r" M" "I "" l " i 'M i " I III ' M I'l' l I'll I" " I ' II i |" " l "" |i I i'i| " " I " " I i Ti i l ii 1 1| 1 1 

 I 5 10 15 20 25 30 5 10 15 20 25 30 5 10 15 20 25 



JULY 



AUGUST 



30 



SEPTEMBER 



Figure 6.— Seasonal abundance of adult pink salmon in intertidal (main stream) and fresh- 

 water (East and West Forks) areas of Olsen Creek (excluding pools), based on counts 

 made during periodic foot surveys—July through September 1963. 



day before the first observation and one-half 

 day after the last (McNeil, 1964). For the total 

 early run (fresh-water and intertidal runs 

 combined) the mean redd life for 16 females 

 was 8.9 days (range 5-17 days); for the total 

 late run the average for 26 females was 6.2 

 days (range 4-8 days). 



To estimate the total number of spawners 

 (table 4) I divided by 8.9 the total number of 

 fish days (area under the curves in fig. 4) 

 before August 9 (early run) and by 6.2 after 

 August 9 (late run). 



The number of pink salmon in the early 

 r\in in 1963 was nearly the same as in 1961, 

 but the late run was considerably larger in 

 1961 (table 4). Only 34 percent of the total 

 run in Olsen Creek spawned in the intertidal 

 zone in 1963, but 70 percent of the parent 

 run had spawned there in 1961. In all of 

 Prince William Sotind, 46 percent of the pink 

 salmon spawned in the intertidal area in 1963 

 (see footnote 7) and 35 percent in 1963 (see 

 footnote 1). Olsen Creek received 2 percent 

 of the total pink salmon escapement in Prince 

 William Sound in 1961 and 1 percent in 1963 

 (see footnotes 1 and 2). 



Pink salmon appeared on the spawning 

 ground in 1963 about the same time as they 

 had in 1961, and in both years the small early 

 and large late runs spawned throughout the 

 stream (figs. 4 and 6). A drought occurred 

 in September 1963, but it was so near the end 

 of spawning that the resultant low streamflow 

 did not affect the abundance or distribution 

 of the spawners. 



LENGTHS OF FRESH -WATER AND 

 INTERTIDAL SPAWNERS 



Spawning dates and relative numbers in the 

 early and late runs were consistently different 

 between pink salmon that spawned in fresh 

 water and those that spawned in intertidal 

 areas, both in odd and in even years. This 

 relation suggested that the fresh-water and 

 intertidal spawners are discrete populations in 

 the Olsen Bay drainage (Helle et al., 1964). 

 As one test of this hypothesis, I compared 

 the MEHP (mideye to posterior end of hypural 

 plate) lengths of dead spawned-out fish from 

 the various suspected populations. Only 

 spawned-out fish were used because the "home 

 area" could not be determined until the fish 

 had spawned. Elongation of the jaws of males 

 and erosion of the caudal fin of females during 

 spawning precluded use of the more common 

 measurement from mideye to fork of tail. The 

 relation between the two types of lengths was 

 determined also to facilitate comparison of 

 data from Olsen Creek with data from other 

 areas. 



The IvIEHP lengths of carcasses of both 

 sexes were measured with a caliper to the 

 nearest millimeter. Bias in selecting fish 

 was avoided by measuring all of the car- 

 casses within a previously designated section 

 of the stream on each sampling day. Most of 

 the carcasses of the fresh-water spawners 

 accumulated in pools or against logjams close 

 to the spawning riffles and were probably 

 eventually eaten by scavengers, although a few 



12 



