72 BULLETIN OF THE BUREAU OF FISHERIES 



been reported from this district in the odd years. Whether this is due to the com- 

 plete failure of the run or whether there is some economic explanation we have no 

 way of knowing. Inquiries have been made of some of the companies operating at 

 Nushagak, but they have been imable to offer any acceptable explanation of the 

 phenomenon. The trend of the even-year catches at Nushagak rose rapidly to the 

 level of 800,000 in 1904, where it remained remarkably constant for over a decade. 

 In this case, however, the level of the trend is determined very largely by the two 

 exceptionally large catches of 1906 and 1912, and the method of determining the 

 trend has so spread these large catches that the constancy of the level is especially 

 marked. The catch during the even years from 1914 to 1920 remained fairly con- 

 stant and at a level above that of the preceding years, with the exception of 1906 

 and 1912. The trend for these years (1914 to 1920) is somewhat lower, however, 

 but this is due to the influence of the two exceptional catches. Since 1920 the even- 

 year catches have been poor, but those for 1924 to 1926 were influenced by the 

 regulations, as mentioned above, and that for 1922 possibly was influenced by the 

 economic factors that operated to reduce the pack of 1921 throughout Alaska. It 

 does not appear from these data that the pink-salmon run of the even years has been 

 depleted. In this connection it should be noted that if the parent-stream theory 

 holds as rigidly in the case of the pink salmon as in the case of the reds, the pinks 

 would be expected to show the effects of over fishing very promptly. 



The catch of pink salmon at Kvichak is much smaller than at Nushagak but 

 shows similar extreme fluctuations and the same two-year cycle with good catches in 

 the even years and poor catches in the odd. In only two of the odd years were any 

 significant catches of pink salmon recorded — 1915 and 1917. The general trend of 

 the catches in the even years was approximately level until 1918; then came the 

 remarkable catch of 1920, and since then the catch has been insignificant; but the 

 catch of the years since 1922, as at Nushagak, has been affected by the regulations, 

 and it seems possible that the catch of 1922 was reduced by economic causes. So 

 here, again, we have no evidence of depletion in the pink-salmon run. 



We have not calculated the trends for the other three species, believing that the 

 graphs are sufficiently clear. The catch of cohos at Nushagak shows a gradual 

 increase up to about 1916. Subsequently a somewhat lower level was maintained 

 until 1922, since which year the catch has been lower than at any tune since 1901. 

 The cohos as well as the pinks run late in the season, and there is no doubt that the 

 closing of the season on July 25 has been responsible for the reduced catch of cohos 

 in the years following 1922. It is possible that some depletion is shown by the re- 

 duced catches in the years 1917 to 1922, inclusive, but this is by no means certain. 



In the case of the king salmon there appears to have been a slight reduction in 

 the catch at Nushagak since 1916, but the catch at Kvichak does not seem to have 

 been affected similarly. The catch of kings has not been affected so much by the 

 regulations, however, as provision is made for the use of king-salmon nets not less 

 than 8^ inches stretched mesh previous to June 25, when the season begins in which 

 red salmon may be taken. 



The catch of chum salmon at Nushagak reached a maximum in the years from 

 1914 to 1918 and since then has maintained a decidedly lower level. On the Kvichak 

 side no general change has occurred. The effect of the regulations is apparent again 



