Japan, angered by world whaling ban, gets ready to defy it

With its back to the wall, a shocked and outraged Japan is considering how to defy a global ban on whaling after 1985.

The decision to end commerical whaling taken by the International Whaling Commission (IWC) in Brighton, England, last week was immediately condemned in Tokyo by government and industry.

A final decision on the course of action to be taken will be determined when the Japanese delegation returns from England this week. But Akira Matsuura, director general of the government's fishery agency, indicated that consideration would be given to ignoring the ban and withdrawing from the IWC.

''Japan will continue to make utmost efforts to continue commercial whaling, '' he declared.

The most likely immediate step will be for Japan to file a protest against the IWC vote within 90 days, as allowed under its regulations. Government sources said diplomatic pressure would also be applied on nay-voting IWC members , particularly the United States, which is seen here as leading the ban movement.

In the past two weeks, for example, the Japanese national news agency Kyodo received some 40,000 identical printed postcards from individual Americans pleading for Japan to ''stop killing whales.'' All the cards were handed over to the Foreign Ministry.

The Japanese whaling industry says the IWC ban will mean the end of a 1,000 -year history, plus the loss of employment for 1,300 workers directly engaged in catching and another 50,000 in related processing and distribution industries.

But this is a far cry from the 1960s. Then the Japanese caught some 20,000 whales a year, operating 10 large mother ship fleets in the northern Pacific and Antarctic and providing employment for about 1 million people. This has shrunk to one factory ship and four catching boats.

The Japan Whaling Association disparages suggestions that after a few years, when whale stocks have been replenished, they might be able to resume operations.

''Once we stop that would be the end of it,'' said a spokesman. ''It would be extremely difficult to start up again from scratch. That is why we have to ignore the ban.''

Both government and industry released statements attacking what they called the emotionalism and lack of scientific basis behind the IWC decision. Mr. Matsuura told reporters the IWC had contradicted its own purpose, having been set up in 1946 to promote commercial whaling while preserving whale resources. Japan, he added, had scrupulously observed this.

There is anger in Japan that the IWC in recent years has become packed with nonwhaling nations, as well as former whaling powers like the United States and Britain, accused of staying on merely to boost the antiwhaling vote.

Observers said the IWC had no legal powers to stop Japan - which currently accounts for 39 percent of the annual world whale catch - if it does decide to defy the ban.

But there are other considerations that could bring the Japanese into line. Government sources said there was a strong possibility the United States would retaliate by banning Japanese fishing boats from its 200-mile exclusive offshore zone.