872 
Fishery Bulletin 95(4), 1997 
eration, freezing, and 10% formalin on the histologi- 
cal quality of samples of ovary from yellowfm tuna. 
He reported that histological quality was best for 
those samples preserved fresh in 10% buffered for- 
malin, whereas samples that had been merely re- 
frigerated could not be used for histology (Itano 1 ). 
Effect of preservation on weight 
The preserved weight of the ovaries from mature fish 
in group B caught in Hawaii was compared with the 
fresh weight of ovaries from mature fish in group B 
(t= 2.565, df=94 and P<0.05) and found to have sig- 
nificantly different means at the 95% confidence 
level. Preserved ovaries averaged a loss of 2% of their 
fresh weight. Our observations ranged from a loss of 
33% to a gain of 11%. 
Samples that were frozen (rc=31) lost, on average, 
6% of their weight and ranged from a loss of 26% to 
a gain of 6% (Fig. 1). In comparison, those that were 
preserved in 10% buffered formalin lost, on aver- 
age, 1% of their weight and ranged from a loss of 
33% to a gain of 11%. The greatest difference in al- 
bacore ovary weight was observed for ovaries weigh- 
ing less than 200 g and which had been frozen, as 
well as for those greater than 600 g and which had 
been frozen (Fig. 1). The greater percent weight 
change observed in the smaller ovaries may be a re- 
sult of processing method. The percentage of weight 
change for samples greater than 200 g, but less than 
600 g, was within 5%. Of the limited number of 
samples (n= 5) greater than 600 g, three of the ova- 
ries that displayed a large loss of weight had oocytes 
that were hydrating and had mean oocyte diameters 
near 1 mm. 
Conclusion 
Freezing was found to have a greater effect on ova- 
rian weight and oocyte diameter than 10% buffered 
formalin. Consequently, the different methods of 
preservation used in comparative studies should be 
evaluated cautiously. Furthermore, a single method of 
preservation or protocol should be used in a given study. 
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