OPERATION TROLL During May and June of 1954, the Japanese survey ship SHUNKOTSU-MARU made several traverses of Pacific currents to measure the amounts of radioactivity present in sea water and marine life. The Japanese scientists returned to Tokyo on July 7, 1954, and their results were published in "Papers in Meteorology and Geophysics," Miyake, Sugiura and Kameda, Vol. V, Nos. 3-4, 1955. These particular results were made available to Mr. Merril Eisenbud through the courtesy of Dr. Miyake at the Radiobiology Confererice held in Tokyo in November of 1954. Thus, the AEC staffs in the Division of Biology and Medicine and the Health and Safety Laboratory had a chance to study the original data before publication. The maximum sea water activity* found during the Japanese expedition was about 91,000 d/min/liter, 450 km west of Bikini on June 21, 1954. Over 1000 d/min/liter was found as far as 2000 km WNWof Bikini. According to the Japanese scientists, this activity was in solution, since it passed through a fine filter paper. In addition, samples taken in depth showed activity was present at some locations down several hundred meters. General consideration of the decay and dispersion of the radioactivity indicated to Mr. Eisenbud that it was possible that measurable activity from the nuclear tests at the Eniwetok Proving Grounds in the Spring of 1954 might still exist in the Pacific earlyin 1955, Anopinion onthe oceanographic factors was requiredandDr. AllynC, Vine of the Woods Hole Oceanographic Laboratory was called in as a consultant. Dr. Vine's estimate of the movement and dispersion of the radioactive material was compatible with previous calculations, From known current distributions and velocities, it was apparent that the activity measured by the SHUNKOTSU-MARU might be detectable in the far-western Pacific early in 1955. Based on these calcula- tions, Operation Troll was designed to attempt the measurement of residual activity in the Pacific Ocean. On February 1, at a meeting in Washington, Captain Carl G. Bowman of the US Coast Guard made arrangements for use of the cutter TANEY, and February 25 was set as the sailing date. Operational Scientific Personnel The scientific personnel assigned to the operation were Dr. John H. Harley, Chief, Analytical Branch, HASL, responsible for the over-all program and the radiochemical analyses in particular; Dr. Warren Wooster, Scripps Institution of Oceanography, responsible for the oceanographic data and collection of water and plankton samples; Allyn Seymour, University of Washington Applied Fisheries Laboratory, responsible for marine biological work; Robert Gilkey, Scripps Institution of Oceanography, Oceanographic Technician; Robert S. Morse, HASL Chemist; and Rudolph Anker, HASL Electronic Technician. *Measurements were made by coprecipitation with ferric hydroxide and bariumsulfate. This procedure eliminates the natural K 0 activity and loses certain fission products, such as Cs and some of the Ru and Nb,