158 
PACIFIC SCIENCE, Vol. XV, January 1961 
The strontium units for the liver of coconut 
crab of earlier collections from Rongelap have 
been reported previously (Applied Fisheries 
Laboratory, 195 5^, 1955£; Dunning, 1957). 
In order to report the strontium units for the 
March, 1958, collection, Table 5 has been in- 
cluded. 
Since the results of these studies show that the 
fat content is variable and the fat fraction con- 
tains practically no minerals or radioactivity, 
radiochemical analyses of the liver of coconut 
crab should be made on the basis of nonfat solids 
rather than on the entire liver, as has been done 
in the past. 
SUMMARY 
The values for strontium-90 and gross beta 
activity in the fat and nonfat fractions from the 
livers of 12 coconut crabs ( Birgus latro ) col- 
lected at Rongelap Atoll during March, 1958, 
are presented. 
Although fat constituted an average of 47 
per cent by weight on a wet weight basis (74 
per cent on a dry weight basis), gross beta 
activity of the fat fraction amounted to less than 
0.5 per cent of the total activity on a wet weight 
basis. Fat content on a wet weight basis had 
a range of 31 to 65 per cent. There is a linear 
relationship between strontium-90 activity and 
gross beta activity. Since the fat content of 
coconut crab liver is variable and the fat fraction 
contains practically no radioactivity, it is sug- 
gested that the radioactivity (and mineral con- 
tent) of liver samples be compared on the basis 
of the nonfat solids. 
/ 
ACKNOWLEDGMENT 
The authors wish to thank Dr. E. E. Field of 
the Laboratory of Radiation Biology, University 
of Washington, for his willing assistance and 
most helpful suggestions in the course of this 
investigation. 
REFERENCES 
Applied Fisheries Laboratory (University 
of Washington). 1949. Bikini Radiobiolog- 
ical Resurvey of 1948. U. S. AEC Report 
UWFL-16. 
TABLE 5 
Strontium Units and Calcium in Liver of the Coconut Crab ( Birgus latro ) 
SAMPLE 
LOCATION OF 
Sr 90 d/m /g 
mg. Ca/g 
STRONTIUM 
NUMBER 
COLLECTION 
WET WEIGHT BASIS 
WET WEIGHT BASIS 
UNITS* 
34 
Rongelap Atoll.-. 
55 
7.25 
3448 
35 
90 
10.03 
4079 
36 
Kabelle Island 
130 
23.93 
2469 
37 
194 
15.72 
5609 
38 
134 
17.18 
3545 
Mean 
121 
14.82 
3830 
Standard deviation 
52 
6.51 
1152 
84 
Rongelap Island.. 
40 
8.39 
2167 
85 
30 
5.40 
2525 
86 
46 
12.67 
1650 
87 
47 
6.18 
3457 
88 
65 
10.99 
2688 
Mean 
46 
8.73 
2497 
Standard deviation 
13 
3.09 
668 
61 
Eniaetok Island... 
70 
8.00 
3977 
62 
87 
7.22 
5477 
Mean 
79 
7.61 
4727 
Standard deviation 
12 
0.55 
1055 
* Strontium unit = micro-microcurie of Sr 90 per gram of calcium. 
