04 February 2010

No reason to kill minke whales

Some think Antarctic minke whales (Balaenoptera bonaerensis) are more numerous than usual, that they compete for food with larger whales and they are preventing them from recover after decimation by industrial whaling. Therefore, culling of minke whales was proposed as a valid management solution to allow blue, sei, fin and humpback whales to increase in numbers.

A recent study published on Molecular Ecology confuted this theory. Based on analyses done on samples of minke whale meat purchased at Japanese markets, researchers proved that numbers B. bonaerensis have not increased unnaturally in the wake of industrial whaling. No way. Their numbers are close to historical ones.

Silvia Bonizzoni

Image: Four main species of baleen whale hunted in the Southern Ocean in the early 1900s (from Ruegg et al. 2010)

For more information:

Ruegg K., Anderson E., Baker C., Vant M., Jackson J., Palumbi S. 2010. Are Antarctic minke whales unusually abundant because of 20th century whaling? Molecular Ecology 19(2):281-291.
Abstract - Severe declines in megafauna worldwide illuminate the role of top predators in ecosystem structure. In the Antarctic, the Krill Surplus Hypothesis posits that the killing of more than 2 million large whales led to competitive release for smaller krill-eating species like the Antarctic minke whale. If true, the current size of the Antarctic minke whale population may be unusually high as an indirect result of whaling. Here, we estimate the long-term population size of the Antarctic minke whale prior to whaling by sequencing 11 nuclear genetic markers from 52 modern samples purchased in Japanese meat markets. We use coalescent simulations to explore the potential influence of population substructure and find that even though our samples are drawn from a limited geographic area, our estimate reflects ocean-wide genetic diversity. Using Bayesian estimates of the mutation rate and coalescent-based analyses of genetic diversity across loci, we calculate the long-term population size of the Antarctic minke whale to be 670 000 individuals (95% confidence interval: 374 000–1 150 000). Our estimate of long-term abundance is similar to, or greater than, contemporary abundance estimates, suggesting that managing Antarctic ecosystems under the assumption that Antarctic minke whales are unusually abundant is not warranted.

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