Forty-one legislators asked Gov. George Deukmejian to try to persuade Japan's prime minister to call off a whale hunt in the Antarctic Ocean. Deukmejian is scheduled to confer with Prime Minister Norboru Takeshita about economic issues today in San Francisco. "Despite a treaty with the United States to cease commercial whaling by the end of 1987 and the International Whaling Commission moratorium on all commercial whaling, a Japanese ship is sitting at the Antarctic, poised and ready to begin whaling as soon as the prime minister completes his North American trip," the lawmakers of both major parties said in a letter. They said Japan's claim that the pending hunt is for purely scientific purposes "is a poorly disguised attempt to circumvent the intent of the moratorium and treaty."