14 
BUI^LETIN OF THE BUREAU OF FISHERIES 
herring. There was no difference in size between the mature and the immature indi- 
viduals, nor could they be externally distinguished, unless by a certain distention of 
the abdomen in mature specimens, due to the developed testes. It became evident 
from our observations: (i) That a very small proportion of the males of a given year 
develop precociously; (2) that precocity is apparently not caused by the influence of 
peculiar external conditions operating upon the individuals thus affected, but by some 
unknown factor; (3) that precocious development does not stunt the growth. No 
mature female king salmon less than 4 years old have thus far been encountered. 
The commercially valuable portion of the king salmon run consists mainly of 4 and 
5 year fish, with less frequent 6-year individuals. Plate v, figure 9; plate x, figure 18; 
and plate vi, figure 10, represent these three ages. On the Columbia River they are 
roughly grouped at the canneries as “half salmon” and “full salmon.” The half 
salmon consist very largely of 4-year individuals and the full salmon those 5 and 6 
years old, although there is a certain amount of overlapping, as in the sockeye. The 
4-year fish include more females than males, and the 6-year fish are males in even greater 
proportion. It is thus seen that the females are much more uniform in the age at which 
they mature than are the males, being practically limited to their fourth and fifth years, 
while males may develop precociously at any age before the fourth year, or may be 
retarded beyond the usual period. A single male, weighing 67 poimds, observed by Mr. 
N. B. Scofield in the Sacramento River, was in its seventh year. None larger than this 
have been examined, although such are known to occur, so the total range of the species 
may even include 8 years. Anything beyond seven is problematical and beyond eight 
must be considered highly improbable. 
Among the king salmon taken by purse seines in Puget Sound and those taken by 
trolling in the salt water of Monterey Bay, Cal., are found 4-year-old male and female 
individuals which are mature, and others of the same size and age which show no activity 
of the gonads and would not mature until a later year. The same is true of the 5-year- 
old fish, but the undeveloped individuals of this age are more largely males. It seems 
evident that the maturing individuals feed together in the same schools with those which 
are undeveloped and become segregated only when the period arrives for them to seek 
their spawning stream. 
Prof. McMurrich announces, in the recent paper already referred to, that scale and 
otolith structure indicate mature king salmon to be always 4 years old and the grilse 
2 years old. Such a conclusion is on its face highly peculiar and improbable. That 
certain males should mature in their second year as grilse and all others unanimously 
pass their third year without precocious development would be highly remarkable. 
Fully as improbable would be the corollary as regards size in relation to age. As is 
well known, the larger grilse equal or very slightly exceed the smaller salmon of the 
regular 4-year series. Prof. McMurrich’s contention is again based on 'his erroneous 
interpretation of the nuclear area of the scale, taken in connection with the very limited 
amount of material which he examined. Plate v of his paper indicates a typical 5-year 
scale of the stream type, the nuclear portion which he designates fresh-water being 
