Table 6. --Estimated pink and chum salmon fry migrations from certain strata. 



Prince William Sound, 1957 



DISCUSSION AND CONCLUSIONS 



The pink and chum salmon fry enumeration 

 program in Prince William Sound in 1957 

 showed clearly that the amount of sampling 

 required to obtain precise estimates of the 

 total seaward migration of fry would be very 

 expensive. It became apparent that traps were 

 not entirely satisfactory for estimating fry 

 abundance. The prolonged migration and the 

 need for attending the traps day and night 

 required that each study stream be manned 

 continuously over a 3-month period. Further- 

 more, vulnerability to high tides and unusual 

 streamflows required that traps be fished 

 upstream from most intertidal areas where a 

 large proportion of pink salmon spawn. Preda- 

 tors such as Dolly Varden trout and sculpins 

 introduced unknown errors by entering the 

 traps and devouringlargenumbersof fry. Also, 

 the 1957 studies revealed the need for study- 

 ing the behavior of fry in relation to the 

 traps. 



Estimates of pre-emergent fry abundance 

 in intertidal areas are considered by the 

 authors to be gross and to have limited use- 

 fulness because of the exploratory nature of 

 the 1957 work. The excavation of sample 

 quadrats with shovels and forks proved to be 

 inefficient. For a more efficient sampling 

 program, fry digging should be accomplished 

 before fry begin to emerge so as to include 



all of the fry population in the sampling pro- 

 gram. Extent of adult intertidal spawning can 

 be determined for each study stream in the 

 fall, thereby limiting the area to be sampled. 

 Variability in fry abundance and the distribu- 

 tion of fry in stream gravels should be con- 

 sidered in determining the number and loca- 

 tion of samples required for estimating fry 

 abundance. The 1957 data provide a basis 

 for future fry sampling studies. 



It was not possible to estimate the total fry 

 migration from Prince William Sound streams 

 in 1957 with confidence limits because of 

 limitations in the sampling program. Much 

 was learned, however, about the duration and 

 character of the fry migration in several 

 types of streams and the extent of intertidal 

 spawning was more fully appreciated. 



SUMMARY 



1. Pink and chum salmon fry trapping was 

 initiated in Prince William Sound streams in 

 1957 to provide a basis for predicting the size 

 of subsequent adult runs and to provide a 

 measure of the survival of young salmon in 

 fresh water. 



The objectives of the 1957 work were (1) 

 develop sampling methods for estimating the 

 abundance of fry in the stream proper and in 



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