100 
PACIFIC SCIENCE, VoL VIII, January, 1954 
Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. 
Fig. 3. Average modal diameter of the largest group of ova present in ovary samples for 1949, 1950, and 1951 
of the space lateral to the visceral mass. The 
ovaries become bright yellow, deepening al- 
most to orange in very mature specimens. 
The small eggs can be seen clearly through 
the ovarian membranes, and the small blood 
vessels become increasingly prominent in such 
fish. The testes of mature males are smooth 
in texture, pure white, and of more fragile 
texture than the ovaries. The sex of a mature 
or maturing fish is easily determined by a 
gross examination of the gonads. 
The ovaries of spawned-out females usually 
appear large but flabby and empty, are often 
dark and somewhat bloody, and contain a few 
large disintegrating ova. 
Eully ripe fish were very rare in the landings; 
such fish are apparently not commonly avail- 
able to the fishery. One fish 43.2 centimeters 
long, examined on June 20, 1947, appeared 
to be fully mature. When it was opened, a 
gelatinous mass of eggs came foaming out of 
the visceral cavity in sufficient quantity to 
make a fair double handful. These eggs, as- 
sumed to be mature, were the largest seen in 
quantity in any of the gonads observed, aver- 
aging about 1.125 millimeters in diameter. 
They were smooth and round (or slightly 
oval) and contained a single yellow oil glob- 
ule which varied from 0.22 to 0.45 millimeter 
in diameter. In contrast, the larger ova from 
maturing aku as taken by the commercial 
fishery measure only from 0.4 to 0.9 milli- j 
meter in diameter and have a cluster of two !| 
or three oil globules. 
The beginning of the spawning season was 
not observed in 1948, as the program of taking 
ova diameters and ovary weights revealed that 
the fish sampled at the beginning were as 
mature as ordinarily are available to the fish- 
ery. From the beginning of the program, June 
16, 1948, until the middle part of September, 
spawned-out fish were also very rare; after 
that time they dominated the catch. 
However, the spawning season studies did 
