ABUNDANCE AND AGK OF KVICHAK RIVER RED SALMON SMOLTS 



311 



Table 9. — Comparative hunrly catches of synoltf! at index 

 site and at site B,, June 7-10, 1955 



tends to average out over a period of time, in- 

 dicatinj? that nets fished in the general index 

 area should sample effectively. 



Smolt Catches at Distant Net Sites 



In 1957 and 1958, efforts were made during 

 most of the season to estimate the variability 

 in smolt catches by fishing the index site simul- 

 taneously with site C, which is located 2 miles 

 upstream (fig. 12). The daily smolt catches of 



40- 



20 



1957 



— I — 

 21 



-^^ 



31 



10 



20 



30 



Index site 



Site C 



FiCJURE 12. — Comparative smolt catches at index site and 

 site C, Kvichak River, 1957 and 1958. 



the two nets for 1957 were similar, as were the 

 total catches. The total catch at the index site 

 was 23,000 fish and at site C, 19,000 fish (ap- 

 pendix table 13). These comparable catches 

 suggest that both nets were fishing the same 

 population at about the same rate during this 

 year of relatively small abundance. In 1958, a 

 year of much greater smolt abundance, the daily 

 catches of the same two nets simultaneously re- 

 flected the fluctuations in the smolt migration 

 but with less fidelity than in 1957 (fig. 12; ap- 

 pendix table 14). The total catch at site C in 

 1958 was only 40 percent as large as the catch 

 at the index site. The diflFerence in total num- 

 bers was due to much greater catches at the 

 index site on the 5 days of heaviest migration. 

 Visual observations and actual catches during 

 these 5 days indicated that a large proportion of 

 the smolt migration pas.sed the upriver site C 

 before the net-setting time. 



AGE COMPOSITION OF SMOLTS 



For simplicity of analysis, samples used in 

 smolt age determinations were restricted to 

 those collected on days of major catches. The 

 percentage of each year's smolt catch repre- 

 sented by the samples is shown in table 10. 



Age analysis has been directed toward identi- 

 fication of two smolt groups only : fish which 

 have spent one winter in fresh water, and fish 

 which have spent two winters in fresh water. 

 According to scale samples collected since 1955, 

 smolts that have spent three winters in fresh 

 water and fry (no winters) have been rare. 

 Their rarity has been further verified by 

 analysis of about 6,500 adult red salmon scales 

 that were taken from escapement samplings at 

 the outlet of Iliamna Lake from 1955 to 1959. 



Table 10. — Smolt age-determination saynples from the 

 Kvichak River 



1 The samples were taken at both site A and the index site: there- 

 fore, the actual catches of these two sites, Hiirinvr nijfhts of samplinc 

 were added to obtain the SI, 000. 



