In R = In a - b,S + b^X + In S, 



where R was troll catch in year i, S was net gear catch in Cana- 

 dian area 20 during August through September of year ;' - 2, and 

 X was average individual weight of pink salmon caught in the 

 Fraser River in September of year / — 2. The average error of 

 predicted catches from observed catches exceeded ±25% in 

 each area. 



Chinook Salmon 



1. Troll catches were significantly correlated with levels of 

 nominal fishing effort, particularly prior to the opening of 

 the coho salmon season. 



2. Total Washington ocean sport catch was highly associated 

 with the number of angler trips. 



3. Annual troll catch off the central Washington coast was 

 highly correlated with the releases of fall chinook salmon of 

 brood year groups i— 3 and /-4 by lower Columbia River 

 hatcheries. 



4. Canadian troll catches in area 23 during April through May 

 were significantly associated with releases of fall chinook 

 salmon of brood year groups i - 3 and / - 4 by lower Colum- 

 bia River hatcheries. 



5. Annual Washington ocean sport catches were highly cor- 

 related with Columbia River hatchery releases of fall 

 chinook salmon of brood year groups i - 3 and / - 4. 



Levels of Effort. — Troll catches were significantly associated 

 with levels of troll effort, as evidenced by the following correla- 

 tion coefficients. 



Area 



Apr. -May 



June- Aug. 



Sept. -Oct 



Columbia River 



0.894 



0.651 



0.495 



Coastal Washington 



0.791 



0.840 



0.764 



Puget Sound (Wash.) 



0.888 



0.749 



0.696 



Areas C, 21, 23 (Can.) 



0.760 



0.683 



0.727 



Areas 24-27 (Can.) 



0.691 



0.261 



0.623 



The total Washington ocean sport catch was highly correlated 

 with the total number of angler trips during 1964-75 (r = 0.938). 



Indices of brood year abundance. — These were of little 

 predictive value. Troll catch and CPUE in most areas were 

 significantly associated with Columbia River upriver fall 

 escapements (combined for years ;' - 3 and ;' - 4) when data for 

 years prior to 1962 were analyzed separately, but correlations 

 were not significant when data for more recent years were in- 

 cluded. 



Hatcher>' production. — Releases of fall chinook salmon of 

 brood year groups (-3 and i— 4 combined by lower Columbia 

 River hatcheries explained more of the variation in troll catch, 

 troll CPUE, and ocean sport catch than did any other factor. 

 Although trends in fall chinook salmon releases have been 

 similar for all major production areas, we have assumed that the 

 Columbia River plant is the principal factor because numerous 

 tag studies have clearly shown that Columbia River fall chinook 

 salmon predominate in the ocean population. Figure 2 illustrates 

 the relationship between troll catches off central Washington 

 and Columbia River hatchery releases. Figure 3 shows the 

 association between Canadian troll catches in area 23 during 



250-1 



225- 



200- 



I 



o 

 If) 



Q 



z 

 < 

 w 



zy 

 o 



X 



175- 



150- 



125- 



100- 



75- 



50 



0'973 

 O 1974 



O 1971 

 O 1970 



1975 O 



O 1969 



O 1972 



O '963 q |968 



O 1967 

 O '964 Q (966 



O 1965 



r=792 



1 1 1 1 1 1 



200 400 600 800 1000 1200 1400 



1000 POUNDS OF RELEASES 



Figure 2. — Annual commercial troll calch of chinook salmon in (he Coastal 

 Washington area vs. plant of fall brood year groups i— 3 and /-4 combined by 

 lower Columbia River hatcheries, 1963-75. 



I80-, 



160- 



140- 



I 120- 

 tf) 



< 

 if) 



100- 



80- 



60- 



40- 



Ol974 



0'973 

 Ol972 



1975 O 



O 1966 



O 1967 

 I968Q O '969 



O '97, 

 ^1970 



O 1964 



O 1965 

 O 1963 



r=885 



200 



- 1 — 

 600 



400 600 800 1000 



1000 POUNDS OF RELEASES 



- 1 1 



1200 I4O0 



Figure 3. — Canadian commercial troll catch of chinook salmon in areas C, 21, and 

 23 during April through May vs. plant of fall brood year groups / - 3 and / - 4 com- 

 bined by lower Columbia River hatcheries, 1963-75. 



