sentences:  Assigned to the Atlantic Fleet, "Mallard" conducted minesweep duties in the 3rd Naval District through the next nine years.Transferred to submarine rescue operations following conversion at Boston Navy Yard June to December 1928, "Mallard" was redesignated ASR-4 on 12 September 1929.From January to March 1929 she joined submarine in experimental maneuvers off Key West, Florida.