 During fiscal year 1925 (1 July 1924–30 June 1925), "Halcyon" steamed .Although she devoted the winter of 1924–1925 to fish-culture work in support of the BOF fish hatchery at Gloucester, Massachusetts, she spent much of the rest of the fiscal year investigating fisheries in the Gulf of Maine, operating from Nantucket Shoals to Mount Desert, Maine.Most of her work during the fiscal year involved tagging cod, haddock, and pollack to gain data on their migrations, and her crew and embarked scientists tagged 16,000 fish during the fiscal year.