each year, furnishing the main supply of eggs 

 for Spring Creek Hatchery and supplementing 

 the egg supply at other Columbia River hatch- 

 eries. Runs to Big White Salmon River are 

 still utilized as an additional source of egg 

 supply. Almost all of the fish hatched at this 

 station are released into the Columbia River 

 at the hatchery or into Big White Salmon 

 River. In recent years large numbers of green 

 and eyed eggs in excess of hatchery capacity 

 have been transferred to other hatcheries and 

 other agencies. 



During the last several years it has become 

 increasingly apparent that the rate of return of 

 adult Chinook salmon to Spring Creek Hatchery 

 greatly exceeds that to any other hatchery in 

 the Columbia River system. If the factors in- 

 fluencing these returns can be discovered, it 

 is likely that improved techniques can be de- 

 vised to increase production at other existing 

 hatcheries and to design better hatcheries in 

 the future. In view of the critical condition 

 of the stocks of fall chinook salmon in the 

 Columbia River system and the rapidly in- 

 creasing effects of expanding hydroelectric 

 projects in this system, the solution of this 

 problem has become a matter of great urgency. 



Before the general problem can be ap- 

 proached, however, some specific questions 

 must be answered, and basic data must be 

 examined to obtain at least a partial under- 

 standing of what the problems really are. For 

 example, in recent years large numbers of 

 unfed fry have been released in late winter 

 and relatively large numbers of hatchery 

 reared fingerlings in the spring. The direction 

 of future study obviously depends on a knowl- 

 edge of the relative survival of these two 

 groups. In addition, there is a question whether 

 the returns to Spring Creek Hatchery could 

 be affected by such factors as relative avail- 

 ability to the fisheries, straying from other 

 hatcheries, or naturally produced runs. If 

 comparisons of return rate are to be made 

 between Spring Creek Hatchery and other 

 hatcheries or with naturally produced stocks, 

 some quantitative measure of the relative 

 effects of these factors may be of value, even 

 though existing evidence may be sufficient to 

 demonstrate that none of these factors has a 

 controlling influence on the returns. 



On January 4, 1960, the Fisheries Research 

 Institute of the University of Washington con- 

 tracted with the Bureau of Commercial Fish- 

 eries for work on the following four aspects; 



1. An assembly of all relevant data. 



2. Preliminary analysis of these data (future 

 analysis may be needed under aspect 4). 



3. An evaluation of the problems involved. 



4. An outline of specific experiments with 

 an order of priority. 



Because of the time required by the first 

 three aspects and because of the number and 

 type of problems arising under the third as- 

 pect, proposed studies for the fulfillment of the 

 fourth aspect have been somewhat general and 

 no order of priority has been suggested. 



DEVELOPMENT OF BASIC DATA ON THE 



RELEASE OF YOUNG AND THE RETURN 



OF ADULT SALMON 



Any study of hatchery operations requires 

 information on the number of fish planted and 

 the number returned. Two sources of such data 

 were obtained from the Little White Salmon 

 Hatchery office staff. The "Production Sheets" 

 which were tabulated from the standard monthly 

 reports, provided yearly records of individual 

 releases or transfers of fish and eggs from 

 Spring Creek Hatchery beginning in brood 

 year 1939. These are reproduced in a slightly 

 modified form in appendix table 1 for eggs 

 taken at Spring Creek and in appendix table 2 

 for eggs taken at Big White Salmon River. 

 Releases of the 1939 brood are not included in 

 the reproduced tables since no information on 

 source of eggs is available. 



In appendix table 3, fish are grouped accord- 

 ing to size (number per pound) at time of re- 

 lease in the two areas; and the total number, 

 total weight, and the' size distribution for all 

 fish released at Spring Creek and Big White 

 Salmon River are listed for each brood year 

 since 1940. Fry' and fingerling releases are 



* Fry (and fingerlings)- are defined as fish smaller 

 than (or larger than) 500 per pound. The justification 

 for these definitions is given in a later section. 



