[3][4] O'Malley became field superintendent in December 1913, in charge of all BOF fish-culture work on the United States West Coast.

[6] An experienced fish culturist and an advocate of fisheries science and related scientific research, O'Malley brought a deep understanding and appreciation of the BOF and its efforts to the commissioner's position, which he assumed on May 17, 1922.

[1][5][7] For the rest of his tenure as commissioner, O'Malley annually spent the entire fishing season in Alaska[7] to oversee personally the implementation of BOF regulations and policies authorized by the law.

[1] This played an important role in the rehabilitation of what had been badly depleted salmon runs and other fisheries in Alaskan waters and establishing their future sustainability.

[1] His last day of employment was August 31, 1934,[1] and he retired effective September 1, 1934,[7] due to medical disability after almost 37 years of service in the Fish Commission and BOF.

[1][4][9] The May 1, 1936, edition of the BOF's Fisheries Service Bulletin described O'Malley as a man known for "his kindly and gentle nature, his ready wit, his unswerving loyalty to his friends, and his resourcefulness in handling problems confronting him.

"[1] It added that "[h]is attainments in his chosen field, rising as he did from the lowest [position in the Fish Commission] to the highest [in the BOF], should be a constant inspiration to others.