30 10 50 60 70 80 90 

 DAYS SINCE MAY 31 



30 40 50 60 70 60 90 



Figure 19. — Curves of apparent growth of age sockeye salmon captured in tow nets in 

 sampling units of South Bay 1961-63. 



Arm — a decrease in growth rate and average length 

 appears in the South Bay data. The apparent negative 

 growth of age I fish in South Bay may be due to the 

 combining of data to produce a single curve. On the 

 other hand, it may be due to the loss of larger fish to 

 the summer migration of smolts in the Naknek River. 

 If this summer migration of smolts did not involve fish 

 from Iliuk Arm, the observed difference in growth 

 curves of South Bay and Iliuk Arm would result. 



The length frequency diagrams of juvenile sockeye 

 salmon from South Bay (Fig. 21) resemble those from 

 Iliuk Arm. In general, there is a bimodality indicating 

 two age groups (age and age I). In those periods 

 when all three sampling units of South Bay were sam- 

 pled, the curve for age I fish from unit 6 (the most 

 downsystem area) was to the right of those of the other 

 two units — larger age I fish were relatively more 

 abundant in the downsystem portion of South Bay. 

 Age I and older sockeye salmon in South Bay were 

 similar in length to those in Iliuk Arm (Table 21). 



West End. — Apparent growth curves for sockeye 

 salmon in the West End are available only for age 

 fish and only in 1962 and 1963 (Fig. 22). The growth of 

 age fish from West End differed from that in Iliuk 

 Arm and South Bay in that the growth in West End 



fish tended to decrease during the summer. The aver- 

 age lengths of age fish were, however, usually grea- 

 ter in samples from West End than in those from other 

 lakes of the system on the same date (Table 21). Al- 

 though the samples were small, within West End the 

 average lengths were generally greatest in N-4, the 

 area adjacent to South Bay. The average lengths (in 

 millimeters) of age sockeye salmon in samples from 

 N-4, N-2, and N-l were as follows: 



Date 



20 August 1962 

 31 August 1963 

 3 September 1964 



Age I and older sockeye salmon were too scarce in 

 tow net catches from West End to permit construction 

 of growth curves. The average length of this group 

 was greater here than in Iliuk Arm or South Bay. 



The length frequency graphs for samples of juvenile 

 sockeye salmon from West End (Fig. 23) are unimodal 

 because of relatively few age I fish in the tow net 

 catches. 



'"No sample taken. 



30 40 50 60 70 



90 30 40 50 60 70 60 90 30 40 50 60 70 80 90 

 DAYS SINCE MAY 31 



Figure 20. — Curves of apparent growth of age I sockeye salmon captured in tow nets in 

 sampling units of South Bay 1961-63. 



39 



