This is an interesting one. Normally I seek out controversy, but here I am going to take some delight in pooh-poohing a pro-whaling claim that minke whales are super-abundant in the Antarctic and should be managed (or hunted) accordingly. Of course, most cetacean scientists actually believe whale populations are currently at a mere fraction of their pre-hunting levels. I personally am not ardently anti-whaling, and I have actually argued why the resumption of whaling might not be such a terrible thing, but these management decision should be based on good science.
There is theory known as the ‘krill surplus hypothesis’, which is based on claims that the removal of more than two million baleen whales from the Southern Ocean in the 20th century meant more krill were available to minkes, boosting their populations (known as competitive release). As can be expected, the pro-whaling bloc have pushed this idea as a justification for continued hunting of minkes, but a new study may have just ruined their argument.
The study, led by Kristin Ruegg of Stanford University, took a genetic approach (which is fast becoming the sexy science-of-choice in conservation) and used DNA evidence to estimate historical minke whale population numbers, and compare this to today’s estimates. Large populations tend to have greater genetic variation than small ones (which have more inbreeding), so the amount of genetic diversity within a population shed light on its historical size. For Antarctic minkes, this long-term population size is roughly 670,000 and is well in excess of more recent population estimates. It would seem, therefore, that there has been no such modern boom in minke numbers.
This might be because krill have always been abundant enough to satiate all baleen predators, or that minke whales differ to other great whales in where and when they feed. Either way, it would seem they have not experienced any competitive release, and there is no evidence to suggest they should be managed as if they have.
Ruegg, K., et al. 2010. Are Antarctic minke whales unusually abundant because of 20th century whaling? Molecular Ecology 19(2): 281-291.
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17/02/2010 Just as a follow on from this, another genetics-based studyhas shown that the northern right whale, which numbers in the low hundreds and is thought to have been driven to the brink by ye olde whale hunters in past centuries (the Basques mainly), has in fact probably always had natually a low(ish) abundance. The population has crashed from thousands to a few hundred, but not necessarily because of hunting. Read more on the BBC.
