<^ 0.5 1.0 1.5 2.0 2.5 



FISH IN PARENT ESCAPEMENT (MILLIONS) 



Figure 20. — Relation between proportion of total smolt 

 production migrating at age II and number of sock- 

 eye salmon in pai-ent escapement, Wood system, 1951- 

 59. The number beside each point indicates the par- 

 ent escapement year. 



growing juveniles go to sea as age II smolts — 

 these progeny grew slowly, but most went to sea 

 at age I. The tow net indices of abundance of 

 this year class as yearlings residing in the lake 

 indicated a considerably higher percentage hold- 

 over than was indicated in the index sampling of 

 smolts ; some question exists, therefore, as to the 

 accuracy of the index of abundance of age II 

 smolts in the Wood River. 



Kvichak System 



The lowest recent escapements of sockeye 

 salmon in the Kvichak system (1954 and 1958) 

 produced mostly age I smolts, whereas the inter- 

 mediate escapements (1953, 1955, 1957, 1959) 

 produced mostly age II smolts. More of the prog- 

 eny of the largest escapements (1952, 1956, 

 1960) tended to hold over to age II smolts as the 

 escapement levels increased. The escapement of 

 about 6 million fish in 1952 produced mostly age 



I smolts (or at least only fish of this age returned 

 in large numbers) . The only information we 

 have on the smolt migration in the Kvichak 

 River in 1954 (age I smolts from the 1952 es- 

 capement and age II from 1951) is that local 

 residents in Levelock observed it to be "heavy." 

 The 1956 escapement of 9.4 million produced 46 

 percent age II smolts, and the 1960 escapement 

 of 14.6 million produced at least 78 percent age 



II smolts (fig. 21, table 27). 



80 

 60 

 40 



^ 80 

 < 



Q 60 

 a: 



I 40 



< 



UJ 



<n 20 

 o 



5 



1— 

 < 



i 80 



^ 60 

 j 40 



CO 



12 



14 16 



0.5 



1,0 



20 

 



•59 



1.5 20 



UGASHIK 

 58 MEAN 



2.5 



3.0 



60 



57 



56 



0.5 1,0 1,5 2.0 2.5 3.0 



FISH IN PARENT ESCAPEMENT (MILLIONS) 



Figure 21. — Relation between proportion of progeny mi- 

 grating as age II smolts and number of sockeye salm- 

 on in parent escapement, Kvichak system, 1953-(;u, 

 Naknek system, 1954-60, and Ugashik system, 1958- 

 60. Figure beside each point indicates year of parent 

 escapement. 



Naknek and Ugashik Systems 



Data for the Naknek and Ugashik systems do 

 not indicate that the percentage of sockeye salm- 

 on progeny migrating seaward as age II smolts 

 is correlated with the number of fish in the 

 parent escapement (fig. 21). The escapements 

 in the Naknek system in 1954-58 ranged from 

 0.278 to 1.77 million, but the portion of age II 

 smolts remained nearly constant between 16 and 

 25 percent. 



The amount of growth added in the spring 

 before the juveniles migrate as smolts is influ- 

 enced by climate (Burgner, 1962). In years of 

 favorable growing conditions early in the sea- 

 son, a higher percentage of yearlings may attain 

 some size threshold for migration and leave as 

 age I smolts. Thus, the influence of climate may 

 tend to mask the relation between percentage 

 holdover of progeny in the lakes and the number 

 of parent spawners. 



The major sockeye salmon systems on the east 

 side of Bristol Bay tend to have concurrent fluc- 



SOCKEYE SALMON IN MAJOR RIVER SYSTEMS IN SOUTHWESTERN ALASKA 



447 



