Scientists are warning that a new form of unregulated whaling has emerged along the coastlines of Japan and South Korea, where the commercial sale of whales killed as fisheries "bycatch" is threatening coastal stocks of minke whales and other protected species.

Scott Baker, associate director of the Marine Mammal Institute at Oregon State University, says DNA analysis of whale-meat products sold in Japanese markets suggests that the number of whales actually killed through this "bycatch whaling" may be equal to that killed through Japan's scientific whaling program - about 150 annually from each source. The findings were presented their findings at the recent scientific meeting of the International Whaling Commission (IWC) in Portugal. Their study found that nearly 46 percent of the minke whale products they examined in Japanese markets originated from a coastal population, which has distinct genetic characteristics, and is protected by international agreements.

As many as 150 whales came from the coastal population through commercial bycatch whaling, and another 150 were taken from an open ocean population through Japan's scientific whaling. In some past years, Japan only reported about 19 minke whales killed through bycatch, though that number has increased recently as new regulations governing commercial bycatch have been adopted.

Whales are occasionally killed in entanglements with fishing nets and the deaths of large whales are reported by most member nations of the IWC. Japan and South Korea are the only countries that allow the commercial sale of products killed as "incidental bycatch." The wholesale price of an adult minke whale can reach as high as $100,000. In January 2008, Korean police launched an investigation into organised illegal whaling in the port town of Ulsan, reportedly seizing 50 tons of minke whale meat.

In Japan, whale-meat products enter into the commercial supply chain that supports the nationwide distribution of whale and dolphin products for human consumption, including products from scientific whaling. However, Baker and his colleagues have developed genetic methods for identifying the species of whale-meat products and determining how many individual whales may actually have been killed. Other protected species of large whales detected in market surveys include humpbacks whales, fin whales, Bryde's whales and critically endangered western gray whales.

The entanglement and death of western or Asian gray whales is of particular concern given the extremely small size of this endangered populations, which is estimated at only 100 individuals.