bedrock. The main spawning ground-- 

 13,629 m.^--lies between the intertidal zone 

 and the canyon. This study considered a 

 13,084 nn.^ area, which was divided into three 

 areas--upper {Z,945 m.^), middle (4,067 m,^), 

 and lower (6,072 m.^). The upper area has a 

 relatively steep gradient and coarse mate- 

 rials in the bed; the middle area has an inter- 

 nnediate gradient and medium-sized materials; 

 and the lower area has a shallow gradient 

 and fine materials (table 1). 



Table 1. — Size conposition of bottom 



materials-'- and average gradient in three 

 areas in Sashin Creek 



Procedures for sampling bed materials to 

 measure size conposition are described by 

 NbNeil and Ahnell (1964). Materials >15.2 mm. 

 diameter are excluded. 



^ Cobbles are > 12.7 mm. diameter. 



Pebbles and granules are 1.68 to 12.7 mm. 

 diameter. 



^ Sands and silts are < 1.68 mm. diameter. 



NUMBER, DENSITY, AND DISTRIBUTION 

 OF SPAWNERS 



Distribution and density of female spawners 

 were studied to provide answers to three 

 questions: (1) Does the density of females 

 differ among the three study areas? (2) Are 

 any differences in distribution of females 

 related to size of the spawners? (3) Are any 

 differences in distribution of females related 

 to tinne of spawning? The observations were 

 limited to females because potential egg depo- 

 sition is determined by the number and aver- 

 age egg content of females. Other observations 

 at Sashin Creek (unpublished) have established 

 that a female remains in the vicinity of her 

 redd fronn beginning of spawning to death. 



Adult male and female salmon were counted 

 as they entered the Sashin Creek weir at the 

 head of tidewater. ■"■ The first salmon was 

 counted August 10 and the last September 6. 



One hundred females were tagged August 20 

 and 21. (It was later found that 30 percent of 



the total females had passed the weir by 

 August 21 and that 10 percent of the total 

 had occupied the spawning ground.) A Petersen 

 plastic disk, 5/8-inch diameter, was attached 

 to each female on each side of the origin 

 of the dorsal fin. Disks of different colors 

 were used to identify females longer or 

 shorter than average. The average mideye- 

 fork length--49.9 cm. --was determined from 

 measurennents of 50 females. Fifty females 

 longer than average were tagged with pink 

 disks, and 50 shorter than average with 

 green disks. Females 49.9 cm. long were 

 not tagged. 



The females (tagged and untagged) were 

 counted in the three study areas by ob- 

 servers on foot who made surveys on the 

 following weekly schedule: observer A2-- 

 Monday and Thursday; observer B--Tuesday 

 and Friday; and observer C-- Wednesday and 

 Saturday. The location of each tagged female 

 was determined during each survey and plotted 

 on a detailed map of Sashin Creek. 



The total number of females spawning in 

 each area was estimated by the following 

 formula: 



Number spawning = 



X Dally number on spawning ground 

 Average redd life 



Daily nunnbers were sunnnned by fitting a 

 curve to the number of females counted each 

 date surveys were made and measuring the 

 area under the curve (the area under the 

 curve is given as female-days). Average 

 redd life (the estimated number of days 

 each female spent on the spawning ground) 

 was determined from the daily observations 

 of tagged females. The method has been 

 further illustrated by McNeil (1964a and 

 1964b). 



Number and Density of Spawners 



Agreement was good between the estimates 

 of spawning females based on counts during 

 the surveys on foot (9,030) and the counts at 

 the weir (8,740). The estimate for the sur- 

 veys was the average of the following counts 

 by the observers: A, 9,640; B, 7,510; and 

 C, 9,950. 



Agreement among the observers on the 

 estimates of relative densities of spawners 

 in the study areas also was good. 3 The density 

 was about 50 percent higher in the middle 

 area than in the upper and lower areas 

 (table 2). 



■"- Males and females can be separated easily by well- 

 developed secondary sexual characteristics (Davidson, 

 Vaughan, Hutchinson, and Pritchard, 1943). 



2 Two persons made observations on Monday and Thurs- 

 day--the first through September 16 and the second after 

 September 16. 



^ Density was estimated by dividing the square meters 

 of spawning ground into the estimated number of females 

 spawning. 



