[2] In June 1917, the U.S. Navy purchased Calypso from her owner, A. L. Mason of Westfield, New Jersey,[2] for use as a section patrol boat during World War I.

Prior to Calypso's official transfer, the Bureau of Fisheries took possession of her at Quincy, Massachusetts, in July 1919 and renamed her USFS Merganser.

[2] In March 1921, the United States Forest Service vessel Hiawatha towed Merganser to Ketchikan, Territory of Alaska.

[2] After two months in Seattle, she was loaded aboard the Northwestern Fisheries Company ship St. Paul, which transported her to Chignik, Territory of Alaska, arriving there on 25 April 1922.

[2] Merganser finally took up her fishery patrol duties during the 1922 fishing season, and began her career of law enforcement protecting halibut, salmon, sea otter, and fur seal populations in the waters of the Territory of Alaska.

[2] Sent to search for her, the United States Coast Guard cutter USCGC Haida discovered her 10 days after she ran aground and pulled her free; Merganser was found to have suffered only minor damage.