66 
BULI^TIN OP THE BUREAU OF FISHERIES 
RELATIVE MATURITY 
In the matter of relative maturity the salmon of Monterey Bay do not di£fer 
greatly from those taken off the mouth of the Columbia River. The distribution 
of egg sizes, as found in the collection of eggs made in 1915, is given in Table 23. 
In this table the egg sizes are given separately for the three size groups mentioned 
above — that is, for the fish less than 5 pounds in weight (Group 1) , for those between 
5 and 15 pounds (Group 2), and for those over 15 pounds (Group 3). Group 2 is 
composed largely of fish in their third year with ocean nuclei, and the distribution 
of egg sizes in this age group has been shown separately in Figure 3. Table 25 
gives the distribution of egg sizes as found in the 1918 collection. Figure 24 shows 
• /,ao -I.90 OOP o.io o.zo 0.30 0.40 o.so o.eo o, to 
Logarithm of I)iAMeTCR of Eggs 
Actual DiAMETE.f1 of Eggs mm. 
O .ej 0.75 A£ /,g5 / S 1.75 Z.O Z.S 3,0 3,5 1,0 4.5 S.O, 
Fig. 24. — Distribution of egg sizes as found in two collections made at Monterey, Calif. 
the distribution of egg sizes for both the 1915 and the 1918 collections. The general 
appearance of the two distributions is quite similar, although many more mature 
fish were taken in 1915 than in 1918, probably due to the selection involved in 
making the first collection, which has been mentioned above. A distinct bimodahty 
is apparent in both collections. One mode appears in both at log J) 0.17 and another 
at log B 0.39. The two modes in the distribution of egg sizes in the fish in their 
third year with ocean nuclei, as shown in Figure 3, are at the same points. Of 
the two groups shown in Figure 24 the fish with the larger eggs would undoubtedly 
have matured during the year in which they were taken, while the others would 
not have matured for at least one more year. There is obviously a certain amount 
of overlapping, which is especially evident in the 1915 collection. An examination 
of Table 23 on page 86 shows that the overlapping is entirely within the group of 
fish weighing from 5 to 15 pounds. The distribution of egg sizes within this group 
