GROWTH AND MATURITY OF SALMON IN THE OCEAN 23 
Table 1. — Relation between diameter of eggs and size of fish (Columbia River chinook salmon) 
Age group 
Date taken 
Number 
of speci- 
mens 
Average 
length in 
centimeters 
(L) 
Average 
logarithm 
of egg 
diameter 
Geometric 
mean of 
diameters 
of eggs (I>) 
in milli- 
meters ' 
DXlOO 
In third year, stream nuclei, immature 
In third year, ocean nuclei, immature. 
In fourth year, ocean nuclei, mature. 
In fifth year, ocean nuclei, mature. 
May 8 to 10 , 
June 4 _ 
July 2.. 
July 28 
August and September 
May 8 to 10 
June 4 
July 2 
Aug. 13 
Sept. 18 to 19 
May 10 
June 21 
July 2.. 
July 28 
Aug. 13.. 
May 18 
July 2 
July 28 
Aug. 13 to 17 
18 
11 
7 
7 
4 
100 
32 
26 
48. 11 
50. 40 
56. 00 
59.00 
66. 00 
61.00 
61.61 
66. 50 
70.33 
70. 72 
79. 56 
86.40 
84.19 
89.33 
93. 50 
96. 15 
95.40 
96. 22 
100. 16 
1. 9588 
1.9480 
.0214 
.0756 
. 1150 
.1043 
.0981 
.1085 
. 1430 
. 1500 
.3174 
.5100 
.5336 
.6406 
.7243 
.4054 
.5792 
. 6733 
.7553 
0. 909 
.889 
1.050 
1. 190 
1.303 
1.272 
1.254 
1.284 
1.390 
1.412 
2.075 
2. 542 
3. 796 
4.712 
5. 695 
1.890 
1.763 
1.909 
2. 017 
1.975 
2.085 
2.035 
1.930 
1.977 
1.998 
2. 610 
3. 740 
4.055 
4. 890 
5. 670 
2.645 
3. 978 
4.900 
5. 680 
1 The geometric mean of a series of measures is the number corresponding to the arithmetic mean of the logarithms of the 
original measures. Since the data on egg sizes has been handled in the logarithmic form (see pp. 24 and 25), it is convenient to 
use here the geometric rather than the arithmetic mean. 
The ratio, ^ '^J'^^ , given in the last column of this table, is 10 times the per- 
centage of the length of the fish represented by the diameter of the eggs. The 
actual percentages are so small that it is more convenient to handle the values in 
this way. 
The table shows that among the immature fish there is little variation in the 
relative size of the eggs as compared with the size of the fish. The ratio is prac- 
tically the same in immature fish of the different age groups, and within a single 
age group there are no significant changes in the ratio during the season. This 
signifies that the size of the eggs and their growth is closely proportional to the 
size and growth of the fish. In the case of the mature groups, however, a constant and 
X 100 
marked increase in the ratio ^ — is clearly shown as the season advances — 
an increase which is indicative of a distinct differential growth, resulting in the 
rapid increase in the relative size of the eggs as maturity approaches. 
In May there is comparatively little difference in the relative size of the eggs 
of the mature fish and those of the immature fish. The value of the ratio for 
immature fish is very close to 2.0, and in May the ratio for mature fish is only 
about 2.6. During the season, however, the value of the ratio in the case of the 
maturing fish steadily increases until it is nearly three times as large as that for the 
immature fish. Evidently the differential growth of the eggs, which takes place 
during the last year, has not progressed far by May. Scale examinations show 
that the new growth of the year, if apparent at all, is at this time just beginning 
to show as a distinct band of wider rings at the margins of the scales. (See figs. 38, 
