"MOT FOR PUBLICATION PRELIMINARY REPORT Decline of gross beta radioactivity in fishes at 410844 Rongelap Atoll to March 1958. (| f This report extends the observations on Rongelap fishes beyond that of Welander (1957) up to the spring of 1958 before the series of detonations of this year, and shows the trends on a log-log, rather than a semi-log basis. | Results appear separately in Table 1 and Figures | and 2 for liver, bone, and muscle of fishes at Kabelle and Rongelap Islands, and in Rongelap Lagoon chiefly in the vicinity of Rongelap Island. Data are most plentiful for Kabelle Island where four full years are represented, while at the other localities shown observations were not begun until nearly a year after the detonation of March 1, 1954 at Bikini Atoll. At Kabelle and Rongelap Islands the last two observations are for July 1957 and March 1958. It will be noted that the decline during this period was greater at Rongelap Island than at Kabelle Island, bringing the present levels in uc/kg of wet tissue at south and north ends of the atoll to about 0.01 amd 0.1 respectively. Kilthauw- Bonkan Auguel 5 (95S Ff y yas | DOMARCHIVES °,,