Over two decades, Japanese ships have butchered thousands of whales taken from the icy waters around the Antarctic in the name of research. Campaigners and politicians condemn the practice as unethical and unnecessary, and say Japan's "scientific" whaling programme is commercial whaling by another name.
Now, Japan's scientists claim their controversial whaling programme has produced a key finding. Measurements taken from more than 4,500 minke whales slaughtered since the late 1980s reveal the animals have lost significant amounts of blubber, and are getting thinner at a worrying speed. The team says its study offers the first evidence that global warming could be harming whales, because it restricts their food supplies. And they say the discovery could only have been made by killing the animals.
Crucially for the Japanese, the results have been published in a mainstream western scientific journal – a move that has dismayed campaigners, who say it could offer scientific whaling a veneer of respectability, and bolster Japan's efforts to hunt more whales.
They fear Japan could use the results to support efforts to hunt endangered humpback whales for the first time in 50 years. The study claims the recovering humpback population in the Southern Ocean could also be hurting the minkes because of "interference" between the two species as they compete for food.
Lars Walloe, a Norwegian whale expert at the University of Oslo, who helped the Japanese team analyse the data, and is listed as an author on the new study, said: "This is a big change in blubber and if it continues it could make it more difficult for the whales to survive. It indicates there have been some big changes in their ecosystem."
Whales rely on their thick layer of blubber for energy and as insulation against the cold water. The shift could already being making it more difficult for them to reproduce, Walloe said. "I don't think you could measure this by other [non lethal] means." Alternative methods to sample blubber, such as ultrasound and biopsy darts, have been developed. But Walloe said it was not practical to use them on the required scale with minke whales, which are also difficult to approach.
He said the Japanese findings, and their publication, had been unpopular among scientists from nations opposed to whaling, including Britain. Two journals refused to print the findings before they were accepted by Polar Biology, which published them online last month. Walloe, who says he does not support the current ban on commercial whaling, claimed that the journals that turned down the study did so for political, not scientific, reasons.
This is not the first time that the Japanese scientific whaling programme has published results, but these are the most high-profile findings so far. In 2005, Australian scientists analysed the 55 scientific papers produced by the programme and said only a handful were relevant and required the whales to have been killed. The others included descriptions of bizarre experiments to cross-fertilise whales with sheep and cows.
The new study analysed measurements taken from 4,689 adult whales killed by the Japanese whaling fleet between 1988 and 2005. It found that blubber thickness and overall fat weight had decreased by 9% over the period, which it called a 'substantial decline". Girth of the animals was down 4%. The study says: "This is the first time a long-term decline in energy storage in minke whales has been demonstrated."
It also demonstrates the brutality of whaling, which the paper describes as carried out using "explosive harpoons and a large calibre rifle in the event that death was not instantaneous". Several of the dead whales had to be excluded from the new analysis because their blubber was too badly damaged to be measured accurately.
Mark Simmonds, director of science at the Whale and Dolphin Conservation Society, said: "Lots of dead bodies will provide robust data, so if you kill lots of whales then you will be able to get some information. The question is whether the benefits outweigh the number of whales killed and how they were killed. Scientific whaling is not about science, and there is no pressing conservation need that requires it to be done."
He said the results should not have been published on ethical grounds. "Journals need to think very carefully about information that comes from this source. Different journals have different ethical standards." The editors of Polar Biology could not be reached for comment. British whale scientists were reluctant to discuss the research, which one described as "very worrying if true".
Walloe said the decline in blubber was down to shrinking numbers of Antarctic krill, a shrimp-like crustacean at the heart of the food chain. The amount of blubber lost is roughly equivalent to 36 fewer days of intensive summer feeding.
Krill numbers in the water around the rapidly-warming Antarctic peninsula have collapsed by about 80% since the 1970s. This is blamed on the loss of sea ice, which provide shelter and food for krill.
The study says the impact of global warming on the minke whales is unclear because no similar krill measurements have been made in that region of the Southern Ocean. But it claims that competition for krill from other predators such as the humpback must also be "considered as a likely explanation".
Science and slaughter
Japan's scientific whaling programme, known as JARPA, began in 1987 following the moratorium on commercial whaling. Japan says its research is aimed at overturning the ban, by providing evidence that stocks could be hunted in a sustainable way.
Critics say it is limited commercial whaling in disguise because the meat is sold for food, and that whales do not need to die to provide the required information on population numbers and structure. Until 2005, Japan killed up to 440 minke whales in the Southern Ocean each summer. Recently it has doubled that quota, and last year said it would hunt dozens of endangered fin and humpback whales for the first time in decades, until it backed down "temporarily" under intense political pressure.
Until now, the most high-profile claim from the programme was that whales should be killed to conserve fish stocks – an idea ridiculed by fisheries experts.