"Pollack" got underway from Pearl Harbor on 28 February 1944 and battled heavy seas as she entered the assigned area of her ninth war patrol off Nanpō Islands 18 March. Two days later she made a night surface attack and watched two torpedo hits blow the 1,327-ton patrol boat "Hakuyo Maru" to pieces. On 25 March she sank the 300-ton "No.13-class" "Submarine Chaser No. 54", and damaged two freighters. On 3 April she sank passenger-cargo ship "Tosei Maru". She returned to Midway on 11 April.