The thermonuclear tests of Mike on Eniwetok Atoll in 1952 and particularly the Bravo test on bikini Atoll on 28 February 1954 sharply increased the radioactive fallout in the surrounding oceanic areas in . 1954. To measure this, the Japanese survey ship Shunkotsu-Maru during fay and June of 1954 made several traverses of the Pacific currents to determine the amounts of radioactivity present in sea water and marine life (Hines, 1962, p. 182; and Miyake et al, 1955). The technique of precipitation used by this Japanese expedition eliminated natural potassium-40 and also eliminated some fission products such as cesium and some of the ruthenium and niobium. Nevertheless, the maximum activity found in sea 7. water was about 91,000 disintegrations per minute and per liter on‘ 21 June 1954 at 450 kilometers west of Bikini. ‘ Over 1,000 disintegrations per minute aud pox liter wore fovnd oe far ae 2000 kilometers WNW of Bikini. The Japanese found this activity largely to be in solution, since it passed through a fine filter paper. Samples taken with depth showed the activity at some locations was present down to several hundred meters depth. BEST AVAILABLE Copy Less than a year later, the United States sent a survey ship, the U.S. Coast Guard cutter Taney, also to collect radioactivity samples (Harley, 1956; and Hines, 1962, p. 201). until 3 May 1955. The survey was from 7 March 1955 As with the Japanese survey, potassium andcesium were not precipitated in the samples counted, and the ruthenium, niobium, and promethium were only partly precipitated. \ Water activity at zero to 570 disintegrations per minute and per liter was far less than observed by the Japanese in the previous year. Plankton activity was 3 to 140 d/min-¢), while the highest activity for fish was 3.5 d/min+g for 19 3)