FISHERY BULLETIN: VOL. 80, NO. 4 



pink salmon fry abundance would be low than 

 those in 1966 and 1968 when pink salmon fry 

 would be abundant. When chum and pink salmon 

 fry migrated at similar times, chum salmon 

 fry-to-adult survival was lower than when chum 

 salmon fry migrated earlier than pink salmon 

 fry. Pink salmon grow faster than do chum salm- 

 on (Ricker 1964), and this faster growth rate 

 may allow them to outcompete chum salmon fry 

 for food. The influence of pink salmon on egg-to- 

 fry survival of chum salmon was not examined, 

 but we expect it would be minimal relative to en- 

 vironmental influences as pink salmon spawn 

 earlier in the Fraser River than do chum salmon. 

 The present study suggests some areas that 

 need to be explored further. Interspecific inter- 

 actions between pink and chum salmon fry may 

 be investigated by marking and varying the size 

 and time of release of chum salmon fry in years 

 when pink salmon fry are present and measuring 

 rates of adult returns for these sets of fry, similar 

 to the studies of Fraser et al. (1978) for chum on 

 the Big Qualicum River and Bilton (1978) for 

 coho salmon, Oncorhynchus kisutch. 



ACKNOWLEDGMENTS 



We are indebted to those who sampled and 

 aged the salmon caught in the test fishery and 

 sampled the fry during their downstream migra- 

 tions. Tom Bilton provided the data used to con- 

 vert chum fork lengths to postorbital-hypural 

 length. M. C. Healey and B. E. Riddell made 

 many helpful suggestions which improved the 

 manuscript. The manuscript was prepared with 

 the assistance of the staff at the Pacific Biologi- 

 cal Station. 



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