UTTER ET AL.: STOCK COMPOSITION OF 1983 CHINOOK SALMON 



Table 5. — Summary of distribution of oceanic coded wire tag recoveries (N) 

 of 1975 brood year fall chinook salmon from the Snake River, and Priest Rapids 

 and Spring Creek hatcheries. 



' Data from L. Gilbreath, Northwest and Alaska Fisheries Center, Seattle WA 981 1 2, pars, 

 commun September 1984 

 ^Data obtained from Pacific Marine Fisheries Commission in 1983. 



in their relative frequencies. In both May and July, 

 the proportion of the Cowlitz-Kalama subgroup 

 (group lb) to the overall tule contribution in the com- 

 mercial fisheries was considerably higher in sam- 

 pling area 2 (average 30%) than in sampling area 

 4 (average 16%). The proportion of this subgroup 

 was highest in the sport fisheries, approaching 

 equality (46%) with the Spring Creek subgroup (la) 

 in the overall data set and predominating in the 

 June-July fisheries (52%). The Spring Creek sub- 

 group strongly predominated in the tule catch of the 

 river fishery of 1 September (84%, Table 3). 



The relative contributions of the three upriver 

 bright subgroups vary considerably in the ocean 

 fisheries (Table 3, Fig. 3). The most notable feature 

 is the absence or negligible contribution of the Priest 

 Rapids subgroup (2b) in all but the last ocean fishery 

 that was sampled, where this subgroup contributes 



a substantial proportion (49%) of the total estimated 

 upriver bright harvest. This finding was unexpected 

 because this subgroup is by far the largest contrib- 

 utor to the overall upriver bright production (Pat- 

 tillo and Mclsaac 1982). The data of the 1 September 

 river fishery are more consistent with expectations, 

 with 83% of the upriver bright catch estimated to 

 be from the Priest Rapids subgroup. The low esti- 

 mated contribution of this subgroup to ocean fish- 

 eries cannot be explained by the large standard 

 deviations accompanying most estimates because 

 the more precise pooled estimates (Table 3) also in- 

 dicate a small Priest Rapids contribution. 



MANAGEMENT CONSIDERATIONS 



The difference in relative proportions of the two 

 tule groups, based largely on class of fishery and 



Commercial 

 troll 



Sport 

 fishery 



^ 



Snake River 

 Priest Rapids 

 Deschutes 



Estimated 



number in 



fishery Catch 



(hundreds) area Date 



7.3 



3.4 



4.3 



5.8 



1-4 



1-2 



1-2 



May 



11.5 1-4 July 



May 28- 

 June 17 



June 18- 

 June 29 



1 ^ Aug 16- 

 '"-^ Sept 11 



I I I I I I I I 1 I r~i I I I I I 1 I I I 



10 20 30 40 50 60 70 80 90 100 

 Percent of upriver bright contribution to fishery 



Figure 3.— Estimated proportions of three upriver bright stocks to different ocean 



fisheries. 



21 



