In 1635, under pressure from the Church of England for his nonconformity, the Rev. Richard Mather decided it was time to leave England with his wife and sons and start a new life in New England.

The sea crossing took three weeks. At Cape Cod, Mather wrote in his journal that he was already quite used to seeing “multitudes of great whales, which was now grown ordinary and usual to behold . . . spewing up water in the air like the smoke of chimneys and making the sea about them white and hoary.”

At the time that Mather traveled to Massachusetts, whales were abundant. Their numbers steadily decreased in the centuries that followed and plummeted in the 20th century. By the 1970s some species, far from making the sea hoary, seemed to have vanished altogether.

Supermarket shelves in Japan were once crowded with blubber, whale bacon and the deep red, almost black meat. Now, scientists estimate that the numbers of southern blue and humpback whales are just a fraction of their previous levels.

In contrast, meetings of the International Whaling Commission are plenty frothy and hoary.

Last month in Berlin there was a particularly acrimonious meeting that ended with the decision to create a conservation committee for whales. Japan’s chief delegate, Minoru Morimoto, threatened to quit the commission.

It is not always possible to remain objective in the whale-hunting debate, and data is claimed or disputed by both sides.

For example, as The Japan Times reported in an editorial in June: “Debates between prowhaling and antiwhaling members appear to be going nowhere, as the ‘save-the-whale’ group rejects scientific findings that clearly show whale stocks increasing.”

There are all sorts of problems here, and the biggest is this: Whale stocks (of some species) might well be increasing, but does that mean there are populations big enough to sustain commercial exploitation of them?

The IWC itself states that “catches should not be allowed on stocks below 54 percent of the estimated carrying capacity.”

The carrying capacity is the number of whales (or any other animal) that a given area can support. But it’s hard to say what the carrying capacity of whales is, because they are hard to observe and because of the effect of hunting over the last 200 years.

But now a genetic study has indicated that North Atlantic whales were far more abundant before commercial hunting than previously thought.

Joe Roman, of the department of organismic and evolutionary biology at Harvard University, Mass., and Steve Palumbi, of the department of biological sciences at Stanford, Calif., used variations in mitochondrial DNA to estimate past population sizes.

They found that North Atlantic humpback, fin and minke whales had much higher genetic variations than previously thought, suggesting that the population size of all three species was far higher, too.

Historical records are based on whaling log books, which “may be incomplete, intentionally under-reported, or fail to consider whales which were struck and lost,” the scientists write.

By analyzing mitochondrial DNA, the scientists can gain an insight into the genetic diversity of whale species. Mitochondrial DNA is transmitted via the female line only, and Roman and Palumbi looked at mutations in it to construct a kind of “biological clock” that enables them to estimate the sizes of previous populations.

“Estimates for fin and humpback whales are far greater than those previously calculated for prewhaling populations and 6 to 20 times higher than the present population estimates,” write the pair.

“In light of our findings, current populations of humpback or fin whales are far from harvestable. Minke whales are closer to genetically defined population limits and hunting decisions regarding them must be based on other data.”

In an e-mail interview, Palumbi added: “The key implication of our numbers is that we have forgotten that there used to be vast numbers of whales, and we have gotten used to oceans where whales are very scarce. They do not need to be scarce, but will always be so if we harvest them at too small a population size.”

What about the charge that whales are depleting fish stocks?

“If the oceans were once home to millions of whales, then the current numbers are so far below this that there is probably little impact on fish stocks. I would ask for the firm quantitative evidence for fish depletion,” Palumbi said.

He concluded: “I have no problem with the idea of commercial whaling for food. I have a serious problem in basing the hunt of these long-lived animals on poor data and unconfirmed assumptions. Our genetic results suggest that prior assumptions about the historical number of whales were very wrong, and these discrepancies must be reconciled.”

The decision by the IWC last month was greeted with dismay by Japan, Norway and Iceland.

These nations claimed that conservation was outside the commission’s mandate. The Japan Times editorial tutted: “It is difficult to escape the impression that the IWC is becoming increasingly like an ‘international antiwhaling commission.’ “

Yet it is the job of the IWC to ensure sustainable hunting of whales.

If that can’t be done — and according to this week’s Science paper it seems that it can’t — then by maintaining the moratorium on hunting the IWC has simply done its job.

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