Table 3.— Observed (in parentheses) and estimated catches of marked 1971-brood coho salmon released 

 from the two Columbia River sites and recovered in Pacific coast fisheries, by fishery type and year of 

 capture. 1 Ad-RV = adipose right ventral; Ad-LV = adipose left ventral. 



'Data obtained from: "1973 fin-mark sampling and recovery report for salmon a 

 fisheries" and "1974 Wire tag and fin-mark sampling and recovery report for salmon 

 fisheries," Fish Commission of Oregon, Clackamas, Oreg. 



2 Not sampled. 



3 No sampling for multiple fin-marked coho. 



"Setnet and dip net fisheries. 



nd steelhead from various Pacific Coast 

 and steelhead from various Pacific Coast 



Overall fishery contribution rates for this 

 study are lower than rates reported in studies 

 conducted in the 1960's with coho salmon from 

 Columbia River hatcheries. For all fisheries com- 

 bined, the Youngs Bay release contributed 23.0 

 fish/1,000 released, and the Willard release con- 

 tributed 5.6 fish/1,000 released. In a diet test 

 at Washougal Hatchery (Senn and Noble 1968), 

 the contribution of 1961-brood coho salmon, fed 

 a diet similar to that fed the 1971-brood, was 

 51 fish/1,000 releases to the Pacific coast fisher- 

 ies. Wahle et al. (1974) found the average con- 

 tribution to the fisheries of 1965 and 1966 brood 

 coho salmon was 55 fish/1,000 releases at Colum- 

 bia River hatcheries. Fishery contributions of 

 marked groups of 1967-, 1968-, and 1969-brood 

 coho salmon at Cowlitz Hatchery ranged from 21 

 to 52 fish/1,000 releases. 5 In the earlier 1968- 

 brood study, the Willard Hatchery release con- 

 tributed 7.7 fish/1,000 releases to the Columbia 

 River and Youngs Bay fisheries. We do not know 

 the reasons for the poorer survival of the 1971- 

 brood fish. 



The release site significantly affected fishery 

 contribution despite the low survival. We believe 

 the Youngs Bay release survived at a higher rate 

 than the Willard release fish because the Youngs 



Bay release contributed more heavily to all fish- 

 eries sampled than did the hatchery release. The 

 contribution ratios of the Youngs Bay release to 

 the Willard Hatchery release by fishery are 3.2:1 

 for Washington marine fisheries, 2.8:1 for Ore- 

 gon ocean fisheries, 5.2:1 for California ocean 

 fisheries, 9.4:1 for the Columbia River fisheries, 

 and 4.1:1 overall. Differences between contribu- 

 tion rates when all fisheries are combined are 

 significant (x 2 = 137.36). 



We postulated two possible reasons for the 

 higher fishery contribution of the Youngs Bay 

 release. The Youngs Bay release possibly had a 

 higher survival to the estuary than did the Wil- 

 lard hatchery release because the former group 

 avoided downstream-migration mortalities from 

 predation, gas bubble disease, and from passing 

 over spillways or through turbines at the Bonne- 

 ville Dam. A number of authors have reported 

 the adverse effects of Columbia River dams on 

 survival of juvenile salmonids (Schoeneman et 

 al. 1961; Bell et al. 1967 6 ; Long et al. 1968 7 : Bell 

 and DeLacy 1971 8 ; Ebel et al. 1973; Slatick et al. 



5 Hopley, C. W. 1975. Informal interim report on portions 

 of 1967-, 1968-,and 1969-brood Cowlitz River cohostock timing- 

 evaluation. In Coho marking program on the lower Columbia 

 River. Unpubl. manuscr., p. 9-43. Wash. Dep. Fish., 115 

 Gen. Admin. Bldg.. Olympia, WA 98504. 



6 Bell,M. C, A. C. DeLacy. and G.J. Paulik. 1967. A com- 

 pendium on the success of passage of small fish through tur- 

 bines. Unpubl. manuscr., 268 p. U.S. Armv Corps Eng., 

 Portland Dist., Fish Eng. Res. Program, P.O. Box 2946, Port- 

 land, OR 97208. 



7 Long, C. W., R. F. Krcma, and F. J. Ossiander. 1968. Re- 

 search on fingerling mortality in Kaplan turbines— 1968. 

 Unpubl. manuscr., 7 p. Northwest and Alaska Fish. Cent., 

 Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd. E., Seattle. 

 WA 98112. 



K Bell, M. C, and A. C. DeLacy. 1971. A compendium on 



146 



