The SS-177 U.S.S. Pickerel submarine was commissioned in 1937. Following Pearl Harbor, she deployed to the Cam Ranh Bay area under the command of Lieutenant-Commander Barton Bacon, Jr. Her first patrol brought no results, the five torpedoes she fired either missed or failed to explode. (At that stage of the war, both were distinct possibilities.)
Returning to Manila, Pickerel quickly departed on her second war patrol, sinking the 2,929-ton armed freighter Kanko Maru in a submerged night attack on 10 January 1942.
Her third and fourth patrols produced neither worthwhile targets nor hits. Sent to Pearl Harbor for refit, she patrolled in the Mariannas en route, damaging a 4,800-ton freighter. After reaching Pearl Harbor on 26 August, Pickerel was ordered back to Mare Island Navy Yard for refit.
At Mare Island, she received a number of the standard wartime modifications, including cutting down the large pre-war conning tower to reduce her silhouette and provide platforms for 20mm anti-aircraft guns on the fore and after part of the conning tower. She also had external torpedo tubes added to her superstructure, increasing her forward battery—for the first salvo, at least—to six.
Her sixth war patrol commenced on 22 January 1943, with Lieutenant-Commander Augustus Alston, Jr. having assumed command. Patrolling in the Kuriles, Pickerel sank the 1,990-ton auxiliary Tateyama Maru on 15 February, and destroyed two sampans by gunfire on the 20th, returning to Pearl Harbor on 3 March.
Pickerel departed on her seventh and final war patrol on 18 March, topping up fuel at Midway before continuing on to patrol in Empire waters. Japanese records show a bombing attack on a submarine off Honshu on 3 April, followed up by depth charge attacks from a minelayer and an auxiliary sub chaser. Pickerel was the only American submarine in the area at the time.