detectable amounts would be found, and that their chemical behavior was well enough known to permit a meaningful analysis of the data when obtained (Bowen and Sugihara, 1958} Too few samples have been analyzed so far to permit a reliable interpretation of the results. Although sr? may be more abundant in the Pacific Ocean in the vicinity of the Eniwetok Test Site than in the Atlantic Ocean the occurrence of sr?? in the marine organisms of the Pacific is not common. The low levels of radiostrontium in fish and other marine organisms were pointed out in the 1957 hearings Revelle, 1957) (Alexander, 1957; and have been substantiated by additional analyses since that time. If radiostrontium is present in the marine bio- logical samples it is usually in the samples collected during the first few days after fallout when many of the other fission products that are not found in samples collected at a later time are also present. The presence of a broad array of fission products in the samples immediately after fallout is believed to be, tially, an adsorption phenomenon. at least par- Radioisotopes are present in particulate form immediately after fallout and when in this form the most effective concentrators of activity are the mucous, ciliary and pseudopodial filterers is (Schaefer, 1957). Lowman (1958) also in agreement with the postulate that the major source of radioactive elements from fallout to marine zooplankton is through the uptake of particulate material.