Peter Aldhous, New Scientist 30 Sep 09;
A high proportion of the whale meat on sale in Japan comes from a population of north Pacific minke whales that some fear is under serious threat.
The finding, from a forensic DNA study of meat bought on Japanese markets, suggests that either Japan's scientific whaling programme is taking more animals from this population than previously estimated, or accidental "by-catch" of the whales in fishing nets is larger than officially reported.
Vimoksalehi Lukoschek of the University of California, Irvine, and Scott Baker of Oregon State University in Newport, along with their colleagues, bought samples of whale meat in Japan and used DNA analysis to determine in each case not only the species of whale, but also which population it came from.
They found that a disturbingly high proportion came from a population of north Pacific minke whale that was selected for protection by the International Whaling Commission (IWC) in the 1980s, before the wider moratorium on commercial whaling came into effect.
Scientific whaling
Much of the whale meat on the Japanese market comes from a different species of minke whale, caught in the Antarctic by the nation's controversial scientific whaling programme. But a smaller scientific hunt also targets north Pacific minkes, killing 169 of the animals in 2008. Most of those killed are thought to come from a relatively abundant population to the east of Japan called the "O" stock. However, some are thought to come from the protected "J" stock, which mostly lives in the Sea of Japan.
To find out exactly where the whale meat on sale in Japan was caught, the researchers analysed 1200 samples of Japanese whale meat between 1997 and 2004. They found that 250 of the samples came from 201 north Pacific minke whales. An alarming 46 per cent of these appeared to be from the protected J stock.
"That would mean that either by-catch is higher, or more J stock is being caught in the scientific hunt," says Lukoschek. Both O and J stock whales can be caught in fishing nets as by-catch, in which case they can be sold for meat.
Hit from two sides
The numbers are worrying, says Baker, because the J stock is being hit from two sides. He has previously shown that this population is also being depleted by heavy by-catch from South Korean fishing.
Luis Pastene, director of the research division at the Institute of Cetacean Research in Tokyo, which runs Japan's scientific whaling programme, rejects the findings, calling studies based on meat purchased in markets "not reliable".
Pastene adds that the status of the J stock is currently being assessed by the IWC's scientific committee . "It is important to avoid speculations on its status in the meantime," he says.
But the scientific committee's assessment could take several years to complete, and some committee members claim that Japan is delaying the process by failing to provide information from its own whale DNA registry. "They say that Baker's data are wrong, but they don't provide us with anything solid to critique the analysis," says Phil Clapham of the US National Oceanic and Atmospheric Administration's National Marine Mammal Laboratory in Seattle.
Journal reference: Animal Conservation, vol 12, p 385
