102 
PACIFIC SCIENCE, VoL VIII, January, 1954 
TABLE 2 
Comparative Abundance of Ova Modal Groups 
OF Various Diameters in the Samples Taken 
FOR THE Summer of 1949 
MODAL DIAMETER OF THE 
GROUP OF LARGEST 
OVA FOUND 
PERCENTAGE OCCURRENCE 
OF OVARIES WITH SUCH OVA 
GROUPS IN THE SAMPLES 
Millimeters 
0.48 
5 
0.60 
30 
0.68 
55 
0.80 
6 
0.88 
4 
progressively less available to the fishermen 
until a short time after spawning and that 
when they again enter the catch the dominate 
ova diameters in their gonads are 0.4 to 0.5 
millimeter. In turn, these ova may grow and 
mature and the spawning cycle repeat itself. 
Inasmuch as the data do not include informa- 
tion concerning the histories of individual 
fish but represent a statistical cross section 
of the ovarian situation at various irregular 
stages for various fishes, it is difficult to ob- 
tain a valid basis for judging the rates of 
growth of ova and the number of times fish 
may spawn. If the spawning act was a periodic 
matter, occurring at the same time for all fish, 
it would be possible to judge when it oc- 
curred and how often; however, if it occurs 
irregularly with relatively small groups of fish 
spawning together as the ova mature, data 
of the nature obtained during the present 
study cannot adequately describe the situation. 
SIZE OF FISH AT MATURITY 
The smallest fish that possessed maturing 
ova during the spawning season were around 
40 to 45 centimeters long. Eish 35 to 40 
centimeters in length had ovaries that, with 
a few exceptions, seemed immature. Immature 
fish are rare in the commercial landings during 
the spawning season, as are likewise fish less 
than 40 centimeters in length. It therefore 
appears likely, considering also the informa- 
tion on age and rate of growth, that aku may 
mature in 1 year. 
SEX RATIOS 
The sex ratios obtained while sampling ova- 
ries are of interest in that a significant depar- 
ture from an expected 1 : 1 ratio occurs in the 
fall months. 
The number of male and female fish ob- 
tained during the course of this sampling, 
together with the probability that the ob- 
served sex ratio was 1:1 as indicated by chi- 
square, is given in Table 3 for spring, summer, 
and fall. 
The significant change in the sex ratio 
which occurs during the period from Sep- 
tember through December corresponds to the 
nonspawning period (see Fig. 3) and may 
indicate a differential availability between 
male and female fish during this period. This 
TABLE 3 
Comparison of Sex Ratios of Aku for Spring, Summer, and Fall, 1949 and 1950 
1949 
1950 
MARCH 
JUNE 
SEPT. 
MARCH 
JUNE 
SEPT. 
TO 
TO 
TO 
TO 
TO 
TO 
MAY 
AUGUST 
DEC. 
MAY 
AUGUST 
DEC. 
Males 
237 
691 
351 
42, 
275 
418 
Females 
205 
722 
214 
40 
240 
316 
Totals 
442 
1,413 
565 
82 
515 
734 
Probability 
.13 
.41 
<.0001 
.82 
.12 
<.001 
