which includes small fish, invertebrates and algae. Table 2 contains data on the rate of decline of the beta radioactivity in reef fish collected at Rongelap and Ailinginae Atolls between March 26, 1954 and July 18, 1957. The rates of decline in liver, bone muscle tissue of fish from Kabelle Island are givenin Figure 1. and The decline rates are similar for all three tissues, especially during the first two years. Recontamination by other nuclear devices during the summer of 1956 is indicated by the increase of radioactivity in muscle ald bone and a temporary decrease in rate of decline in liver tissue. At present, the radioactivity in liver tissue appears to be declining at a more rapid rate than in bone or muscle, while the radioactivity in the viscera or stomach contents has declined more rapidly than that of other tissues (Table 2). It has been suggested (Welander, 1957) that some of the long-lived isotopes may be accumulating in the bone and muscle of fish, whereas the radioactivity in liver tissue is similar to that in the stomach, bearing out the fact that the liver is an organ for the temporary storage and passage of food and waste products. It is of interest to note that the levels of radioactivity in the bone and muscle are about the same as those of the 1955 samples. Data on radioactive decay were obtained from bone andliver tissue of groupers (Epinephalus merra) from Kabelle and Rongelap Islands, and from homogenized muscle tissues from 13 species of reef fish. The decay rates | of muscle and bone (Figure 1) are more rapid than decline rates for the . rh AR: ENTS fe