Commercial whale hunting is now banned because stocks were sharply reduced in more than a century of hunting. But some countries, including Iceland and Japan, want to resume the hunts.
If stocks were really much larger in the past, new hunts could be delayed by the International Whaling Commission until the whale population builds closer to original levels. The commission says hunting should not be allowed until the population reaches at least 54 percent of the ocean's carrying capacity for the mammals.
Stephen R. Palumbi of Stanford University and Joe Roman of Harvard University used DNA analysis to estimate historical whale populations in the North Atlantic. They concluded that because of wide variation in whale DNA, stocks in the past were much larger than had been thought.
Using the totals from the new DNA study would require the moratorium on fin and humpback whales, at least, to be continued for 30 to 100 years, Palumbi said.
"We dare not base our whole approach to the natural world on phantom knowledge of what the past was like - we need to know what the past was," Palumbi said.
But their findings were questioned by researchers in the United States - which has voted against allowing whaling to resume - and in Iceland.
Current North Atlantic estimates are 10,000 humpback, 56,000 fin and 149,000 minke whales.
Previous estimates for the pre-hunting whale populations in the North Atlantic, based on hunting counts and reports from mariners, were 20,000 humpbacks and 30,000 to 50,000 fin whales, the researchers said. They said historical estimates for minke are harder to come by, but noted the commission uses a figure of about 100,000.
In their paper, published in Friday's issue of the journal Science, Roman and Palumbi conclude that the pre-hunting stocks totaled 240,000 humpback, 360,000 fin and 265,000 minke whales.
Both said they were surprised at how much higher their findings were than traditional numbers.
So were other whale experts.
Tim Smith, fisheries biologist at the National Oceanic and Atmospheric Administration's Northeast Fishery Science Center in Woods Hole, Mass., said he thinks the research paper is premature.
Smith said the new numbers are so much higher that the difference needs to be explained.
Roman and Palumbi "say the catch history must be faulty. My evaluation is that those historical catches, although there are uncertainties, can't be off as far as those numbers imply," Smith said.
Johann Sigurjonsson, director general of the Marine Research Institute in Reykjavik, Iceland, said it is "impossible" that so many fin and humpback whales lived in the North Atlantic prior to hunting.
"There is no way that whaling activities in the 19th and 20th centuries removed sufficient number of whales that could give rise to such high pre-exploitation stock sizes as indicated by the current genetic study," Sigurjonsson said.
He said Roman and Palumbi assume that whale fertility and age at maturity are constant, while these are actually variable, which could affect how much their DNA varies.
Thorvaldur Gunnlaugsson, a whale researcher at the institute, said other studies of mitochondrial DNA from whales have been inconclusive, noting there were variations between beluga whales at most locations.
He added that there are several documented instances of hybrids of blue and fin whales which appeared healthy and reproductive, "so genetic drift between these species and possibly minke, sei and bryde whales is not excluded. Certainly genetic drift between
the different forms of minke whales would be more likely."
Iceland has sought permission to hunt whales, as has Japan in the Pacific. Norway has ignored the ban since 1993. Japan does hunt whales for scientific purposes and Iceland has said it may begin doing the same. The pro-whaling countries have been backed by some Caribbean and African countries.
At the commission's meeting in Germany last month, the United States joined with other anti-whaling countries to defeat a Japanese proposal to resume commercial whaling.
By Randolph E. Schmid