Report casts killer whales as villains of seas


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Posted by . on December 14, 2003 at 08:27:14:

Report casts killer whales as villains of seas
THEORY: Biologists disagree about orcas decimating populations.

By DOUG O'HARRA
Anchorage Daily News

(Published: December 14, 2003)

The U.S. Senate report on the multibillion-dollar appropriations bill last month held this extraordinary directive:

Along with its regular work advising the government, the federal Marine Mammal Commission was to review evidence "that rogue packs of killer whales" are wiping out discrete populations of the most endangered marine mammals.

The provocative wording reflects an emotionally charged theory of Alaska killer whales that has divided scientists while capturing headlines and imaginations across the country.

The theory serves up a cinematic, tooth-and-flipper explanation for the catastrophic crash of Steller sea lions from the western Gulf of Alaska through the tip of the Aleutian Chain.

With the shock of a black-and-white orca breaching from the sea, the controversy has publicized a hypothesis that predators -- not a lack of food, overfishing, pollution or some mysterious change in ocean ecology -- may have caused a population crash of sea lions, otters and seals over the past three decades.

Killer whales started going after these marine mammals, the theory goes, after commercial fleets nearly wiped out sei, fin and sperm whales in the decades after World War II. Without these great whales as food, Alaska's orcas had to fill their bellies with smaller animals, triggering profound changes across the sea.

This idea has set off a big argument among marine biologists. The controversy gets discussed in low voices in hallways outside meetings, has burned up e-mail bandwidth, and has turned cocktail parties ugly.

The topic is scheduled to open the international Biennial Conference on the Biology of Marine Mammals on Monday morning, with opposing sides appearing before 1,500 scientists and students at a convention center in Greensboro, N.C. Scientists say there's talk of point-counterpoint articles appearing in marine mammal journals.

Many of the North Pacific's whale biologists say that they have serious problems with the theory, that it's often directly contradicted by their field observations.

"We question whether large whales were ever a large portion of (marine mammal-eating) killer whale diet," said conference presenter Paul Wade, a whale biologist at the National Marine Mammal Laboratory in Seattle. "We think that this first premise that this all happened due to whale removal is just wrong."

The nationwide news coverage last month followed by the Senate's reference to rogue killer whales has alarmed Homer biologist Craig Matkin, the state's leading killer whale researcher. For the past two years, Matkin has coordinated teams gathering basic biology of killer whales from Unimak Pass to Sitka Sound.

"A theory has been proposed, and before there's really adequate support, the effects are spinning out of control," he said recently. "It's been taken as a given, and it's simply a theory. There's great debate as to whether there's real evidence for it, and yet it's beginning to direct how the Senate appropriates funding."

But several of the whale-predation paper's eight co-authors say they're equally amazed at the reception they've received for what they say is a legitimate idea worth testing.

Jim Estes, an ecologist with the Center for Ocean Health with the U.S. Geological Survey in Santa Cruz, Calif., said the paper was difficult to get published even though many scientists found the premise and reasoning compelling.

Some pre-publication reviews of the paper were like "nosebleeds," Estes said. "But it wasn't until our paper came out that people seemed to go berserk.

"It's really befuddling to me that this jerked so many people's chains," he added. "We wanted to get people interested and excited about the possibility, and I think I was being horrendously naive."

"I'm not surprised that a lot of people are interested and thinking about this, and I'm not surprised that a lot of people don't believe it," added oceanographer Alan Springer at the University of Alaska Fairbanks, the paper's lead author.

"What I am surprised at is the hostility that this seems to have aroused in people," he said.

Here's the theory: The midcentury commercial catch of half a million great whales in the North Pacific triggered an ecological chain reaction that cascaded from the top of the marine ecosystem to the bottom, according to an article published in October in the Proceedings of the National Academy of Sciences. The idea builds on earlier work by Estes, Springer and others.

Deprived of the large fin, sei and sperm whales as food, Alaska's orcas then had to switch from big meals to small ones, targeting harbor seals, then northern fur seals, followed by Steller sea lions and finally sea otters.

The paper charted whale harvests across the region and argued that the four smaller marine mammal species declined in sequence after the big whales were taken out. Marine mammal physiologist Terrie Williams of the University of California at Santa Cruz calculated how many sea lions or sea otters or harbor seals a killer whale must consume to get the 160,000 to 240,000 daily calories it needs to survive, and modeled the effects.

