12 



old. It should also be noted that it was no smaller than the other male 

 salmon taken at the same time. Evidently the development of the 

 sexual organs did not retard its growth. 



Although these young male salmon are occasionally found with the 

 generative organs prematurely developed, no females, to the best of my 

 knowledge, have ever shown such development. This premature 

 development peculiar to the males, accounts for the undersized males, 

 or u grilse," accompanying each run of salmon up the rivers, and it 

 tends to prove that such "grilse" are not stunted individuals, but 

 simply that they have matured at an earlier age and are younger than 

 the salmon which they accompany. 



The following is a mere speculation in regard to the age 



THE AGE of the above mentioned "grilse": We have already seen 



OF THE that one out of the two males taken in Bear Valley Creek 

 "GRILSE." at the age of one year was sexually mature. In the 

 headwaters of the Sacramento we have in November 

 found among the young salmon remaining in the streams several 

 sexually mature males, which at that time were under ten months of 

 age. These few examples which have come to my notice represent a 

 very small percentage of the number that must mature within ten 

 months or a year in the large body of salmon that leave the stream 

 immediately after hatching. Reaching maturity they would naturally 

 follow the next run of salmon up the river. There are two runs of 

 salmon up the Sacramento each year ; the fall run starting up the river 

 about the end of July and reaching the spawning beds at Battle Creek in 

 October. The eggs spawned by this run hatch in January and February. 

 Ten months after hatching, at which time the "grilse" would have 

 matured, would be too late for them to catch the next fall run up the 

 river, but they could catch the next spring run, which starts up the 

 river in April, and reaches the spawning grounds in the McCloud River 

 in June and July, the eggs hatching in October and November. The 

 salmon hatching from this spring run get out of the river in time for 

 the "grilse" to catch the fall run ten months later. 



If this is true the "grilse" running in the spring are about sixteen 

 months of age on reaching the spawning beds in June. Those arriving 

 on the spawning beds in the fall are about twelve months of age. If 

 this actually happens, the "grilse" of the spring run should average 

 larger than those of the fall run. The age of these "grilse" can be 

 determined by better and more extended observations, and such 

 knowledge would be a long step toward determining the important 

 question of how old the full-grown salmon are whe*n they run. 



