slope of the linear regression was 0.964, or dark muscle tissue can be used for Hence, either liver Co determinations with essentially the same results. DISCUSSION AND CONCLUSTONS It is evident that species such as big eye, blue fin and yellowfin tuna, which migrate througn large areas of the Pacific, are poor indicators of the geographical distribution of radionuclides in the Pacific. On the other hand, Fe from wide areas, good integrators of they are probably and they contain both Fe and higher specific activities greater concentrations of then species that have been successfully used to demonstrate differences in hemisphere, 55 Fe in cod latitudes Preston (1970) from northern (45°-52°N) Fe content of fish from the northern found hicher specific activities of latitu aes (65°-78°N) of the Atlantic in 1967, The highest value found in cod was 220.8 pCi than 1968, 55 in the middle and 1969. Fe/mg Fe at Iceland in 1969 and the average level in the liver of tuna from 11°N in S was during 5 1360 pCi Fe/mg Fe. Maximum levels in tuna caught 1967 and 1968 exceeded 8000 pCi 5 Fe Fe/mg ery, but the levels in most tuna during that pericd wrere less than 2000 pCi bh > Be /mg Fe. or of. 5S BE to 1964, ak Fe levels in Pacific saimon acprorimately 5000 pci 5 (Udcnnings, Fef/mg Fe. 1968), the peak year gives values This value is approximately PoE ARCHIVES