Table 5. — Expected and observed numbers of 

 early- and late-spawning female pink salmon 

 in three areas in Sashin Creek 



[X2(2 d.f.) = 7.87 (probability = 0.02)] 



females the downstream area. The downstream 

 "shift" in distribution of tagged females during 

 September was not related to date of entry 

 into the stream because all tagged females 

 entered Sashin Creek on August 20 and 21. 

 The shift may have been caused by unusual 

 weather in 1963. 



The weather was exceptionally dry before 

 September 3 (average daily rainfall, August 10- 

 Septenaber 2, 0.25 cm.) and exceptionally wet 

 thereafter (daily average, September 3-29, 

 4.52 cm.). The early period was the third 

 driest and the late period the wettest in 26 

 years of record. 



DENSITY, DISTRIBUTION AND SURVIVAL 

 OF EGGS, ALEVINS, AND FRY 



Eggs and alevins were sampled periodically 

 within the three study areas, and fry nnigrating 

 to sea w^ere counted at a weir at the head 

 of tidewater. Eggs were collected after spawn- 

 ing (late September); and eggs and alevins 

 were collected during hatching (mid- 

 December), before emergence (late March), 

 and during emergence (early and late May). 

 All eggs collected in March and May were 

 dead. The sampling locations, each repre- 

 senting 0.1 m.2 of the streambed, were se- 

 lected at random within the study areas with 

 the aid of tables of random numbers. Hydraulic 

 sampling equipment used for collecting eggs 

 and alevins was described by McNeil (1964b). 

 The downstream migration of fry started 

 in late March and lasted until early June. 



Density and Distribution of Deposited Fggs 



The number of eggs recruited to a spawning 

 bed approaches an upper limit as the density 

 of spawners increases and the percentage 

 of potential egg deposition recruited to the 

 spawning bed decreases (McNeil, 1964a). The 

 present study indicated that the percentage 

 of potential egg deposition recruited to the 

 spawning bed is also related to the size of 



materials in the spawning bed. On the basis 

 of the density of spawners, the density of 

 eggs at the end of spawning should have 

 been highest in the nniddle spawning area 

 but actually was highest in the upper area 

 (the area with coarse bottom materials and 

 steep gradient). Furthermore, the estimated 

 potential egg deposition was equal in the 

 upper and lower areas, but at the end of 

 spawning the number of eggs per square 

 meter was twice as great in the upper area 

 as in the lower (table 6). 



Other evidence indicates that the percentage 

 of the spawning ground used for egg deposi- 

 tion depends on the density of spawners and 

 is independent of the size of materials in 

 the spawning bed. To index the percentage 

 of area used by spawners, I combined sam- 

 pling units (0.1 m.^) where more than three 

 eggs were collected at the end of spawning; 

 units that had three or fewer eggs per 0.1 m.2 

 were considered to be unused. My selec- 

 tion of more than three eggs per 0.1 m. ^ to 

 index use is arbitrary, but some small value 

 greater than zero is required to help correct 

 for eggs that drift to points not used by 

 spawners. A test of hypothesis that more 

 than three eggs per sample would be ob- 

 tained with equal frequency among the three 

 study areas yielded a value X 2 (2 d.f.) = 

 14.1 (probability = 0.001). The percentage of 

 samples that contained more than three eggs 

 was highest for the nniddle area (table 7)-- 

 the same area that had the highest density 

 of spawners. 



The percentage of the spawning ground 

 used for egg deposition appeared to be re- 

 lated to the average density of spawners; 

 but the efficiency of egg deposition was re- 

 lated to both the size composition of mate- 

 rials in the spawning bed and the average 

 density of spawners. Under conditions of 

 streamflow prevailing in 1963, the rela- 

 tively coarse materials in the upper area 

 provided for more efficient recruitment of 



Table 6. — Potential and observed density of 

 eggs of pink salmon in three areas in 

 Sashin Creek at the end of spawning 



