or chase the fish into the arc, at which time the bubble blower completes the circle, thus forming the "bubble net." The whales make a thrilling lunge upward through the circle to the surface, filling their mouths with water and fish.
"The whales have a buccal cavity under their jaws full of pleats that can expand and take in an enormous amount of water and fish," Littleton explains. "They then force all the water out through their baleen and swallow only the fish. Their throats are surprisingly small, and can only swallow things as big as a grapefruit, so this definitely wasn't the whale that swallowed Jonah," she shares with a laugh.
2009 Bubble Net Feeding in Juneau
For an unknown reason, bubble net feeding lasted three weeks long in Juneau in 2009 instead of the typical two weeks. "Tourists this year have really been fortunate to have so many encounters with bubble net feeding," Littleton said. "I've heard it is more likely to be struck by lightning than to be able to come on a three hour tour and see bubble net feeding. This year has been a great year for our tourists."
All facts about humpback whales were researched on The Alaskan Whale Foundation Home Page.
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