CENTRAL AND WESTERN ALASKA INVESTIGATION. 155 



The mere statement of the case disproves it. Even the tributaries 

 of one river vary widely year by year in the proportion of the total 

 run which enters each of them. If tliis be true of the tributaries of a 

 single river, how much more probable of four separate rivers, which 

 join only at their mouths. It is certain that they would vary inde- 

 pendently and that the oscillation might be of large dimensions. 

 Due to manner of fishing, one of these rivers might experience a 

 progressive reduction of its run that was not felt by the others. 

 Prior to 1908, the Wood River fish ran the same gantlet in the outer 

 bay as did those bound for the other rivers, and in addition were 

 subjected to further reduction by traps and gill nets operating the 

 entire length of Wood River. The main Nushagak and the Snake 

 Rivers, at least, were wholly free from tnis further drain; tneir propor- 

 tion of escape was demonstrably higher, and their runs should have 

 fared better. In this complicated case, then, not only the natural 

 oscillations in the nms to the different rivers, which might be at any 

 given time in opposite directions, but also the possilnlity of pro- 

 gressive changes m the run of any of them, due to its different historj^ 

 must be contended with. If the Wood River run should for a term 

 of years diminish relatively to the others, its escapement would 

 diminish relatively to the escapement to the other three streams. 



For these reasons, there has not been an attempt to establish a 

 relation between the size of the Wood River escapements and the 

 size of the resulting runs of salmon to the Nushagak with any high 

 degree of expectation. There are too many unknown factors entering 

 into the equation. Only on the assumption that the Wood River 

 run so far overshadows the sum of all the others that the latter ma}^ 

 be considered negligible, is the expectation warranted that close posi- 

 tive results can be achieved. 



It is noted at the outset that the recorded escapement from 1908 

 to 1912 showed an alarming progressive decrease both in actual 

 numbers of fish and in percentage of escape, but the five-year period 

 that follows gives scant evidence of correspondingly decreasecl runs. 

 It is also noted that the largest escapement by far — that of 1908 — 

 was responsible for the four-} ear fish of 1912, and the latter was one 

 of the very poorest runs within the 10-year period under investiga- 

 tion. The 1908 spawning escape was recorded as 1,600,000 fish. 

 The year 1912 had the very- low record of 325,000 to reach the spawn- 

 ing beds, yet it produced the five-year contingent of the nm of 1917, 

 which furnished the largest run of any year since 1908. These are 

 glaring failures, and indicate clearly enough that no such close 

 relation exists between spawning escape on Wood River and the 

 Nushagak run as wall warrant predictions regarding the latter. 



But if search is made for correspondences, which have a high degree 

 of probability in their favor, such can be found. The years 1911 and 

 1912 were jointly responsible for 1916, when the total recorded run 

 was the next to the smallest during the period of 10 years. The 

 escapes both in 1911 and in 1912 were far below the average; in fact, 

 with one exception they were the two poorest recorded escapes in the 

 10-year period. Whatever may be thought of the higher escapes, it 

 looks as though the 325,000 of 1912 and the 354,000 of 1911 were 

 sufficiently below an acceptable minimum to make a decided impres- 

 sion on the total run to Nushagak Bay. The possibility of a chance 

 coincidence can not be eliminated here, and there is no similar case 

 vsdth which to check up. No other instance is recorded in the series 



