GROOT and QUINN: HOMING MIGRATION OF SOCKEYE SALMON 



Table 1 . — Correlations (R) of sea surface temperature at four light- 

 hiouse stations along the British Columbia coast with the percent- 

 age of sockeye salmon returning to the Fraser River via Johnstone 

 Strait during the years 1953-83. 



Lighthouse 

 stations 



tvlarch 



April 



t^ay 



June 



N 



N 



N 



N 



Amphitrite Pt. 0.65 31 0.69 31 0.59 31 0.59 31 



Kains Island 0.65 31 0.65 31 0.65 31 0.63 31 



Cape St. James 0.54 30 0.68 29 0.66 30 0.54 30 



Langara Island 0.55 31 0.62 31 0.65 31 0.64 29 



listed above for the years 1953-85 showed signifi- 

 cant (P < 0.01) positive correlations with 

 nearshore (Kains Island) SSTs, explaining 51% of 

 the variance (Table 2; Fig. 7A). 



Table 2. — Relationship (R and R2) for linear regression analyses of 

 average April-June SST at Kains Island lighthouse, sea level at 

 Tofino, Ekman transport at lat. 50°N, long. 13rW, SST at Station 

 P (50°N, 145°W), and Fraser River discharge at Hope with percent- 

 age sockeye salmon returning to the Fraser River via Johnstone 

 Strait for the years 1 953-85 (N = 33), 1 953-77 (N = 25), and 1 978- 

 85 {N = 8). The level of significance was set at P < 0.01. 



Factors 



1953-85 

 R2 (%) F 



1953-77 



1978-85 



R2 (%) 



R2 (%) 



SST Kains Island 51 0.71* 9 0.30 85 0.92* 



Sea level Tofino 0.19 19 0.44 3.9 0.20 



Ekman transport 4 0.29 4 -0.20 5 0.23 



SST Station P 15 0.39 11 0.33 11 0.33 

 Fraser River 



discharge 2 0.14 45 0.67* 30 -0.55 



•P<0.01. 



YEARS 1953-1985 



< 



IT 



90 



60 



30 - 



® 



• •• • • 



8 8 9 6 10 4 112 12 



TEMPERATURE °C 



KAINS ISLAND 

 TEMPERATURE 

 AV APR -JUNE 



12 8 



YEARS 1953-1977 



2 

 X 

 O 



3 



o 



o 

 o 



V) 



o 



45 n 



30 



® 



3200 



4000 4800 5600 6400 



DISCHARGE mVsec 



YEARS 1978-1985 



FRASER RIVER 

 DISCHARGE 

 AV APR-JUNE 



-21.1 +0,0079x 



=2 = 



R' = 45% 

 N = 25 



7200 



Figure 7. — Relationships between the proportion of 

 Fraser River sockeye salmon migrating via the north- 

 ern route (Johnstone Strait) and A) average sea sur- 

 face temperature and salinity at Kains Island for 

 April, May, and June for the years 1953-85; Bl aver- 

 age Fraser River discharge for April, May, and June 

 for the years 1953-77; C ) average sea surface temper- 

 ature at Kains Island for April, May, and June for the 

 years 1978-85. 



90 



60 



30 



j5 110 115 



TEMPERATURE "C 



12 



KAINS ISLAND 

 TEMPERATURE 

 AV APR-JUNE 



y=-3l7 + 34.0x 

 R^ = 85% 

 N = 8 



12 5 



463 



