GROWTH AND MATURITY OF SALMON IN THE OCEAN 
39 
In the preceding discussion of the various age groups, no attempt has been 
made to show the percentage of mature and immature fish in each, nor the percent- 
age which the immature fish formed of the total number in the different collections. 
These data have been compiled in separate tables for ease in making comparisons. 
Table 5 shows, for each collection of fish taken inside the river, the percentages of 
the total number of females which are composed of the mature and immature 
fish of the different age groups. Table 6 gives similar data for the collections of 
fish caught in the ocean. A discussion of the composition of the entire collections 
as regards age groups will be given later, but attention is first directed to a discus- 
sion of the age groups most commonly rejDresented among the immature fish. 
AGE OF IMMATURE FISH 
Reference to Table 5 shows, as would be expected, that very few immature 
fish are taken inside the river. It has already been explained (page 34) that a few 
immature fish are occasionally taken in the lower part of the Columbia River 
estuary. The collections of May 17 and 18, July 3, and July 7 were all made in this 
part of the river and are the only ones to contain immature fish. Such immature 
fish as were taken belong to the 2 and 3 year groups with ocean nuclei and to 3 and 
5 year fish with stream nuclei. 
Table 5. —Percentages of females of different age groups and different degrees of maturity taken in 
the river at different times during the season ' 
Date 
Ocean nuclei in- 
Stream nuclei in — 
Second 
year 
Third year 
Fourth 
year 
Fifth 
year 
Sixth 
year 
Third 
year 
Fourth 
year 
Fifth year 
Sixth 
year 
I. 
I. 
M. 
M. 
M. 
M. 
I. 
M. 
I- 
M. 
M. 
May 10 
4. 5 
11. 1 
72.8 
62. 2 
77.8 
8.8 
14. 8 
84.0 
18.2 
52. 0 
35.4 
18. 5 
7.8 
2.4 
8.7 
22. 7 
26. 7 
22.2 
79.5 
33.4 
16.0 
36.3 
36. 0 
41. 7 
11. 1 
2.0 
2.4 
4.3 
May 13 _ 
May 16 
May 17 and 18 
2.9 
44. 5 
2.9 
6.9 
May 27 
7.4 
May 30 and 31.. _ 
June 10 
4.5. 5 
8.0 
20.8 
11. 1 
33. 3 
19. 5 
39.2 
65.2 
20.0 
34. 2 
7.3 
9.5 
June 16 
2,0 
2.0 
June 16 and 17. 
2. 1 
40.8 
47.0 
48.8 
41.3 
34.8 
80.0 
55. 3 
ei. 1 
57. 2 
June 24 and 25 
14.8 
5.9 
3.7 
Julys.... 
2.0 
2. 4 
4.3 
2.0 
9.8 
July 7.... _. 
12.2 
2. 4 
July 16.... _ 
2.2 
July 28.... _ 
Aug. 5... .. . 
Aug. 6 
7.9 
7.3 
7. 1 
2. 6 
2.4 
7. 1 
Aug. 22.. 
19. 5 
Ifi. 7 
2.4 
2.4 
Sept. 12 
1 The initials I. and M. stand for immature and mature, respectively. 
Among the fish taken in the ocean (Table 6), it is seen that by far the greater 
part of the immature fish are in their third year, with ocean nuclei. Fish in their 
second year, ocean nuclei, are the next most important component. Fish in their 
third year, stream nuclei, come next in importance. In addition to these age 
groups, which include the greater part of the immature fish taken, a few immature 
