VARIATION AMONG STREAM AREAS IN 

 DENSITY OF FRY 



"When pink s;Union spawnei-s are abundant in 

 Sasliin Creek, tlie ejitire spawning ground is used 

 intensively; but the lai-gest number of fry per 

 s(|uare meter comes usually from the upper area. 

 Tills fact \va,s discovered first for the 1959 brood 

 fry ( Merrell, 1962) , and I observetl a similar differ- 

 ence in subsequent years when spawners were abun- 

 dant. The nuiiil)ers of fry per square meter in the 

 three are^is for 4 brood yeare were as follows (data 

 for the 19.-)9 l)nM)d from Merrell, 1962) : 



Even though the upjier area can potentially 

 produce more fry per unit area than the lower or 

 middle area, observations each year since 19.58 

 show that spawners do not concentrate there. In 

 1965, 14,833 fish (both sexes) spawned at alwut 

 equal density in the upper and middle areas and at 

 somewliat lower density in the lower area (table 

 3). In 1964, when tlie number of spawners was 

 only 2,193, they were concentrated in the lower 

 area, and relatively few were in the upper area 

 (Smedley and McNeil, 1966). In 1963, Sashin 

 Creek had 16,757 spawners, and the number of 

 females jwr square meter was 50 percent greater 

 in the middle area than in the upper or lower area 

 (McNeil, 1966). Only eight pink salmon spawned 

 in -1962; no observations were made on their dis- 

 tribution. In 19(>1, 28,759 spawners were distrib- 

 uted fairly uniformly tliroughout the spawning 

 ground (McNeil, Wells, and Brickell. 19(i4). 

 Because an attempt was made to destroy the run 

 in 1960, no observations were made on distribution 

 of spawners that year. Data from Merrell (1962) 

 indicated tliat in 1959, when 35,391 were present, 

 the numljer of females per square meter in the 

 middle area was at least twice that in tlie lower 

 or upper. Spawners were scarce in 1958 (217), 

 and they concentrated in tlie lower area (Merrell, 

 1962). 



The distribution of spawners in Sashin Creek 

 may depend somewhat on tlie time of spawning. 

 Tagged females in 1963 (table 5 of McNeil, 1966) 

 and 1965 (table 10) "shifted" downstream after 

 tlie midpoint of spawning: early spawners tended 

 to concentrate in the upper and middle areas and 

 hite spawners in the lower area. 



Table 10. — Expecled and observed numbers of early and lale- 

 spawning tagged female pink salmon in three study areas 

 in Sashin Creek, 1965 



(Tagged spawners tliat first occupied the spawning ground by August 31 

 were designated as "early"; tagged spawners that occupied the spawning 

 ground September 1 and later were designated as"late"] 



l!(2d.f.) =9.27 (P. 0.01). 



In an earlier paper (McNeil, 1966) I att'-ibuted 

 tlie downstream sliift from the upper area in 19(;3 

 to turbulent water caused by heavy rainfall in 

 the latter half of tlie period of spawning (4.5 cm. 

 per day average from September .3 to 29, 1963) ; 

 but in 1965, rainfall in September averaged less 

 tiian 0.2 cm. ])er day, and tiie streamflow remained 

 low throughout tlie latter lialf of the jjcriod of 

 s])a\vniiig — a (■oiulition oppositi^ to 19()3. 



It now :i|)pears that late spawners are less 

 inclined to occupy upstream spawning beds of 

 Sashin Creek than are the early spawners, regard- 

 less of waterflow. My earlier interpretation of the 

 cause of the downstream sliift of tlie late spawnei-s 

 now appears to be incorrect. 



RELATION OF WATER QUALITY TO 

 SURVIVAL AND DEVELOPMENT OF 

 EGGS AND ALEVINS 



Tlie concentration of dissolved oxygen in intra- 

 gravel water in August and Sei)teinlier 1965 

 heli)eil coiiiirin earlier conclusions (McNeil, 

 19(;(;) that the environment is more favorable for 

 eggs in the upper area than in the middle or lower 

 area. Samples of intragravel water, collected from 

 random points within each area .\ugust 16 and 

 31 and September 13 and 22, were analyzed for 

 dissolved oxygen (table 11). 



.-jS2 



KISH .\M) \V1I,I)I-I1''K sEinici-: 



