Of the 679 whales Japan reported killing during the hunt of 2008/2009, 304 were female. 192 of them were pregnant and four were lactating.

“The four lactating females would each have had a calf that would have starved to death,” said Michael Kennedy, director of the Humane Society International Australia.

The details of Japan’s impact on female whales was contained in what is known as a “Cruise Report”, secretly sent to the IWC’s* scientific committee before the IWC meeting in Portugal this week.

Japan claims that its whaling is legal, scientific research, but many opponents have spoken out against what they see as an unnecessary slaughtering of animals under the guise of science.

“They report they measure the length and weight of the foetus, they measure their eyes and take skin samples from the foetus for what they call genetic studies,” said Kennedy. “It is gruesome, useless information which, if it was even needed, could be found without dismembering a foetus.”

Australian Environment Minister Peter Garrett, who is attending the IWC meeting in Portugal, said Japan had killed more than 13,000 whales in the name of science IWC banned commercial whaling in 1986.

* International Whaling Commission