11 



fry were put in Bear Valley Creek, which is dammed at its lowest end 

 and fixed with a screen so that the fish cannot get out. Here, eleven 

 months after planting, two salmon were caught, each measuring 5.5 

 inches. At the same place, fifteen months after planting, two speci- 

 mens were caught, one 6 inches, the other 7.5 inches long. This remark- 

 able growth in a stream where they were, confined is another point that 

 leads to the belief that the salmon which preferred to remain, after 

 four months, in the streams where they were not confined were individ- 

 uals stunted or the physical inferiors of those running out during the 

 first four months. 



The growth of the salmon was the same in Paper Mill, Nicasio, and 

 Olema creeks, but in Hatchery Creek the growth was not so rapid. 

 The salmon in the lower end of the creek grew rapidly enough, but 

 those above grew very slowly, gaining on an average the first three 

 months only .15 of an inch per month. At the end of the fourth 

 month they had all descended to the lower stream. The reason of this 

 slow growth in the upper stream was due to the scarcity of food. 

 Although the temperature of the water there is much lower than it is 

 below or in the other streams, we cannot, knowing what we do of their 

 growth in other cold streams, attribute their slow growth to the tem- 

 perature of the water. 



Owing to this difference in growth in the same stream, the variation 

 in the size of the individuals is great. Out of thirteen specimens taken 

 from lower Hatchery Creek at the end of three and one-half months, 

 the largest was 3.53, the smallest 2.26 inches, a difference of a little 

 over 1.25 inches; or, expressed in the amount gained by each since 

 planting, the largest 2.18 inches, the smallest 0.91 of an inch. The 

 variation in Olema Creek, where no difference was found between the 

 upper and lower stream, after the second month was nearly as great. 

 From seventeen specimens taken at the mouth at the end of three 

 months the largest was 3.42, the smallest 2.58 inches. 



The important points learned in connection with the rate of growth 

 of the young salmon were : First, that during the first four months 

 their growth averaged 0.52 of an inch per month ; Second) that the few 

 salmon remaining in the stream after four months were stunted, and 

 grew very slowly in comparison with those confined in Bear Valley 

 Creek. 



An important fact to be noted in connection with the salmon confined 

 in Bear Valley Creek is, that of the two salmon taken in February, 

 1898, both were males; one with the generative organs fully developed. 

 It is not uncommon to find young 4 to 4| inch male salmon remaining 

 in the streams with the testes fully developed, but it was never before 

 found in a salmon whose age was known. This individual found in 

 Bear Valley Creek was 5.5 inches in length, and was just twelve months 



