The government of Japan does not stop Japanese whaling for several reasons. First, there is no domestic constituency that can pressure the Government of Japan to end whaling. This is partly due to a weak Japanese environmental movement. Most Japanese see environmental problems in terms of air and water pollution and have little awareness of animal rights. They also equate harvesting whales to the cattle industry.
Second, the government of Japan is vitally concerned with protecting its rights to global resources, especially those of the oceans, from which Japan gets about 40% of its food. Without considerable international economic pressure to its economic interests, it will never change its whaling policies, even with the anti-whaling diplomacy of the U.S., Australia, and New Zealand through the IWC (International Whaling Commission).
Third, the Japanese whaling industry is a significant part of the politically powerful Japanese fishing industry. As I explained above, in terms of diet and environmental attitudes, the Japanese people do not support, or even understand anti-whaling sentiment, which, in any case, is not reported in the Japanese press. (I am just returned from eight days in Japan.)
When I first heard that some schools in Japan were trying to feed whale meat to Japanese school children, I thought surely not, but then I found the following 2005 article from BBC News about that very practice: http://news.bbc.co.uk/1/hi/world/asia-pacific/4106688.stm So, the campagn is unfortunately true. The article makes the point that whaling is not important to the average Japanese, thus there might be hope that they can be reached with the anti-whaling message.
If diplomatic pressure is not working; if the confrontational direct actions of Greenpeace and Sea Shepherd are not working; then boycotting Japanese products is probably the only hope. But, it would have to be so massive that it would enter the civic dialogue in Japanese society. Right now, this is not happening; and, powerful forces are at work to prevent the message from affecting the government of Japan and reaching the Japanese people. It will have to be a message sufficiently powerful to shake the table on which Japanese eat.