1m tis ues gives essentially the same results. However, greater : 55 . . . concentrations of Fe in the dark muscle and liver tissues than . ‘ . : 55 in light muscle make the former tissues more desirable for Fe : analysis. 55 . . . The °°? Fe concentrations in dark muscle and liver from Single fish are approximately the same. + The average 137 t 3-4 + ; Cs concentration in the light muscle ofo£ tuna caught north of the equator was 0.15 pci/g dry, with a range from . background to 0.43 pci/g. . tendency for lower 137 . As with 5 c "Fe, , Cs concentrations background to 0.27 pcCi/g) there appeared to be a ; (0.065 pci/g, range, in fish caught south of the equator, but the differences were not statistically significant. The tuna caught near Bikini Atoll contained almost the same average concentration (0.16 pci/g, range, 137 Cs background to 0.31 pci/g as other tuna caught north of the equator, Cobalt-—60 wss not found in light or dark muscle samples of tuna from the Japanese fishery. The limit of detectability with the method used was estimated to be approximately 0.07 pCi/g dry weight. The yellowfin tuna caught off Bikini all. contained small, but measurable, liver tissues. amounts of C86 in the dark muscle and The average value for dark muscle was 1.0 pci/g dry, with a range cf 0.08 to 4.6 pCi/s, a range of 0.21 66 Co to 5.6 pCci/g. . concentration : in and for liver, 1.3, with The correlation coefficient for dark muscle anc : liver was 0.966 a and the - paReTIT