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 (SSN-585) an extended deployment in October and November, the submarine returned to Norfolk to prepare for major operations of that year which she completed on 25 February 1968. The remainder of 1968 was spent in local operations in the Norfolk area. On 9 April 1969, "Skipjack" commenced an overhaul in the Norfolk Naval Shipyard which was completed in the fall of 1970. After sea trials in December 1970, "Skipjack" returned to her regular duties. Highlights of 1971 were sound trials and weapons system tests at the Atlantic Fleet Range, Puerto Rico, from 25 January through 5 March and NATO exercise "Royal