Ward. — Migration of the Sockeye Salmon 389 



dealing with so complex a problem, it is frequently valuable 

 to analyze it into subordinate stages, even though they be some- 

 what artificial, and to endeavor to solve part of the question 

 in the hope that such solution may indicate a basis for the 

 solution of the entire problem. 



With this thought in view, I shall confine myself in this 

 paper to that part of the subject which has been primarily in 

 mind in all the investigations which I have carried out in the 

 field. This is the fresh water period in the migration of the 

 Pacific salmon, the life and activities of the fish from the time 

 when, having left the salt water of the estuaries, it is definitely 

 embarked upon the upstream movement. From the time when 

 it begins to ascend the rivers until the time when the eggs or 

 milt have been discharged and the fish dies, it is under the in- 

 fluence of a more definite and restricted environment than that 

 to which it is subject previously. I shall further limit the dis- 

 cussion to a single species of the five that occur on the coast 

 and visit these waters. This is the red or Alaska salmon, 

 Onchorhynchus nerka, also somewhat widely known as the 

 sockeye. This species, being of paramount commercial im- 

 portance because of its numbers and the price it commands in 

 the market, has received considerable attention at the hands 

 of various investigators both in Canada and the United States. 

 It has not however, I think, been intensively studied during 

 this period with reference to the factors that influence its move- 

 ments. 



Possibly at the outset it is wise for me to confess that I 

 agree fully with those who have commented on the very com- 

 plex and marvellous character of the migration. I cannot, 

 however, share their view that such complexity is incompre- 

 hensible or beyond the power of observation and experiment 

 to explain when ultimately all the factors in the situation have 

 been analyzed in their bearing on the movements of the fish. 

 It seems to me fairly well established scientifically that fish are 

 primarily responsive to environmental stimuli, that their ac- 

 tions are due to external influences which may be difficult to 



