Although most of the vessels she sighted were neutral Spanish ships, the submarine sank an enemy trawler, a barge, and severely damaged a destroyer escort before she returned to Roseneath for refit on 12 February 1943.

Although no positive evidence of any sinkings was found, a two-square mile 2 sq mi (5.2 km2) oil slick confirmed the damage done by the submarine.

Shad then returned via Midway Atoll to Pearl Harbor, where she terminated her sixth patrol before sailing for the West Coast for overhaul at San Francisco.

After returning to Pearl Harbor on 11 May 1944, Shad underwent further repair work and training before departing on 12 August for her seventh war patrol, which she conducted in waters surrounding the Japanese home islands.

Although evidence of one hit was noticed, exact results were unknown due to a severe counterattack that forced the submarine to leave the area, giving the freighter a chance to escape.

On 19 September, Shad torpedoed and sank escort ship Ioshima, and as expected, was forced to endure another lengthy depth charging.

Shad spent her eighth war patrol as a unit of a coordinated attack group with Redfish and Thresher, in the area off the northeast coast of Formosa and in the East China Sea.

On her tenth war patrol, Shad operated as part of yet another coordinated attack group with Balao, Dragonet, and Spikefish, this time in the Yellow and East China Seas.

One torpedo hit forward on the freighter Chosan Maru, blowing her bow completely off, and the target settled quickly to the bottom.

The submarine continued in that duty until she was struck from the Navy List on 1 April 1960 and sold for scrap to Luria Brothers, Inc., of Kearney, New Jersey.