The conclusion was startling, Williams said. A relatively small change in diet by hundreds of killer whales, or a big change in the habits of as few as five animals, could explain dramatic population declines across the region.

The western stock of sea lions has been listed as endangered since 1997. Protecting them has led to expensive closures in a $2 billion commercial fishery. The search for reasons behind the decline involves a $100 million scientific investigation by more than 130 researchers at a dozen institutions.

Sea otters west of Kodiak Island have also crashed, and the U.S. Fish and Wildlife Service has been considering whether that population must be listed as threatened or endangered. Last week, it was sued by conservation groups for taking too long to make a decision.

Sea lion researchers have been investigating lack of food, competition with fisheries, disease, contaminants, physiological problems and predation as possible explanations. No one has figured it out yet.

Finding an answer, especially one that shifts responsibility away from fishing and toward charismatic killer whales, would generate a cascade of its own. In Alaska, where several of these distinctive 10-ton predators have been given names, the reaction might become personal.

That an entire marine food web could be altered from the top down by predators instead of from the bottom up by shifts in food contradicts the dogma about how marine populations change, Springer said. But it might explain the disappearance of sea lions better than other theories.

Williams has received hate e-mail. "I'll be in an argument with someone, and I'll suddenly realize that they haven't read the paper," she said.

Some people have mistakenly assumed the paper condemns killer whales or takes commercial fishing "off the hook" for declines, she added.

"Predation has to be considered a factor in everything that's going on," she said. "And the paper also says if you remove a large amount of biomass, whether through whaling or commercial fishing, you're going to have a long-term ecological consequences."

But whale biologists like Matkin and Wade say they have grave problems with the paper and how the authors interpreted the evidence. Several scientists have argued that harbor seals, northern fur seals, sea lions and otters didn't really decline in sequence across the region, that Alaska's killer whales don't switch prey in the way the paper describes and didn't face significant food shortages after the great whales were removed.

Southeast Alaska contains higher numbers of marine-mammal-eating killer whales than the Aleutians but never experienced comparable declines in sea lions or otters.

Two decades of studies in the Gulf of Alaska have found scant evidence that killer whales eat many sea lions, though a few specific whales appear to do so regularly. But both sides agree that little is known about what killer whales really do in the ocean off Alaska, especially out the Aleutian Chain.

"The reason we're in this moment is because there hasn't been enough field work," Matkin said. "The bottleneck is not having enough people out there looking and studying and watching. It's hard-fought information."

With two such strong viewpoints, conference organizers at the Society of Marine Mammalogy decided they couldn't have only one side presented.

"It was just too emotional and controversial," said science program director Aleta Hohn, a biologist at the Southeast Fisheries Science Center in North Carolina.

In the first session of the five-day conference with biologists from around the world, Williams and Estes, a married couple in civilian life, will have 25 minutes to present their theory. Wade, representing 14 co-authors that include Matkin and Alaska Department of Fish and Game marine mammal coordinator Bob Small, will have 25 minutes to present a different view. Each will have five minutes to respond.

Hohn hopes the 1,500 people in the audience will keep the debate going all week.

"I think this is a fabulous opportunity for students and young professionals to see that there are differences of opinion in science, that science is a process," she said. "We don't always agree."

As for the Marine Mammal Commission looking into "rogue packs of killer whales," scientists on both sides took issue with that wording.

"This is not furthering due scientific process," Matkin said. "This is inciting."

"To call these animals rogues seems ridiculous," Estes added. "They're predators. They eat things."

The Senate's instructions on the topic came from the subcommittee that oversees funding for the departments of Commerce, Justice, State and Judiciary, said Melanie Alvord, communications director for the Senate Appropriations Committee.

Alaska Sen. Ted Stevens, appropriations chairman and a member of the subcommittee, did insert his own directions for the National Marine Fisheries Service in the report, asking the agency to keep investigating whether killer whales have been eating sea lion pups, Alvord said.

"I can tell you that Senator Stevens is concerned about these pods and what they're doing and the fact that it seems like they're attacking animals," said press secretary Courtney Schikora.

If it remains in the final bill approved in Congress, the commission will "get the guys who wrote the paper together with some of the doubters, and we'll have them sit down in a workshop someplace," said executive director David Cottingham. "That's what we do."

Daily News reporter Doug O'Harra can be reached at do'harra@adn.com.



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