carcasses. On surveys in brushy areas, 

 whistles were blown every few minutes to 

 alert the bears; if they heard our approach the 

 bears usually avoided us. Polaroid glasses 

 were used to insure maximum and comparable 

 visibility for all surveys. In addition to sur- 

 veys on foot, three surveys were made from 

 the air. Table 3 summarizes the sightings made 

 on surveys. Of the aerial surveys, only the 

 one on Headwater Creek was used to estimate 

 numbers of fish. 



Although tagging 2 percent of the fish passing 

 the weir should have resulted in a 1:50 ratio 

 of tagged to untagged fish in the population 

 above the weir, the number of tagged fish in 

 samples was always less than expected. Five 

 possible explanations for this discrepancy 

 are: 



1. Tagged fish suffered a heavier mor- 

 tality than untagged fish. This can be dismissed 

 because there was no evidence of tagged fish 

 dying before spawning. 



2. Tagged fish behaved differently from 

 untagged fish, resulting in biased samples. 

 This is not likely since there was never any 

 evidence of high concentrations of tagged fish 

 in locations where schools were visible. A 

 tagging experiment on Hidden Creek in 1949 

 further substantiated this conclusion (Eicher, 

 1951). 



3. Calculations for each day's tagging 

 were incorrectly made. On the basis of the 

 observed count, this was not a factor. Each 

 day's tagging, based on the previous day's 



TABLE 3. — Summary of sockeye salmon sighted and fin clipped by observers on 

 stream and aerial surveys. Brooks Lake system, July 26 to September 28, 1957 



Location 

 and number 

 of surveys 



Live 

 fish 



Total tags 

 recovered 

 from dead 

 fish 



Total tags 



seen on 

 live fish 



Number 



Up- a- tree Greek 



5 518 



One Shot Creek 



4 559 



Hidden Creek 



4 923 

 Headwater Creek 



5 1 4,500 



West Creek 



1 

 Brooks Lake 

 beach 

 3 



Total 



Brooks River 

 3 







Number 







1 



2 



17 

 



Number 



6 



7 

 15 

 55 







Grand total 6,857 3,378 



41 



30 



83 



■"" Aerial survey estimate. 



