258 SALMON OF THE KARLUK RIVER, ALASKA 



the spawning grounds during that year. The spawn of the spring escapement, in the 

 opinion of observers, suffered the greatest loss, and it is significant that the return per 

 fish from the spring escapement was only one-third as great as the return per fish from 

 the fall escapement. 



The escapement of 1927 (872,538 fish) produced a moderate-size run and probably 

 would have produced a better run had not the spring run suffered to some extent from 

 unfavorable conditions. Precipitation during the summer of 1927 was in marked 

 contrast to that of 1926. In 1927 the spring spawning population suffered because 

 the streams were at flood stage for a period of time, whereas in 1926 the fish suffered 

 from a lack of sufficient water. 



The escapement of 1928 (1,093,817 fish) produced a fairly good run, and the ratio 

 of return to escapement in both the spring and fall was equal to, or greater than, the 

 ratio of return of 2:1 on which the Alaska fishery regulations are based. 



The escapement of 1929 (900,319 fish) produced a relatively small run. The 

 spring escapement produced a good ratio of return to escapement, but the fall escape- 

 ment produced only a few more fish than were in the escapement for that period. 



Although fluctuations in the ratio of return to escapement were anticipated, 

 it was expected that some correlation would be found between these two factors. 

 The big escapements to the Fraser River (Rounsefell and Kelez, 1938) every fourth 

 year prior to the rock slide in the river in 1913, always resulted in a large run 4 years 

 later. Observations made on the escapement and returns of pink salmon in Puget 

 Sound and Alaska indicate that usually big runs are produced from good escapements 

 and poor or only fair runs produced by poor escapements. The cyclic nature of the 

 catches at Karluk during most of the history of the fishery also indicates that some 

 correlation exists between escapement and return. These and many other instances 

 which might be cited give reason to believe that, normally, a positive correlation exists 

 between escapement and return. 



Figure 3 shows the correlation between the total yearly escapement and the total 

 returns. The most striking point about these data is the utter lack of correlation 

 between the escapements and the returns from the escapements. That such a condi- 

 tion could not have existed during the early days of the fishery is apparent when one 

 considers that for 3 of the 9 years under consideration the ratio of return to escape- 

 ment did not exceed 1.0 to 1.0. Obviously, unless this ratio is greater than 1.0 to 1.0 

 a fishery cannot be sustained. For only one of the years under consideration, 1921, 

 did the return exceed the escapement from which it resulted by an amount approxi- 

 mately equal to the catches made during the early days of the fishery. 



In the consideration of returns from escapements the most important point is the 

 surplus, or return minus escapement, produced by a given escapement. The aim 

 of eveiy regulatory body governing a self-perpetuating biological resource should be 

 to allow the greatest possible catch without endangering future supplies. The size 

 of the population inhabiting a watershed is, in itself, of little concern. For example, 

 if an escapement of 1,000,000 fish always produced a run of 3,000,000 fish, and an 

 escapement of 4,000,000 fish always produced a run of 5,000,000 fish it would be waste- 

 ful to require an escapement of 4,000,000 fish solely on the basis that such an escape- 

 ment produced the largest run. In this hypothetical example the escapement of 

 1,000,000 fish would produce a surplus of 2,000,000, and the escapement of 4,000,000 



