BRISTOL BAY AND AL-iSKA PENINSULA SALMON STATISTICS 



71 



for the series of odd and even years, therefore, and have shown these two distinct 

 trends on the graphs. These trends represent a moving average of three years in- 

 stead of five, as used in the case of the red salmon, as the use of a five-year average 

 would have shortened our trend imduly. 



In general, throughout western and central Alaska the pink salmon run much 

 more heavily in the even years than in the odd. This is shown clearly in the graphs 

 for both Nushagak and Kvichak by the conspicuous "peaks" that occur, with very 

 few exceptions, in the even years. The size of the catches, especially in the even 

 years, varies tremendously, as is exemphfied particularly well by the catch of over 



FiQ. 10.— Catch of pinks, chums, and kings at Kvichak 



950,000 pinks at Kvichak in 1920 — approximately three times the next largest catch. 

 The catch of pink salmon in Bristol Bay has been largely affected by the regulations 

 that have been in effect since 1922. These regulations have closed the fishing season 

 on July 25, and as the pink-salmon run occurs mainly after this date the catch of 

 this species has been reduced materially. 



The trends of the catches of pink salmon in the odd and even years show some 

 interesting variations, both at Nushagak and Kvichak. In both locahties the trend 

 for the odd years is distinctly below that for the even years, as would be expected. 

 The odd year trend at Nushagak rises gradually to a peak in 1905, then declines 

 gradually to an abrupt termination in 1913. After that date no pink salmon have 



