listed by numbers released in appendix table 4 

 and by pounds released in appendix table 5. 



For the most part, standard annual reports 

 on Spring Creek Hatchery (submitted under 

 various titles) furnished the necessary infor- 

 mation on the adult returns to both Spring 

 Creek and Big White Salmon River. Records 

 for Spring Creek Hatchery returns are com- 

 plete since all fish entering the hatchery 

 ladder are counted and the total number of 

 males, females, and "jacks" (2-year-old 

 males) is recorded; there is no possibility of 

 natural spawning at Spring Creek Hatchery. 

 Such is not the case, however, at Big White 

 Salmon River. Fish entering this system 

 cannot be accurately counted unless they 

 migrate upstream to the hatchery rack site. 

 In some years many fish spawn below the 

 rack since it is located some distance above 

 the mouth of the stream. 



1950, 1952, 1954, 1957, and 1958.' For the 

 return years 1951, 1953, 1955, and 1956, 

 estimates of the total egg deposition, but no 

 estimates of numbers of fish, are found in the 

 reports. This estimated egg deposition has been 

 converted to number of females, assuming 

 5,000 eggs per female. In 1945 very few fish 

 spawned naturally, and, since no actual figure 

 was given, it has been assumed that no natural 

 spawning occurred. In 1946 the annual report 

 lists the natural spawning fish as being pre- 

 dominantly males, so no natural spawning 

 females have been added to the number of 

 females handled in the hatchery operations. 

 The figure for the 1947 return is a minimum 

 one since it includes only those fish which 

 were counted past the rack or which remained 

 between the racks when operations ended. 

 Large numbers of fish are known to have 

 spawned below the racks, but their numbers 

 were not estimated. 



There are several years when the number of 

 fish handled at the Big White Salmon rack in 

 spawn-taking operations was unrecorded in the 

 annual reports and the number of females 

 could be estimated only from the reports on 

 eggs taken and the average number of eggs 

 per female. Appendix table 6 lists the number 

 of males, females, and jacks handled in op- 

 erations at Spring Creek Hatchery and the 

 Big White Salmon River rack. These figures 

 do not include any estimates of the number of 

 natural spawners in Big White Salmon River. 

 No information was available for 1943, 



A rough estimate of the number of females 

 which spawned naturally in the river was made 

 (appendix table 7). These estimates are based 

 on two assumptions. The first is that the esti- 

 mated total number of natural spawners is 

 reasonably correct. The second is that the 

 sex ratio of the fish handled at the rack on the 

 river is representative of the sex ratio in the 

 natural spawning population and not the result 

 of selection for a particular sex or size of 

 fish. One exception will be mentioned later. 

 Using the sex ratio of the fish handled at the 

 rack, the numberof naturally spawning females 

 was obtained for the return years 1948 through 



SELECTION AND ADJUSTMENT OF 

 VARIABLES FOR STUDY 



A major aim of the present study is to re- 

 late adult production quantitatively with fry 

 and fingerling releases. In order to study such 

 a relationship it is first necessary that such 

 variables be defined. 



Index of Adult Production 



An adequate measure of adult production 

 from the releases of each brood year is a 

 primary requirement. Development of such a 

 measure for hatchery-produced fall chinook 

 salmon is complicated by several variations: 

 age at maturity, degree of straying to and from 

 the parent stream, and fishing intensity (ocean 

 troll, river gill net, and ocean and river 

 sport). 



Effects of variation in age at maturity . — 

 Returning fall chinook salmon vary in age 



No estimates for 1957 and 1958 were found in the 

 annual reports. The figures for these 2 years were 

 derived from estimates of a total of 3,500 fish spawning 

 in both years (by Clyde Adams, hatchery superin- 

 tendent, and Irvin Brock, hatchery foreman). 



