existing literature on size of juvenile sockeye salmon. 

 When sampling was not done on or after 1 September 

 or the apparent growth was negative or otherwise 

 anomalous, the length on 1 September was estimated 

 as follows: for age fish, the increase in length in 

 Coville Lake and for age I fish, the increase in length 

 in Iliuk Arm between the last date of sampling in the 

 lake in question and 1 September was added to the 

 calculated size on the last date of acceptable sampling 

 in the lake in question. 



Coville Lake and Coville River. — Curves depicting 

 the apparent growth of age sockeye salmon collected 

 in tow nets in Coville Lake and in fyke nets in Coville 

 River are presented by area for 1961-64 in Figure 11. 

 In general, average lengths increased rapidly from 

 early July to mid-August (days 3 1 to 80) and somewhat 

 slower thereafter. The decrease in rate is most appar- 

 ent in 1963 and 1964 when more areas were sampled at 

 shorter intervals. The average size of the emigrants in 

 Coville River was clearly greater than that of the 

 juveniles taken in tow nets in the area adjacent to the 



river— C-2L in 1963 and C-5 in 1964. There was little 

 difference among the other four areas (C-l to C-4) in 

 1964. 



The length frequency distributions of the juvenile 

 sockeye salmon from Coville Lake and Coville River 

 in 1961-64 are presented in Figures 12 and 13. The 

 frequencies are generally unimodal and the observed 

 differences in average length (Table 21) are due to the 

 greater abundance of larger sizes rather than to differ- 

 ences in ranges in lengths in the samples. 



The greater average lengths of age sockeye salmon 

 in the lakes of the Naknek system on 1 September 

 1962 (Table 21) than in the other years was true for fish 

 from Coville Lake, but not for those from Coville 

 River. No explanation is offered for the lack of a larger 

 average size for fish in Coville River. 



Age I and older fish were rare in catches from tow 

 nets in Coville Lake and fyke nets in Coville River 

 during the summer. These older fish appear in the 

 length frequencies in sufficient numbers to cause a 

 bimodal curve in the samples from tow net catches 

 only in early July 1964 (Fig. 13). 



I ' I ' I ' I ' I ' I ' I M ' I i I i I i I ' 



436JH • C-l T04, JULY 16-17, 

 N=l,256 

 ° C-5. JULY 16 , N=679 



I i I ' I U i I ' I ' I ' I ' I ' I I I i I I 



• C-l T04, AUG 2-3 



N=737 

 o C-5. AUG. 4 



N = 62l 

 . COVILLE RIVER 



AUG 4 



N=277 



C-l TO 4, SEPT 2-5 

 N = I26 



C-5, SEPT. 2 

 N = 27 



. COVILLE RIVER 

 SEPT 1-5 

 N = 27l 



1 I ' I I I I | 



I ' I ' I ' I ' 



' I ' I l 1 I I I I ' I ' I U I I I I ' I I I I 

 30 42 54 66 78 90 30 



1964 



FORK LENGTH (MM ) 



I I ' I M ' I ' | I I I I I I I 



42 54 66 78 90 



1964 



Figure 13. — Length frequency distributions of juvenile sockeye salmon (age and age I 

 combined) captured in tow nets in sampling units of Coville Lake and in fyke nets in 

 Coville River for several time periods between July and September 1964. (See Figs. 1 and 

 2 for designations of sampling units.) 



35 



