ABSTRACT 
This study on bigeye-tuna spawning is based on ovaries from 700 fish collected in the 
central equatorial, western equatorial, and Hawaiian areas of the Pacific. 
A critique on methodology is included, Egg distributions in different parts of an ovary 
and in the right and left members of a pair of ovaries were examined to establish a procedure 
which would give reliable samples for egg diameter frequencies, Two methods of measuring 
eggs were compared for efficiency. The error resulting from the use of ovary weight relative 
to body weight as a measure of the degree of ripeness was estimated. 
Frequency distributions of egg diameters from maturing ovaries are multimodal witha 
maximum of four modes. The size at which the bigeye first spawns was found to be 14 to 20 kg, 
Spawning, which seems to be a year-round occurrence, takes place in the central and western 
equatorial areas but not in the Hawaiian area. There is evidence of more than one spawning 
per year with the number of eggs per spawning ranging from 2.9 to 6,3 million. 
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