Table 4. --Concentrations of dissolved substances in intragravel 

 water samples taken from the same 24 randomly selected points 

 in Sashin Creek, August 1962 



u 



About 50-percent saturation at the prevailing stream temperature 

 of 13" C. 



ture and discharge of Sashin Creek in 1962 

 with the previous lO-year average revealed 

 that nearly normal conditions prevailed in 

 1962: 



1952-61 



1962 



Water 

 temperature 



°C. 



13.6 



13.8 



Discharge 



C.f.s. 



60 (range 



15-112 



c.f.s.) 



40 



Based on the rather low levels of dissolved 

 oxygen and the rather high levels of free CO2, 

 high biochemical oxygen demand (B.O.D.) was 

 being satisfied in the Sashin Creek study area 

 during late August 1962. It was not possible 

 to determine the effect of decomposing 1961 

 brood year eggs on the total B.O.D. because 

 water samples were not collected from a 

 suitable control area. The possibility that 

 decaying 1961 brood year eggs materially in- 

 fluenced the total B.O.D. cannot be ignored, 

 however, and the problem warrants further 

 study. 



DISCUSSION AND CONCLUSIONS 



The question of disappearance of salmonid 

 eggs because of decomposition or scavenging 

 has received attention by a few workers. Dead 

 sockeye salmon eggs remained recognizable 

 in a Bristol Bay stream for 1 year (Mathisen, 

 1962). In California, Briggs (1953) placed 

 dead salmon eggs and larvae in permeable 

 containers and burled them in a streambed. 

 Among the test eggs, 1 percent were gone 

 after 30 days, 9 percent after 60 days, and 

 13 percent after 90 days. Test larvae dis- 

 appeared more rapidly than eggs. Gangmark 

 and Broad (1955) placed live Chinook salmon 

 (Oncorhynchus tshawytscha) eggs in permeable 

 containers and buried them in a California 

 stream. They found the number of living and 

 dead eggs and larvae recovered after 45 days 

 to be only 50 percent of the number of live 

 eggs originally buried. In reporting the results 

 of his classic study on survival of salmonid 

 eggs and larvae in New Zealand streams, 

 Hobbs (1937) noted that the disappearance of 

 eggs due to decomposition and physical factors 

 introduced bias to his estimates of mortality; 

 but he felt that scavengers or predators were 

 restricted to the surface gravels and did not 



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