GROWTH AND MATURITY OF SALMON IK THE OCEAN 
67 
is quite irregular but is obviously bimodal. It has been possible, by the appli- 
cation of statistical methods, to separate the two component curves with some 
degree of satisfaction, but in view of the fact that the material is selected and 
therefore not representative it seems unnecessary to discuss this in detail. It is 
apparent from the table that all of the fish contained in the group weighing less 
than 5 pounds were immature and that all above 15 pounds in weight were destined 
to mature during the year in which they were taken. 
The percentage of mature and immature fish can not be determined from the 
data available for 1915 on account of the selection involved in making the collection. 
The 1918 collection, although inadequate, gives some indication of the relative 
number of mature and immature fish present in Monterey Bay at the time the 
collection was made. In Table 25 (p. 87) and Figure 24 it is shown that the lines 
separating the two distinctive egg sizes comes at approximately log I) 0.30. With 
the exception of one individual, for which the log D is 0.29, the two groups are well 
separated. If we include this doubtful individual with the group having the larger 
eggs, this group will include 24 individuals and the group with smaller eggs 
will contain 39 individuals. On a percentage basis, then, this collection contains 
38.1 per cent mature and 61.9 per cent immature individuals. This agrees very 
closely with the data from the Columbia River. In Figure 11 the trend of the 
percentage of mature fish taken in the ocean near the mouth of the Columbia 
River shows that on the fiftieth day of the season, June 19, the catch contained 
40 per cent of mature fish. Such a close agreement as this is doubtless accidental, 
but it indicates strongly that the relative maturity of the chinook salmon in Mon- 
terey Bay is, during the latter part of June at least, approximately the same as 
that of the salmon found in the ocean near the mouth of the Columbia River. 
FISH FROM DRAKES BAY AND FORT BRAGG 
A small collection of scales and eggs was made on August 15 and 16, 1918, 
by representatives of the California Fish and Game Commission from fish taken 
by troll in the region of Drakes Bay. This bay is located about 30 miles north of 
the Golden Gate and is one of the centers from which trolling is conducted. Scales 
and eggs from 12 chinook sahnon taken near Fort Bragg were also taken on July 17. 
Since both collections were small, and separate study has disclosed no marked 
differences, they have been combined in the tables presented. Unfortunately serial 
numbers were not given to both scale and egg samples, and it is impossible to 
refer the scales to the corresponding eggs. The length of the fish was recorded 
with the scale samples, and a tag attached to the egg samples also gives the length 
of the fish from which the sample was taken, but except in a few extreme instances 
this does not serve to identify the corresponding samples. Furthermore, the 
number of egg samples does not agree with the number of females. On accoxmt 
of this confusion of the records, a satisfactory analysis is impossible, and it has 
been necessary to handle the data for size of fish and size of eggs separately. 
Table 26 (p. 87) gives the length-frequency distributions for the fish with 
ocean nuclei. In addition to these there were four fish with stream nuclei, all in 
their third year and averaging 64.5 cm. in length. Three of these were females. 
