42 
BULLETIN OF THE BUEEAU OF FISHERIES 
shown that during May less than 20 per cent of the fish taken in the ocean are 
mature; during July, between 50 and 75 per cent; and during August, between 
75 and 90 per cent. It has already been mentioned that few data are available 
for September, but those that are available indicate a return to the low percentage 
of mature fish found during the early part of the season. 
PERCENTAGES OF FISH MORE THAN ONE YEAR FROM MATURITY 
Table 8 shows that the percentage of fish taken in the ocean which would not 
mature for two or more years is considerably less than the percentage that would 
matm'e in one more year. The data are not reliable' enough to serve as a basis 
for definite conclusions, but in general it appears that fully two-thirds of the imma- 
X 
✓ / 
<— 
0 "Z Z^a^ci^ 
1 1 1 1 
SO ifo JO 
70 tSo 90 /60 //o y£o y-30 /^a /eo 
Day or >3£Aso/^ 
Fig. 11— Percentage of mature fish taken off the mouth of the Columbia River (exclusive of 
the data from the collection made in 1920) 
ture fish found in the commercial catch would reach maturity during the year fol- 
lowing that in which they were taken. These percentages of immature and mature 
fish obviously do not represent the exact percentages of mature and immature fish 
that go to make up the schools in the ocean, but only the percentages as taken by 
the troilers. Undoubtedly there are much higher percentages of the younger age 
groups actually present outside the mouth of the river than would appear from this 
study of the catch. The taking of the small fish is relatively unprofitable to the 
fishermen if larger ones can be caught, and this would inevitably lead to such a selec- 
tion of gear or of the locality in which the fishing is carried on as would make it 
possible to take more of the larger fish. 
It should be noted that, in designating as "mature" fish taken in the ocean, 
it is not implied that such fish are ready to spawn or even to enter the river. The 
term is used merely to indicate that the individuals would mature and spawn during 
the year in which they were taken. There are many individuals especially during 
the early part of the season that are not ready to begin the spawning migration, 
