By Richard Black
Environment correspondent, BBC News website, Japan
"Japan's scientific whaling is just commercial whaling in disguise."
It is probably the criticism most often levelled at Japan's whaling programme, one of only three in the world currently to target the "great whales".
But is it fair criticism? I had long wanted to look at Japan's scientific whaling in a bit more depth. And for the BBC's One Planet series, I got the chance.
In the Institute of Cetacean Research (ICR), housed in an anonymous building near the docks in downtown Tokyo, the organisation's director-general Hiroshi Hatanaka explains the purpose of the Antarctic and North Pacific programmes which he supervises.
"The mission of this institute is to conduct research and surveys on cetacean resources," he tells me; "that is, to conduct biological research and surveys on cetacean resource abundance and to make good use of it for the sustainable use and rational management of cetacean resources.
"The (International Whaling Commission or IWC) moratorium was introduced because at that time there was not enough biological data to secure that commercial whaling was free from danger (to cetacean resources)."
The ICR and the Japanese government's Fisheries Agency believe that if enough of the right sort of data can be collected, they can go back to the IWC and prove scientifically that some whale stocks are robust enough to allow a degree of sustainable commercial hunting.
Key to this is the "stock structure"; in other words, which whales belong to which populations, and how much those populations mix.
DNA research has, for example, shown there are two distinct populations of Antarctic minke whales in the regions surveyed by Japanese ships. This kind of information would be vital in deciding commercial quotas.
The ICR also gathers information on the age distribution within each population (which relates closely to the natural rate of mortality), blubber thickness (an indication of health and food supply), and diet.
"In practice, we have to cut open the whales' stomachs to be able to take out all their contents and transfer them into buckets," relates Tsutomu Tamura, a whale feeding ecologist.
Naohisa Kanda's laboratory analyses whales' DNA
"Once in the buckets we record their weight. Afterwards, we bring them back to the laboratory where we examine in detail more specific items like the kinds of species present, their size, their weight, and thereby collect additional data."
Rummaging in a stereotypically untidy scientist's office, Dr Tamura unearths bottles of otoliths taken from whales' stomachs. These hard tiny structures come from the ears of fish that the whales have eaten.
A larger bottle holds krill, the whales' staple diet in the Antarctic.
The ICR also believes that killing whales is the only way to determine a whale's age reliably. This is done by examining earplugs, hard waxy structures which accumulate annual growth rings, like those of a tree, as they grow in the whale's ear.
A scientific whaling programme does not only consist of killing animals.
Japan's Antarctic fleet is led by a sighting boat carrying international observers. They scan the oceans visually, recording the abundance of various whale species and, where possible, identifying individuals visually.
Humpbacks, for example, often have individualised colour patterns on their bodies and nicks in their tail-flukes.
The fleet sails in a pattern designed to make a representative survey of the ocean. Commercial hunters, by contrast, would just head for the biggest concentration of whales they could find.
Scientists also take biopsy samples from species, such as blue whales and humpbacks, which are not hunted, firing a dart into the whale's body and pulling back a sample of tissue.
This is where part of the controversy lies. Some scientists believe that biopsies, combined with sighting data and collection of whales' faeces, could provide the same information that Japan obtains without killing the creatures.
A project called Years of the North Atlantic Humpback (Yonah), for example, used visual identification and repeated biopsies to map migration patterns and estimate abundance.
Biopsies can, in principle, provide age information, by examining telomeres (structures on the end of chromosomes that decay with age), on reproductive status (through hormone analysis) and on diet (by analysis of stable isotopes, chemical traces of prey).
Faeces can also provide genetic material and dietary information.
But they are hard to collect, for obvious reasons. And Tsutomu Tamura does not believe non-lethal methods of assessing diet provide anything like the same accuracy of information.
"Biopsy sampling... can tell you just about what type of food, whether fish or krill, but not what kind of fish," he says.
"Collecting faeces... doesn't tell you how much the whale has eaten, it just doesn't provide data to make a quantitative estimation. That is why we need to do stomach contents, and that implies using the lethal method."
William Evans, a former US Whaling Commissioner and cetacean scientist who is a strong advocate of non-lethal methods, acknowledges that some lethal research might be necessary from a strictly scientific standpoint.
"There are certain kinds of data that we can get remotely through observation and tagging and other kinds of non-invasive methodology," he tells me from Notre Dame University in the US where he currently edits an ecology journal.
"But... you have really got to use more invasive techniques in order to get certain answers that you're looking for."
Another factor behind the lethal component of Japan's research is money. Sending ships to the Antarctic for months at a time is expensive, costing thousands of dollars per day; and sales of meat from the whaling programme, some taking place in the vast Tsukiji fish market just around the corner from ICR, pay for most, though not all, of the research.
So how valuable is Japan's Antarctic research programme to the community of international cetacean researchers?
"The Japanese input into cetacean research in Antarctica is significant, and I would say crucial for the (IWC) scientific committee," observes Arne Bjorge from the Institute of Marine Research in Oslo, scientific committee chair.
In November, the IWC held a meeting to review the first 18 years of Japan's Antarctic scientific whaling programme.
The review is being finalised in Anchorage, Alaska, ahead of this year's IWC meeting. But of the parts completed so far, what did the scientific committee decide?
"To make it very short, the review panel was very pleased with the data (Japan has) collected and provided from the programme," says Dr Bjorge.
"There was some advice on how these data could be further analysed, or better analysed, but there was general consensus about the high quality and the usefulness of the data."
Another western complaint is that Japan's scientific whaling is illegal.
But the International Convention for the Regulation of Whaling (ICRW), which is the IWC's basis, states that "any contracting government may grant to any of its nationals a special permit authorising that national to kill, take and treat whales for purposes of scientific research... whales taken under these special permits shall so far as practicable be processed..."
Legal panels periodically convened by conservation groups have argued that Japan's current programmes in the Antarctic and North Pacific fall outside the original scope and purpose of scientific whaling, or that they contravene other marine treaties.
But such panels have all the power of governments in exile.
Whale meat in the Tsukiji market helps pay for the expeditions
So to come back to the original accusation; is scientific whaling just commercial whaling in disguise? To put it another way; are commercial forces driving the research programme?
Certainly the whaling industry has some influence, particularly with politicians who, like Prime Minister Shinzo Abe, come from whaling regions.
But as one Japanese MP told me: "If the head of Toyota asks us to do something, we listen; whalers are really a minor force by comparison."
Perhaps the most important driving force is exactly what the ICR says it is; to "resolve the scientific uncertainties and pave the way for a resumption of sustainable whaling".
Whether it is justified, I think, depends on your point of view. If you believe that no whales should be killed as a matter of principle, clearly scientific hunting makes no sense; it is just as unethical as commercial whaling.
But if you believe that whales are no different from other wild animals, that there is no compelling ethical reason why they cannot can be hunted and eaten like boars and deer and salamanders, then Japan's logic begins to emerge.
Officially, the 1982 IWC moratorium was not a complete halt to whaling but a pause; and Japan hopes the data it gathers will eventually convince the IWC on scientific grounds that commercial whaling can be licensed again.