32 BULLETIN OF THE BUEEAU OF FISHERIES 
group of 4-year fish with ocean nuclei that had the smaller eggs, and was found to 
be 2.24.^ This is somewhat larger than is characteristic of immature fish (about 
2.0), but it is nearer this figure than that which is characteristic of mature fish taken 
in May (2.6). 
Table 4. — Chinook salmon taken by troll off the mouth of the Columbia River, May 17 and 18, 1920 
[Females in their fourth year, ocean nuclei, tabulated to show correlation between length and size of eggs] 
Logarithms of diameter of 
eggs (mid-value of class) 
Centimeter length (mid-value of class) 
Total 
73 
75 
79 
81 
S3 
85 
87 
89 
91 
93 
95 
97 
99 
0.21.. 
1 
1 
.23-. - -- 
1 
1 
1 
1 
4 
.25 
1 
3 
1 
5 
.27. __ _ 
2 
1 
3 
.29 
1 
1 
.■iZ** ---- 
1 
1 
.35 
i 
1 
2 
.37 .... 
1 
1 
1 
2 
5 
.39 _- 
2 
2 
.41 
1 
1 
.43- - ---- 
1 
1 
2 
.45 
1 
1 
1 
3 
.47 -- 
2 
2 
.49- -. 
1 
1 
.5.';*--- — 
1 
1 
1 
3 
Total 
1 
2 
6 
9 
4 
4 
4 
3 
2 
1 
36 
The relatively slight differences noted between the size of the eggs of the mature 
and those of the immature fish in this collection are probably associated with the 
fact that the collection was made in 1920, while most of the collections that have 
been made the basis for this study were made in 1919. It is not improbable that 
the differential growth of the eggs, wliich takes place during the last year (and 
which has been shown to be mainly responsible for the observed difference in the 
sizes of the eggs of mature and immature fish), may begin at different times in 
different years. It should also be noted that the fish taken in the ocean during 
1920, which were available for study, were selected, very few being under 8 poxmds 
in weight. Laws passed by the Washington and Oregon Legislatures prevented 
the sale of immature salmon under this weight, so that few of the smaller fish found 
their way to the canneries. This factor alone, by tending toward a selection of 
gear that would take the larger fish, might well be responsible for the difficulty en- 
countered in determining the relative maturity of the fish found in this collection. 
In most of the other collections no particular difficulty has been encountered 
in determining the relative maturity, but the percentage of immatiu"e fish is, as 
has already been mentioned, much lower than would naturally be expected. Figure 
30 shows a scale from one of the immature fish of this age group taken on August 13, 
1919, and Figure 31 a scale from one of the mature fish taken at the same time. 
FISH IN THEIR THIRD YEAR, OCEAN NUCLEI 
The distribution of egg sizes during the season for the fish that are in their 
third year, with ocean nuclei, is shown in Figure 6. The difficulties encountered in 
177 2 
3 Average log D=0.2485. Geometrical mean of the diameters=1.772 mm. Average length=79cm. liiir=2.24. 
