38 
BULLETIN OF THE BUREAU OF FISHERIES 
ing. Figures 36 and 37 show scales of immature and mature fish, respectively, 
taken by troll on July 28, 1919. 
FISH IN THEIR THIRD YEAR, STREAM NUCLEI 
The fish of this age group resemble the 2-year-old fish with ocean nuclei in 
that mature females have never been reported. None of these fish taken outside 
was mature, as is apparent from Figure 10. The question of the percentages of 
these fish that will mature during the following year as 4-year fish, and during the 
second subsequent year as 5-year fish, arises here as in the case of the 2-year fish 
with ocean nuclei. As in the case previously considered, it seems probable that 
these 3-year fish with stream nuclei are, on the whole, one year further from maturity 
■IS 
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r 
Va 
N 
re 
[a] 
7fS 
Fig. 10.— Sizes of eggs of females in their third year, stream nuclei. Columbia River and the 
ocean ofl the mouth of the Columbia 
than those in their fourth year. Two-thirds of the 4-year fish v/ith stream nuclei 
were mature, so that it appears probable that approximately two-thirds of these 
3-year fish with stream nuclei will mature during the following year and one-third 
during the second year following. A very few will not mature until they are in 
their sixth year. 
FISH IN THEIR SECOND YEAR, STREAM NUCLEI 
No females of this age group were found in any of the collections, although a very 
few males were discovered. One was taken inside and three outside. Among these 
three, however, two were contained in a special collection, made in 1914, of fish 
selected for their small size — the "grilse." Mature males of this age group are 
extremely rare in the Columbia Kiver and apparently are seldom taken by troll. 
In so far as their maturity is concerned, it seems fair to assume that they will mature 
one year later than the 3-year fish with stream nuclei and two years later than 
the 4-year fish. 
