Table 9 Pink salmon egg densities in interticial gravel at Olsen Bay approximately 2 weeks 



after spawning season (90-percent confidence intervals to the nearest digit) 



3- to 4-foot stratum, however, egg densities of 

 21 per square foot in 1 960 and 31 per square foot 

 in 1961 were only about one -tenth the densities 

 in the upper strata. The stream bottom at the 3- 

 to 4-foot stratum was covered by tidewater ap- 

 proximately 83 percent of the time (fig. 2). 

 Spawning activity ceased and was replaced by a 

 milling about of adults while tides covered the 

 spawning areas. This periodic interruption of 

 spawning activity probably explains in part the 

 low egg densities in the 3- to 4-foot stratum. 



The greater total egg cieposition in 1961 did 

 not result in higher live egg densities. Live egg 

 densities rsinged from 10 to 1 36 per square foot 

 in 1960 and from 7 to 136 per square foot in 

 1961 (table 9). 



The lower percentage of live eggs in 1960 at 

 the 3- to 4-foot stratum (48 percent compared 

 with 83 and 90 percent in the upper strata (table 



9)), was indicative C)f poor survival from ad- 

 verse environmental conditions at the lower 

 tide level. 



Survival Over Winter 



Survival over winter was estimated by conn- 

 paring live fry densities in the spring of 1961 

 with live egg densities the previous fall. No 

 pink salmon fry were seen in the estuary in 

 March 1961, and it was assumed that few if 

 any fry had emerged before the 1961 spring 

 sampling between March 23 and 29. 



No fry or dead eggs were found in the 3- to 

 4-foot stratuna'; 35 live fry per square foot 

 were found in the 7- to 9-foot stratum; and 73 

 fry per square foot were found in the 10- to 

 11 -foot stratum (table 10). Only a few dead 

 eggs were dug fronrx the upper two strata. 



Table 10. Pink salmon egg and fry densities in intertidal gravel at Olsen Creek, March 23-29, 



(90-percent confidence intervals) 



22 



