Killer Acoustics

Austrian marine biologist to spend month collecting acoustical information on orcas

Posted: Sunday, May 30, 2004

Stalking silently through Southeast waters in search of prey, pods of "transient" killer whales have been eluding scientists for decades, often providing more questions than answers.

Volker Deecke, a marine biologist from Vancouver, British Columbia, by way of Austria, is hoping to collect some of that hard-to-get data by doing acoustical research while stationed at Point Retreat lighthouse during the month of June.

"The project that we're doing here, we're essentially trying to find out which is the better way to see how often killer whales use a certain area," said Deecke, who uses visual surveys as well as underwater audio surveys with hydrophones.

After finding out that Point Retreat would be an ideal location for his research on killer whales, also known as orcas, Deecke contacted the David Benton at the Alaska Lighthouse Association.

"I knew the people who were sponsoring his research," said Benton, who used to work in fisheries. "It was one of those small world things. We were really excited to help out."

Deecke, along with the help of two assistants, will operate two observer stations to scan Lynn Canal and Stephens Passage with binoculars for 10 minutes every hour. They will also be listening to two hydrophones, underwater microphones, which are installed at either side of Point Retreat, the northernmost tip of Admiralty Island.

"In good conditions you can hear them from 10 to 15 miles away, where as you can only see them on the ship probably two or three, maybe five miles if you're really lucky," he said. "And the other thing is acoustics works at night just as well as at day and you can get a whole lot of information from the animals because you can tell if whether they're transients, the mammal-eating killer whales, or the residents, the fish eaters."

Deecke said that his research is mainly emphasizing transient killer whales because they are more mobile and therefor have been more difficult to study in the past.

"Our point is that acoustics is a really powerful tool for learning about these animals," he said. "So what we're doing at the lighthouse is comparing both methods."

"And then we can determine, do we hear the killer whales before they see them, or vice versa, and that way we can find out which method is the more efficient one."

Deecke has also been coordinating with several well-known local marine biologists, including Jane Straley of Sitka and Dena Matkin of Gustavus, to pool information to further the research process.

"We're essentially working on different aspects of the same project," said Straley, who has been working on the Steller Sea Lion Project, a project studying the Steller sea lion predation by killer whales in Southeast Alaska.

"It's really difficult to see what they are eating," said Straley. "It's painfully slow to collect data."

"So far it seems like harbor seals are the predominant prey," she said, adding that transient killer whales prey on Dall's porpoises, Steller sea lions, and harbor porpoises. They have also been known to prey on minke whales, as well as gray whale calves.

Because transient and resident killer whales do not associate, scientist are able to identify which group they fall into by linking them by photos, acoustics, association and genetics, said Straley. Each individual orca is identifiable by it's dorsal fin and "saddle patch," a white marking behind the dorsal fin that looks much like a saddle for a horse.

"It's like they're different cultures," said Straley.

Genetic studies have been done on killer whales that determine transient and resident populations have not interbreed for extensive periods of time. They are also known to have different dialects, with residents being much more vocal than transients.

"Among the residence you find these vocal dialects where different family groups have different vocalizations," said Deecke. "The resident killer whales have a very interesting social structure where you have no, what we call, juvenile dispersal, and that means that both male and female offspring never leave their mother's group."

Deecke said some of the most fascinating information he has come across in his research is the meticulous hunting practices of the transient killer whales.

"Even the little calves that may be just a couple of months old, they're so disciplined, they're swimming beside their mother," he said. "They're not goofing off, they're just right in line. And then as soon as they make a kill pandemonium breaks loose and the animals often become vocal. Really loud, haunting vocalizations."

Deecke said they are so silent in their hunting because their prey have excellent underwater hearing.

"I find it fascinating how they manage to coordinate their behavior to that degree and then as soon as the kill is made everybody knows, OK now is the time to communicate, to vocalize, to show the play behavior in the calves."

There is not any conclusive evidence, but Deecke said each transient killer whale must eat about the equivalent of a harbor seal a day. He said there are roughly 100 transient killer whales that roam Southeast.

"So they're certainly having impacts on marine mammal populations and they need to have a good available food base in order to make a living up here,"

Deecke said the research is much more than the collection of factual data.

"We also need to learn a lot of things that have conservation implications. We need to know what is happening to the acoustic environment of these animals, and that's also a way that this project can help," he said. "These are acoustic animals. They find their food through echolocation, where they make clicks and they listen for the echoes to come back. They communicate using sound."

"Transients probably listen to sounds that their prey make," said Deecke. "And boat noise does have a distinct effect on that and that is something we need to be more aware of, is what are these boats doing to the whales acoustic environment."

Deecke said any help locals can provide about the location of killer whales is much appreciated. He is often standing-by on marine band channel 16 and can be contacted at (604) 377-7356. Straley can be contacted at (907) 738-6629 with any information on orcas.

• Eric Morrison can be reached at eric.morrison@juneauempire.com.



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