Japanese whaling vessels set sail yesterday on a six-month expedition to hunt up to 400 minke whales in the Antarctic. A 1986 ban on commercial whale hunting by the International Whaling Commission does not apply, because Japan claims the goal of the expedition is to gather data on the feeding habits, migration patterns, and lifecycle of the whales. Opponents are calling for the use of non-lethal research methods and say the expedition is a commercial hunt in disguise. Whale meat from the expedition will be sold in Japanese restaurants, where it is a delicacy. Japanese fishery officials estimate that there are 760,000 minke whales in the Antarctic and say whaling does not threaten the species, but opponents question those numbers and the IWC plans to conduct its own survey.