The debate over whether or not commercial whaling should resume turns in large measure on the extent to which whale stocks have recovered. Japan, Iceland and other countries argue that the number of whales has recovered enough to resume whaling, while many other countries argue that whale stocks still are not large enough to warrant a resumption of commercial whaling.
In the midst of that, two American researchers used DNA analysis of whales to argue that North Atlantic whales have been drastically undercounted historically. The researchers looked at the genetic variation among hundreds of specimens of whales and from there estimated what the whale population would have had to have been to support the level of genetic variation they saw.
Here’s a table showing the International Whaling Commission’s estimates of the pre-hunting stocks of several whale species compared to new estimates put forth by Stanford’s Stephen Palumbi and Harvard’s Joe Roman,
|
Species
|
IWC Estimate
|
Palumbi/Roman Estimate
|
| Fin | 40,000 | 360,000 |
| Humpbacks | 20,000 | 240,000 |
| Minke | 130,000 | 265,000 |
The researchers recognize that their claims could have an enormous impact on the decision of whether/when to resume whaling. Palumbi told The Globe and Mail,
Humpback whales, for example, were thought to have numbered about 20,000 in the North Atlantic, and we’re up to about 10,000 now, so at that rate, the IWC could allow countries to start killing humpbacks within the next decade. But if the historic population was really 240,000, as the genetics suggests, then we wouldn’t be able to start whaling for another 70 to 100 years.
Not surprisingly, these numbers came under quite a bit of criticism, the main one being that it seems difficult to account for the extraordinarily high level of killing of whales that would be required if their numbers were actually two to 10 times higher than previously believed (not to mention exactly what apparently millions of whales worldwide were eating that remained in abundance).
Whale biologist Robert Brownell pointed out that one possibility in reconciling the population based on genetic variation with whaling logs and other estimates of actual whales killed is that both numbers may in fact be correct. As Palumbi himself conceded, the technique he and Roman used is not able to estimate what the population of whales was before human hunting began, but rather what the whale population likely was tens of thousands of years ago. As Brownell told The Mercury News, “The main issue is that these estimates may be true, but we don’t know what time period they actually cover.”
As Brownell pointed out, there have been numerous climate and other changes in the last 10,000 years or so that may have drastically reduced whale populations long before human beings began intensively hunting them.
Palumbi, however, says that the technique should be to look at whales and give reliable estimates of their population just 1,000 years ago which would be useful to compare the IWC and other estimates with for accuracy.
Source:
New study revises estimate of early whale population. Glennda Chui, The Mercury News, July 29, 2003.
Gene Study Undermines Whaling Plans. Peter Lavelle, ABC Science Online, July 25, 2003.
Whales once numbered in millions. Oliver Moore, Globe and Mail, July 24, 2003.
Whale count wrong, DNA study reveals. Tim Radford, The Guardian (UK), July 25, 2003.