GROWTH AND MATURITY OF SALMON IN THE OCEAN 69 
in their third, year with ocean nuclei. Group 3 (the mature individuals) is evidently 
composed mainly of fish in their fourth and fifth years. 
Table 15. — Chinook salmon taken by troll near Drakes Bay and Fort Bragg, Calif., July and 
August, 1918, tabulated to show correlation between size of eggs and length of fish 
Logarithm of diameter of eggs (mid-value of 
class) 
Centimeter length (mid-value of class) 
Total 
45 
55 
65 
75 
85 
95 
105 
1.85.. _ __ 
3 
3 (Group 1; 3 individuals). 
SHGroup 2; 18 individuals). 
8| 
3) 
^HGroupS; 43 individuals). 
64. 
3. 
18. 
43. 
.05 _ 
1 
4 
4 
1 
2 
.15 - 
1 
1 
4 
3 
4 
5 
.25 - 
.46 
.65 
1 
3 
10 
5 
2 
8 
2 
.65 : 
.75- 
Total - 
Group 1 --- 
3 
3 
1 
9 
4 
17 
18 
12 
Group 2. .. . - - 
1 
9 
3 
1 
5 
12 
Groups - ... . 
18 
12 
Females of scale collection tabulated according to length and age 
Second year 
3 
3. 
Third year. 
8 
3 
8 
19. 
Fourth year 
1 
2 
17 
10 
30. 
Fifth year 
1 
1. 
Total... 
3 
8 
4 
10 
17 
11 
53. 
SUMMARY AND CONCLUSIONS 
1. It has been shown that the eggs of female chinook salmon undergo a well- 
marked differential growth during the growing period just preceding and terminat- 
ing in the migration. As a result, those females which are destined to spawn 
during the year in which they are captured may be distinguished by the size of 
their eggs from those which will not mature for at least one more year. 
2. Using the size of the eggs as a criterion, the commercial catch of salmon 
taken in the ocean near the mouth of the Columbia River has been analyzed and 
the percentage of mature and immature fish determined. It has been found that 
the percentage of mature fish taken in the ocean varies greatly during the season, 
being relatively small (from 10 to 20 per cent) in May but increasing gradually, 
until in August nearly 90 per cent are mature. While in general, as would be ex- 
pected, fish taken within the Columbia River are mature, there are times when a 
few immature fish are taken by seines and traps in the extreme lower part of the 
estuary. The few data from Monterey and the northern coast of California are 
in substantial agreement with those from the region of the Columbia. 
3. The immature fish taken in the ocean comprise, in the order of relative 
abundance, the following age groups: Third year, ocean nuclei; second year, ocean 
nuclei; third year, stream nuclei; fourth year, ocean nuclei; fourth year, stream 
nuclei; and fifth year, stream nuclei. 
