. . ws 60 : 1964 and found that the concentration of Co in the northern population was approximately Pp Pp y five times that in the southern _s population; ws . . 55 . this supports the conclusion that Fe concentrations are generally higher in northern hemisphere tuna than in southern The results of analyses of tissues from the yellowfin tuna caught off Bikini Atoll in 1969 show the large variability that can be encountered even with fish of approximately the same size, caught in the same place within a period of approximately an hour and believed to be from the same school. Certainly the analytical method is not suspect since the correlation for specific activities between tissues is high. One cannot be positive that these fish spent their entire life spans together and were thus exposed to the same water masses, but assuming that they were, there is no evident explanation for the large variability that was found, Blood and liver usually contained the highest concentrations 55 of Log . Fe, but in the highly vascular dark muscle of the tuna the levels were as high as they were in the liver. some importance in future sampling, This may be of as concentrations decrease, V since it is often easier to obtain large samples of dark muscle liver. k O re Vt reported ° . (1965) 2 9 ctry ‘3 fat 19 cT QQ IH ™~ On bey Q 4 © a Folson and Young fe than of a 60 a Co concentration of albacore from the North Poeee got BB ip