On the basis of the preceding summary, esti- 

 mates of tlie total catch of 1961-broocl hatchery 

 fish were made and are presented in table 17. These 

 estimates were obtained from equation ((i) and 

 the estimated numbers of marked fish in tiie catcli 

 (table 10) . For example, estimated 1964- total catch 

 of hatchery fish ( 115,755) Ijy tlie ocean commercial 

 fisheries was computed as follows. First, the 

 mai'ked to unmarked ratio required in equation 

 (6) was estimated by the product of the marked 

 (Ad-PvM) to unmarked ratio, 0.1 19:5, at release 

 (table 4) and the assumed relative survival of 

 marked fish, 0.70. The catch of unmarked hatchery 

 fish (104,227) was tlien estinuxted from the ratio: 

 104.227 = 8,704/ (0.1 19?.) (0.7) where 8,704 is the 

 estimated catch of Ad-RM marked fish (including 

 Ad-oidy). Estimated catches of the other markeil 

 hatchery fish were 2,031, G18, 89, and Si^ for tlie 

 Ad LV-RM, Ad-R\'-PiM, I.V RM, and RV-RM 

 marks, respectively.'- The total catch of hatchery 

 fish in 1964 is then simply the sum of the catches of 

 marked and unmarked fish (i.e., 115,755=104,227 

 + 8,704-^2,031 + 618 + 89 + 86). 



Table 17. — Estimated catch of hatchery fall chinook salmon 

 of 1961 brood by type of Jishery and year of capture, 

 196.1-66 



Fisliery typri 



Year of catch 



1965 191)6 Total 



- - Number of fish 



Ocean sport 7,597 27.487 7,514 1,082 43,680 



Ocean commercial 43 115,755 37,441 4,797 158,036 



Columbia River sport 272 33 305 



Columbia River commercial 1,942 32,349 4.8,275 2,739 86,305 



Total 9.582 175,863 93,263 8,618 287,326 



During the 4 years of sampling an estimated 

 287,326 fall chinook salmon that originated from 

 the 12 liatcheries were caught. This number com- 

 prised tdjout 10 percent of the total catch (2,812,- 

 949) of 1961-brood cliinook salmon in the fisheries 

 sampled. The fish from these hatcheries accounted 

 for 2;i. 11, !), and 4 percent of the catches of 1961- 

 brood chinook salmon in 1963, 1964, 1965, and 

 1966, resjDectively. 



An aj^proximate interval estimate" (95 percent 

 confidence interval) for the total catch of hatcherv 



'-Total 1-stinmtMS for LV-KM and RV-K.M marks ilo not inoUldc 

 the corresponding partial marks. 



" Calculated by assuming that the variance of tlic estimate of 

 the marked to unmarked ratio, (.1193) (0.7) =n.0S.3,"i, In the 

 catch is such that 2 times the standard deviation is equal to 

 O.ns.'!.-). 



fish is 258,593 to 316,059 (287,326±10 percent). 

 This estimate is rough and is presented solely to 

 indicate tlie general level of precision of the esti- 

 mated catch of hatchery fish (287,326) obtained 

 under the assumptions stated previously. Sources 

 of error other than sampling variation are in fact 

 more important at this time. For example, if sur- 

 \i\al of marked relative to unmarked fish was 60 

 or 100 percent, rather than the assumed 70 percent, 

 then the estimated catcli of hatchery fish would 

 ha\ e been 330,465 or 209,672, resi)ective]y. Hoth of 

 these values are well outside the interval esti- 

 mate. It should, therefore, be clearly understood 

 that the above estimated catch of hatchery fish 

 (287,326), although reasonable (but probably 

 minimal), is preliminary. 



ESTIMATED VALUE OF CATCH FOR 

 1%1-BROOD HATCHERY FISH 



To determine tlie benefit to cost ratio of tlie 1961- 

 bnrod-year releases of fall chinook salmon from 

 the 12 hatcheries under study, estimates were made 

 of production cost for the 53.6 million fish released 

 and of the net value of the 287,326 fish caught by 

 the sport and commercial fisheries. In addition to 

 the release of 53.6 million fish from the 12 hatch- 

 eries, 3.86 million fish were released from Aber- 

 natliy, Speelyai, Toutle, Klaskanine, and Sandy 

 Hatcheries. By making certain assumptions it is 

 also possilile to estimate the catch and value of 

 these releases. 



The cost of producing fish released from tlie 12 

 hatcheries was estimated from 1962 fiscal year 

 costs at individual hatcheries. Costs were appor- 

 tioned between the brood year-species groui)s at 

 each hatchery on the basis of either estimated rel- 

 ati\e man-hours expended or relative size of each 

 group. At each liatchery costs were divided into 

 three categories: 



1. Amortized and discounted capital invest- 



ment 



2. Fish food and drugs 



3. Operational costs other than food 

 Capital investment in the hatcheries was 



amortized over 50 years and was cliarged a simple 

 intere.st rate of 5 percent per annum,'* which 

 amounts to 7 percent of the total capital in\'est- 



1* .\mortization period and discount rate are from J. \. Crutch- 

 field, Department of Economics, University pf Washington. 

 Seattle, Wash, (personal conimnnication ). 



';84 



U.S. FISH AXD WILDLIFE SERVICE 



