HOPKINS RESEARCHER STIRS UP WHALE OF A CONTROVERSY

Pacific Grove researcher Stephen Palumbi is at the center of an international debate over wildly different estimates of historic whale populations.

Palumbi, an evolutionary ecologist at Hopkins Marine Station, made waves in 2003 when he presented DNA evidence suggesting that populations of whales in the North Atlantic were as much as 10 times higher than previously believed. A year and a half later, the findings are still reverberating in the marine science community.

In July, Palumbi was invited to meet with the 250-member science panel of the International Whaling Commission. The industry group pledged to suspend commercial whaling until populations reach at least half of historic levels. Scientists on the panel drafted a list of questions for further study.

If validated, Palumbi's findings would support delaying the return of commercial whaling by decades. If not, some whale populations are edging toward levels where commercial boats could soon resume the hunt.

Phillip Clapham, a member of the U.S. scientific delegation to the International Whaling Commission and director of the federal large whale biology program in Seattle, said he is "very, very, very familiar" with the publication by Palumbi and then-graduate student Joe Roman in the journal Science.

"It's been a hugely controversial paper," he said.

Palumbi and Roman looked at blubber samples from hundreds of North Atlantic whales and analyzed the DNA. The theory is that if the whales have similar genes, they must be closely related, members of a small family. If their genes are very different, however, they are the few survivors of a once-teeming whale population.

It's a relatively simple idea, but interpreting the results means putting numbers to phenomena not fully understood. One unknown is how many generations of whales have occurred over the species' history.

Scientists estimate 12 to 25 years per generation, depending on the species of whale.

Another, more mysterious process is how fast the gene changes.

"I think there might be a serious issue with the mutation rate," said Per Palsboll, a population geneticist at the University of California at Berkeley, who also works on whales.

The genetic detectives also had to decide what constitutes a single whale population. Though humpback whales in the northern and southern hemispheres generally don't mix, long migrations could introduce new genes.

The researchers took all this into account and came up with an estimate of 360,000 fin and 265,000 minke whales in the North Atlantic before whaling, and 240,000 humpback whales -- more than 10 times the number previously believed.

But some scientists are skeptical.

"I don't agree with the method," Palsboll commented. "There are too many unknowns that you have to assume, and so your estimates of the population size are prone to too much uncertainty."

Clapham argues that even if accurate, the estimates are not tied to any point in time. Whales have lived through many ice ages, and likely had natural die-offs.

"(This population estimate) is the average over many, many thousands of years, and possibly longer than that," Clapham said. "What it is not is an estimate of how many whales there were prior to when humans started whaling."
 

Using whaling ships' logbooks

The other way to estimate historic whale populations is to look through whaling ships' logbooks. Using whaling ship records dating to the mid-1700s, scientists estimated 20,000 humpbacks originally in the North Atlantic, about twice today's numbers.

Tim Smith, a biologist at the Northeast Fisheries Science Center, and until last year the head of the U.S. science delegation to the International Whaling Commission, responded to Palumbi's findings by reviewing his own work on historic records.

The logbooks have many problems of their own. For example, the scientists have to estimate how many of the harpooned whales were pregnant females, and how many animals were struck and escaped, only to later die from their wounds. They also have to estimate how many whaling boats left no records or were illegal hunters.

In reviewing the findings, Smith took each uncertain value and chose the number that would give the most animals killed, he said. He got only twice the initial estimate.

"We have completed the historical review without being able to find any evidence of the high catches that Joe Roman and Palumbi's work imply," Smith said last week. "The difference between the two methods, the genetics and the historical logbooks, hasn't gotten smaller."

On his end, Palumbi's lab is working on five recommendations from the International Whaling Commission's science panel, most of which require more investigation into the genetic methods.

Meanwhile, Palumbi presented new research in February on Antarctic minke whales that live in the frigid Southern Ocean. They're being considered as a possible target to resume commercial whaling, because the current minke population of 760,000 is, some claim, unnaturally high.

Japanese members of the Whaling Commission argue that minkes are filling the habitat niche of blue whales. Palumbi's unpublished results suggest, once again, that minke whales are naturally far more abundant than previously thought. He said looking at two genetic markers, instead of one, makes the results more robust and corroborates the earlier findings.

However, Palsboll says the two genes are linked and would be expected to give a similar result.

"It's like looking at the color on one side of a car, and it's red, and then you take the color on the other side, and it's also red," Palsboll said of the result. "I mean, it's not so surprising."
 

A sea of whales?

Some scientists are skeptical that the world's oceans ever could have held hundreds of thousands of whales.

"The idea that there were a quarter-million humpback whales in the Atlantic Ocean at any time in history is, frankly, inconceivable," Clapham says. "The system simply couldn't support that number." If evenly distributed over the North Atlantic, the genetic results imply there were once 25,000 humpback whales and 39,000 fin whales living in the Gulf of Maine, he said.

Other marine experts argue that conditions have changed and even if today's oceans might not support so many animals, ancient seas may have done so.

"Anybody who looks at productivity today, not taking into account the exceptional productivity that existed in the past, they'd say 'Oh, it's impossible,'" said Jeremy Jackson, a marine biologist at Scripps Institution of Oceanography in La Jolla, who has studied the cumulative impact of fishing on the world's oceans. "Those kinds of arguments are deeply and fundamentally flawed."

Estimates of marine populations can be further complicated by natural fluctuations. The thousands of gray whales that swam by Carmel this winter on their southward migration route, for example, have recently been numbered at 17,000, said John Calambokidis, a whale biologist at Cascadia Research in Olympia, Wash.

After hunting ceased in 1986, gray whale numbers began to rise. When populations surpassed the logbook estimates of 12,000 by more than two-thirds in the mid-1990s, Calambokidis said, he questioned the logbook calculations.

But a major die-off from what appear to be natural causes five years ago brought the population back down. "And all of a sudden that data from whaling is looking not so far off," Calambokidis said.

Few people question the need to protect whales. The International Whaling Commission enacted a moratorium on whaling in 1986, responding to widespread collapses. Norway has continued commercial whaling and Japan uses a regulatory loophole allowing some scientific collection, Clapham said.

Palumbi's earlier sleuthing looked at the DNA of whale meat on sale at Tokyo markets and discovered that some was illegally taken from endangered populations.

The International Whaling Commission meets every year to discuss when hunting can safely resume. Its decision will depend, in part, on this question of historic populations.

Palsboll is trying to determine natural mutation rates in whale genes. He said he expects to have results in about five years.

Graduate student Liz Alter, in Palumbi's lab, is now looking at 10 different genes in Pacific gray whales, and hopes to have results within a year. Palumbi said they will not discuss the findings until the work is finished.

Despite the differences of opinion with logbook researchers, Palumbi said discussions over the past year have been amiable and productive.

"I think we agree that (genetic data and logbooks) are both important," Palumbi said. "The fact that they're so far apart is mysterious, and disturbing."