Skipjack tuna addition, skipjack's livers were tested globally for tributyltin contamination. TBT is an organotin compound introduced into marine ecosystems through antifouling paint used on ship hulls, and has been determined to be very toxic. About 90% of skipjack tested positive for contamination, especially in Southeast Asia, where regulations of TBT use are less rigorous than in Europe or the US. Skipjack tuna is used extensively in Japanese cuisine, where it is known as . Besides being eaten seared () and raw in sushi and sashimi, it is also smoked and dried to make katsuobushi, the central ingredient in dashi (a common
USS Skipjack (SS-184) coast of Timor which she reconnoitered and photographed. She also severely damaged an enemy oiler. The submarine returned to Fremantle for refit on 4 September. "Skipjack"’s fifth war patrol was conducted off Timor Island, Amboina, and Halmahera. On 14 October, while patrolling south of the Palau Islands, the submarine torpedoed and sank the 6,781-ton cargo ship, "Shunko Maru" (). Following a depth charge attack by a Japanese destroyer, the submarine returned to Pearl Harbor on 26 November. "Skipjack"’s sixth, seventh, and eighth war patrols were unproductive. But, during her ninth, conducted in the Caroline Islands and Mariana Islands areas, she