FISHERY BULLETIN: VOL. 85, NO. 3 



PERCENT ERASER SOCKEYE USING NORTHERN PASSAGE 



100 

 90 

 80 

 70 

 60 H 



o 50 



40 



30 



20 



10 







Queen 



Charlotte' 



Sound 



Queen 



<^'t Charlotte . . ^ 

 ^ -^ Strait Johnstone 

 iStrait 



Juan de Fuca  

 Strait 



Salmon 

 Banks 



54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 



YEARS 



plOO 

 -90 

 -80 

 -70 

 -60 



50 o 

 cr 



LlI 



MO ^ 



-30 

 -20 

 10 







Figure l. — Migratory routes of adult sockeye salmon returning to the Fraser River around Vancouver Island. The bar graph 

 indicates the proportion of the total run that was estimated to have used the northern route (data from IPSFC annual reports). 



ing homestream odors. Wickett (1977) extended 

 this hypothesis by using indices of oceanographic 

 processes to indicate the extent of dilute water 

 plumes off Queen Charlotte Sound from 1953 to 

 1976. He concluded that the large proportion of 

 Fraser River water discharged into the ocean 

 northwest of Vancouver Island increased the rate 

 of Fraser sockeye migrating through Johnstone 

 Strait. The assumptions by Favorite (1961) and 

 Wickett (1977) were influenced by the proposal of 

 Hasler and Wisby (1951) that riverine odors 

 learned during sensitive juvenile stages guide the 

 homeward migration of adults in nearshore and 

 river environments (Hasler 1966; Hasler and 

 Scholz 1983). 



We evaluated the extent to which oceano- 

 graphic conditions in offshore waters influence 

 the migratory routes of returning Fraser River 

 sockeye around Vancouver Island. Nine more 

 years of data (1977-85) have become available 

 since Wickett's (1977) publication and four of 



these show unprecedented (57% to 80%) diversion 

 rates via Johnstone Strait. 



COASTAL MIGRATORY PATHWAYS OF 

 FRASER RIVER SOCKEYE 



INPFC Data 



Under the auspices of the International North 

 Pacific Fisheries Commission, Canada, the 

 United States and Japan tagged 99,576 sockeye 

 salmon in the North Pacific Ocean east of long. 

 165°E between 1956 and 1983. Of these, 4,842 

 were recovered, mostly (99.4%) along the coast of 

 British Columbia and Alaska (INPFC 1984). We 

 isolated data on Fraser River sockeye salmon 

 from this larger data set to determine the migra- 

 tory routes of these salmon. In the waters around 

 Vancouver Island, 745 sockeye salmon were re- 

 covered. Since sockeye salmon home accurately 

 (Ricker 1972; Foerster 1968; Quinn 1985), the 



456 



