This paper compares scale samples 

 collected both in the trunk river and on 

 spawning grounds in the Kvichak River 

 system during the 1956 to 1958 field 

 seasons. Because resorption erodes much 

 of the peripheral part of scales of fish on 

 the spawning ground, leaving only the 

 central portion legible, comparison is 

 confined to freshwater age composition. 



SAMPLING AREAS 



Kvichak River 



The trunk river of the Kvichak system 

 is the Kvichak River. In their upstream 

 migration, red salmon follow the banks 

 of this river and pass steadily into the 

 lake along both sides of the outlet. They 

 seldom use the deep midstream section 

 as a migratory route. Escapement can 

 therefore be sampled from either shore in 

 the river or at the lower end of Lake 

 niamna (fig. 1). 



Samples of Kvichak River escapement 

 were taken at Igiugig (1),' which is situated 

 on the upper reaches of the river. Owing 

 to the topography of the bottom and wave 

 action caused by a prevailing wind, most 

 sampling took place on the left or south- 

 eastern shore in Lake Iliamna immediately 

 above the outlet. 



Spawning Grounds 



There are three principal types of 

 spawning habitat in the Iliamna-Clark 

 system. First in importance are the 

 tributary streams and rivers, which sup- 

 port about 70 percent of the visible 

 spawning population. Next in importance 

 are the beaches on Lakes Iliamna and 

 Clark and on the accessory lakes tributary 

 to thenn. Last are the spring-fed ponds, 

 such as Hudson Ponds (6), in which only a 

 few salmon spawn. 



All fish do not appear on the various 

 spawning grounds at the same time nor 

 within a short period of time. Although 

 the entire escapement has passed through 

 Igiugig and entered Lake Iliamna by the 

 end of July, some populations do not 

 appear on the spawning grounds until 

 October or later. While attempts were 



2 The Arabic figure in parenthesis immediately following the 

 locality is the number used in figure 1. 



made to obtain measurements and scale 

 samples from all known important spawn- 

 ing areas in the system, it was indeed a 

 formidable task to effect such a compre- 

 hensive coverage over a wide area and 

 for an extended period of spawning. 



SAMPLING METHODS 



Kvichak River Sampling 



The escapement on the Kvichak River 

 was sampled with a beach seine of 

 cotton webbing with 3 -inch mesh (stretch 

 measure). The net was 200 feet long and 

 12 feet deep and was set with a skiff 

 powered by an outboard motor and hauled 

 in manually. 



The escapement past Igiugig usually 

 extends over the month of July. Except 

 for the first and last few days of the 

 migration, when only a few fish were 

 running, fish were sampled daily. Each 

 day 3 or 4 hauls were made, which 

 normally took 4 to 6 hours. Fish were 

 measured and tagged, and a scale was 

 removed from each fish before it was 

 released. When possible, 40 or more 

 scale samples, about half of them from 

 each sex, were collected each day. 



Seining was carried on during a period 

 of about 3 weeks each season. During 

 this period, 87 to 99 percent of the 

 escapement made its way into the lake, 

 as revealed by daily counts (table 1). 



Spawning Ground Sampling 



Individual spawning grounds were sur- 

 veyed by air, whenever possible, at a 

 time when the greatest number of fish 

 was present. A visual estimate of the 

 population was taken then, but the actual 

 sampling was deferred until later when 

 enough dead fish for an adequate sample 

 were available along the banks. At that 

 time, a ground survey was made to take 

 the sample. 



The total spawning population seen dur- 

 ing our aerial surveys constitutes only a 

 fraction of the population counted at 

 Igiugig. In the 3 years, 1956 to 1958, 

 this fraction ranged from 10 to 18 per- 

 cent. This relatively low estimate of the 

 spawning population is partly due to the 

 numbers of fish seen represent only the 



