The present is based on the measurements of the flying-fish,
Cypserulus agoo (Temminck fi Schlegel), carried out at Tomioka from May to June in 1947. The fishing season of this species is nearly extending from the middle of May to the latter part of June at the said districts. It measures from 170mm to 290mm in body length, being thickly distributed between 180mm and 210mm. But we can not separate some groups from the composition of body length. The body weight shows slso a similar composition to the former in bearing one mode, and we can not recognize some different groups from this.
The average numbers of vertebrae, dosal and caudal fin rays for each group are as follows; namely the first is 45.07±0.1337 (S. E.) ?? 45.69±0.1229, the second 12.90±0.1185 ?? 13.11±0.0743 and the third 9.13±0.0735 ?? 9.33±0.1077.
The fatness, ƒ(=
W/
L3×1000:
W, body weight in g ;
L, bodp length in cm), shows a renge from 12.4 to 20.4 in male and from 13.7 to 19.7 in female. Its mean values of those individuals, which are contained within a range from 190mm to 19.7 in female. Its mean values of those individuals, which are contained within a range from 180mm to 210mm in body length, are 16.2 in male and 16.9 in female, the letter being somewhat higher than the former. Then we calculated the values of
k and
n of each group, which are indicators in a formula,
W=kLn (
W, body weight in g;
L, body length in mm), and got the following results; namely, in male,
k lies from 1.04×10
-4 to 6.47×10
-4. and
n varies from 2.297 to 2.643, while in female,
k is within a range from 2.93×10
-11 to 1.15×10
-3 and
n is extending from 2.154 ao 5.500. Further, we computed the value of log
k for each indvidual, making
n equal to 2.481 in male, an average value of total groups and 2.529 in female, a value obtaimed from total individuals, and made its frequency curve for each sex separately. As a result of this, it shows nearly a normal curve in male, while in female, it bears two peeks. Moreover, it is recognizable that log
k somewhat increases in value in both male and female, as the season advances.
Measuring the weight of gonad, the testes are distributed almost normally, while the ovaries are divided into two groups which differ in the degree of maturity. Comparing the yalue of log
k of the weight of gonad, the former becomes more or xess enlarged in both sexes, as the latter increases. Further, we computed the value of log
k', an indicater of body weight except the gonad, by a similar method to that of log
k', and compared it with the latter. In male, log
k' increases in value with the increment of log k, while en female, the former decreases in value, when the latter becomes over
-4.300.
Sex ratio of each group ( ?? ) varies from 0.27 to 0.66, and is low in value at the middle of the season. The standard deviation of body length of each group (σ) ranges from 0.60 to 1.20, being higher in value at the beginning and the end of the season than at the middle of that. Moreover, σ becomes larger in value, as the body increses in length.
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