Southeast Alaska Home To Special Pod Of Whales

Whale researcher Fred Sharpe would love to see humpback whales return to Puget Sound, but worries that modern life may have made the sound too inhospitable.

The humpbacks, some of which cooperate on elaborate efforts to trap krill or fish in nets they make out of bubbles, are one of the most endangered species of whale, said Sharpe, who recently founded the Seattle-based Alaska Whale Foundation.

The North Pacific humpback population, once estimated at 25,000, has dwindled to 3,000. The whales, Sharpe said, are one of the most fascinating species on the planet.

While most feed solo on tiny sea creatures, “like cows of the sea,” there is a small subgroup of humpbacks in southeast Alaska that work together as aggressive hunters. They demonstrate a social complexity uncommon for baleen whales, he said.

Whales either have baleen or teeth. Baleen whales feed by straining water through long, thin plates of baleen in their mouths. Tiny sea creatures such as krill are caught on the baleen.

The southeast Alaska humpbacks create “bubble nets” as they circle below and around krill or schools of fish, Sharpe said. The whales work together, blowing air out to encircle their prey in a cylinder of bubbles.

The whales gather below and then swim rapidly up from the bottom of the bubble net, gorging themselves on the catch and finally bursting out on the ocean surface.

While some other marine predators use bubbles to assist in foraging, Sharpe said the complexity and cooperation used by the humpbacks is unique.

“It’s fabulous and bizarre, and we don’t fully understand it,” he said.

Sharpe said the whales emit trumpet-like sonar calls while feeding, but it’s not clear if this is to coordinate the attack, intimidate the prey or establish dominance within the group.

“All we know is that they do use a lot of sound,” he said.

Another curious aspect of these humpbacks, he said, is that membership in the pods, or communal groups, doesn’t appear to be based on familial connections. Most animals that hunt in groups are related, Sharpe said, but preliminary genetic studies of humpback whales indicate that they form pods on some other basis.

This summer, the Alaska Whale Foundation will conduct its fourth year of study of the southeast Alaska humpbacks, seeking to answer some of these questions. Sharpe’s broader goal is to learn enough about these whales so people know enough to protect them and help them flourish.

“We’d love to see them return to Puget Sound,” he said.

“Most of the inland waters were depleted in the early part of the century,” Sharpe said Tuesday, noting that some whaling companies were based in Seattle and that hunting continued along the West Coast until the mid-1960s.

The depleted population may be extra-sensitive to human impacts, including commercial fishing, chemical pollution, acoustical pollution and even commercial wildlife-viewing ventures.

“There is evidence that some human activities, like loud sounds from large ships, could displace the animals from favored feeding areas,” he said.

Sharpe noted that the humpback only feeds four months out of the year.

“The rest of the year it fasts,” he said. After periods of “prolonged anorexia … when they get to Alaska and the snack bar opens, they don’t waste any time.”

Roger Payne, a whale expert who serves on the foundation’s board, said Sharpe’s investigations into the whales’ “interesting social structures and unusual use of feeding calls shows great promise in unraveling the mysteries of these creatures.”