"Big Flo" and "Baby Flo", the inflatable whale balloons, flew above Boston yesterday in honor of Mayor Kevin White's proclaimed "Save the Whale Day 1979."

"Big Flo," 100 feet long, took off from City Hall Plaza at 8 a.m., and "Baby Flo" took off from Fanueil Hall at noon. The smaller of the two gaseous giants, a mere 40 feet long, migrated down Boylston St. from the Christian Science Center to Copley Sq.

"The whales are on a nation-wide tour to help promote a ten-year moratorium on whale killing at the next International Whaling Commission meeting," Deirdre Devine, a spokesman for Greenpeace, a Boston-based seal and whale conservation group, said yesterday.

The commission, which includes one U.S. delegate, will meet in London on July 9.

Steven G. Sawyer, one of several who flew the whales yesterday, said original plans called for a launching of the leviathans in Harvard Yard. but the crew was "too tired" to make the trek to Cambridge.

Sawyer added the flying whales are not affiliated with any one organization, adding, "They 'flo' between them all."