FISHERY BULLETIN: VOL. 72. NO. 1 



2 and Table 3). During 1968 and 1969, there was 

 no sampling done in the southeast Alaska troll 

 and gill net fisheries. During the 3 yr of mark 

 sampling, an average of 15.4% of the coho catch 

 was examined for marks (Table 4). A total of 

 37,632 marked coho was recovered from 1967 

 through 1969 (Tables 5a and 5b). 



The appropriateness of the estimating pro- 

 cedures used to determine hatchery contribution 

 is dependent on the validity of six assumptions. 

 Additional studies and data collections previous- 

 ly described were incorporated into the marking 

 experiment to help test the assumptions. The 

 first assumption, permanence of fin marks, was 

 tested by holding marked fish in fresh water 

 over a period of months. Little total regeneration 

 occurred, but maxillary regeneration caused con- 

 fusion between maxillary-adipose and adipose- 

 only marked coho salmon. The second assump- 

 tion, origin offish marked with hatchery marks, 

 was tested by examining returning adult coho 

 prior to the marking study and coho fingerlings 

 at the time of marking for natural marks. No 

 noteworthy numbers of naturally missing adi- 

 pose fins or maxillary bones were observed. 

 Prior to this study, a number of age studies have 

 supported that Assumption 3, all adult coho are 

 3 yr old, is valid (Godfrey, 1965). The mark 

 sampling data (Appendix Tables 2a and 2b) in- 

 dicate that the fourth assumption, same maturi- 

 ty schedule for marked and unmarked fish, is 

 valid. Appendix Tables la and lb show the 

 validity of Assumption 5, hatcheries in a given 

 section have the same proportion of marked 

 releases. Assumption 6, equality of ocean dis- 

 tribution could not be tested because regenera- 

 tion and nondetection of maxillary marks dis- 

 torted the picture. 



A total of 179,096 marked 1965- and 1966- 

 brood coho salmon were estimated to have been 

 caught. An additional 33,910 marked coho 

 returned to study hatcheries to spawn (Tables 

 6a and 6b). The theoretical estimated catch 

 assuming no marking had taken place was 

 2,188,172 coho and comprised about 16.1% of 

 the total catch of 1965-66 brood coho in the fish- 

 eries sampled (Table 7). 



The estimated costs of rearing the 1965 and 

 1966 broods of coho salmon are $1,292,300 and 

 $1,226,600, respectively. The estimated benefits, 

 including carcass sales, received from the har- 

 vest of these two broods of coho are $8,583,625 



158 



and $9,106,552, respectively. The benefit to cost 

 ratios are then 6.6 to 1 for the 1965 brood and 

 7.4 to 1 for the 1966 brood. 



ACKNOWLEDGMENTS 



Many agencies and individuals assisted in 

 planning and implementing the hatchery evalu- 

 ation study. The Canadian Government financed 

 and conducted a program of mark sampling in 

 the British Columbia fisheries. The State agen- 

 cies provided research and management per- 

 sonnel and necessary catch data. Donald D. 

 Worlund, National Marine Fisheries Service, 

 developed the design of this study and was the 

 primary mathematical consultant. Jack 

 Richards, National Marine Fisheries Service, 

 developed the justification for the sport and com- 

 mercial economic evaluation. Robert C. Lewis, 

 Fish Commission of Oregon, improved the 

 method of amortizing hatchery construction 

 costs. Harold Godfrey, Fisheries Research Board 

 of Canada; Gary Finger, Alaska Department of 

 Fish and Game; Emanual A. LeMier, Samuel G. 

 Wright, and Harry Senn, Washington Depart- 

 ment of Fisheries; Fred E. Locke, Oregon 

 Game Commission; Ernest R. Jeffries, Earl F. 

 Pulford, and Roy E. Sams, Fish Commission of 

 Oregon; Paul T. Jensen, L. B. Boydstun, and 

 William H. Sholes, California Fish and Game 

 Department; Harlan E. Johnson and Warner G. 

 Taylor, Bureau of Sport Fisheries and Wildlife; 

 Arthur H. Arp, Dean A. Eggert, Steven K. 01- 

 hausen, William D. Parente, Joe H. Rose, and 

 Paul D. Zimmer, National Marine Fisheries 

 Service; and many members of their respective 

 agencies gave their time and effort. Helpful edi- 

 torial comments were contributed by Frederick 

 Cleaver, George M. Kaydas, Richard T. Pressey, 

 John L Hodges, Kenneth Henry, Roger Pearson, 

 and Paul Macy, National Marine Fisheries Ser- 

 vice; and William G. Brown, Oregon State 

 University. 



LITERATURE CITED 



Brown, W. G., and F. Nawas. 



In press. Effect of aggregation upon the estimation and 

 specification of outdoor recreation demand function. 

 Western Agric. Econ. Assoc, Annu. Proc. 

 Brown, W. G., A Singh, and E. N. Castle. 



1964. An economic evaluation of the Oregon salmon 

 and sleelhead sport fishery. Oreg. State Univ., Agric. 

 Exp. Stn., Tech. Bull. 78, 47 p. 



