Procedures") to estimate the catch of unmarked 

 hatchery fish, then marked fish were added to 

 estimate the total catch. 



An additional calculation was required before 

 estimating the unmarked catch associated with 

 the marked 1966-brood Leavenworth Hatchery 

 fish because of the recovery of 1966 brood D-Ad- 

 only marks. The recovery was due to either 

 regeneration or nondetection of D-Ad-maxillary 

 marks (see "Bias Associated with Marks"). 

 Therefore the estimated catch of 1966 brood 

 D-Ad marks had to be apportioned between the 

 estimated catches of D-Ad-RM and D-Ad-LM 

 marks before calculating the catch of unmarked 

 1966-brood fish. The D-Ad marks were appor- 

 tioned by the ratio of their occurrence at the 

 time of release. At Leavenworth Hatchery, 5,081 

 D-Ad marks were estimated to have been re- 

 leased with the D-Ad-RM marks. Below Bonne- 

 ville Dam, 4,393 D-Ad marks were estimated to 

 have been released with the D-Ad-LM marks. 

 This is a total release of 9,474 D-Ad mai'ks of 

 which 54% (5,081/9,474) came from D-Ad-RM 

 marks and 46% (4,393/9,474) came from D-Ad- 

 LM marks. These ratios were used to apportion 

 the estimated catch of 6G6 D-Ad marks (Appen- 

 dix Table 5a) between the D-Ad-RM and D-Ad- 

 LM marked fish in each of the fisheries. For 

 example, 88 D-Ad marked coho (Appendix 

 Table 5a) were estimated to have been caught in 

 the Washington sport fisheries in 1969. Using 

 the occurrence percentages of the D-Ad marks at 

 release, 88 X 0.54 = 48 were calculated to be from 

 D-Ad-RM marks and 88X0.46 = 40 were 

 calculated to be from D-Ad-LM marks. This 

 apportioning was done for each fishery and re- 

 sults are in Appendix Table 4b. 



The estimated catches of marked fish used to 

 calculate the catches of unmarked hatchery fish 

 are in (1) Table 6a for the estimated 1965 brood 

 D-Ad, Ad-LM, Ad. and Ad-RM marks captured 

 in the ocean and Columbia River fisheries; (2) 

 Table 6b for the estimated ocean and Columbia 

 River catches of 1966 brood Ad-LM, Ad, and Ad- 

 RM marked fish; and (3) Appendix Table 5b for 

 the catches of marked 1966-brood Leavenworth 

 coho salmon. Appendix Table 7 presents the 

 resulting estimated catches of unmarked hatch- 

 ery fish. 



The estimated total catch of Columbia River 

 hatchery fish (Appendix Table 8) was obtained 

 by adding the estimated catch of marked fish 



FISHERY BULLETIN: VOL. 72. NO. 1 



(Tables 6a and 6b) to the estimated unmarked 

 catches (Appendix Table 7). The resulting catch 

 estimates may affect management decisions in 

 years when no marking studies take place. 

 Therefore, as a final step, we divided the esti- 

 mated catch of each mark in each fishery (Tables 

 6a and 6b) by the estimated relative survival for 

 that mark (see "Relative Survival of Marked 

 Fish") to obtain a theoretical catch of marked 

 fish assuming no marking mortality. The results 

 were then added to the estimated unmarked 

 catch (Appendix Table 7) to obtain a theoretical 

 total catch of Columbia River hatchery coho 

 salmon. The results are in Table 7 by region of 

 recovery, type of fishery, and year of capture. 

 The table includes the estimated sport catches 

 of hatchery fish in Columbia River tributaries 

 where no creel census took place. This is broken 

 down in detail by year of capture, brood, and 

 stream in Appendix Table 9. 



An estimated total of 2,188,172 Columbia 

 River hatchery coho would have been caught 

 during the 3 years of sampling had no marking 

 taken place. This is about 16% of the total catch 

 in areas sampled (Table 3) of 1965- and 1966- 

 brood coho caught during 1967-69 (Table 4) — 

 13% for the 1965 brood and 21% for the 1966 

 brood. Another useful statistic is the catch/1,000 

 fish released. For the combined 1965 and 1966 

 broods, this was 55/1,000—50/1.000 for 

 the 1965 brood and 61/1,000 for the 1966 brood 

 (Tables 2 and 7). 



ECONOMIC EVALUATION 



A main purpose of this paper is to develop 

 benefit/cost ratios for the 1965 and 1966 broods 

 of coho salmon from Columbia River hatcheries. 

 To develop these ratios, estimates must be made 

 of (1) the costs of rearing the 40.1 million smolts 

 released (Table 2) and (2) the value of the theo- 

 retical catch of 2,188,172 coho (Table 7). The 

 rearing costs will be presented first. 



Cost Accounting 



Production costs are broken down into two 

 categories: (1) amortized construction costs or 

 capital costs and (2) operational costs. 



Capital 



The "annual imputed capital charge" for each 

 hatchery was computed by amortizing the capi- 

 tal expenditures at each hatchery into 30 equal 



I 



152 



