A quarter-century ban on commercial whaling — one of the world's most successful preservation agreements — could crumble altogether if conservationists can't persuade Japan to cut back on the tradition it champions.

Delegates to this week's meeting of the International Whaling Commission in Morocco will consider whether to allow limited commercial hunts if Tokyo stops pursuing whales in a southern sanctuary. Even adamant opponents are willing to sanction limited hunts on that condition, but it appears to be more than the Japanese are willing to concede.

"Japan holds the key, because Japan is the only country that is whaling in the Southern Ocean, the only country whaling in the sanctuary, the only country doing high-seas, long-distance whaling," said Susan Lieberman, director of international policy at the Pew Environment Group, which supports allowing some whaling.