CONTENTS 



Page 



Introduction 1 



Development of basic data on the release of young and the return of adult salmon 2 



Selection and adjustment of variables for study 3 



Index of adult production 3 



Effects of variation in age at maturity 3 



Effects of local straying 6 



Effects of fisheries 7 



Variables concerned with hatchery releases 8 



Analysis of data: 



Regression studies, 1941-49 brood years 9 



Relationship between fingerling releases and returns for brood years 1949-55, and 



indications of reduced survival rate in recent years 11 



Factors coincident with change in production rate 13 



Incidence of infection with acid-fast bacteria (tuberculosis) 13 



Coagulated yolk disease 13 



Increased crowding 14 



Composition of diet 14 



Handling of fry and fingerlings 14 



Temperature effects 15 



Egg and early fry stage 15 



Temperature differential at time of release 15 



Problems and suggested studies 17 



Initial problems 17 



Relative production of fry and fingerling releases 17 



Contribution to fisheries 17 



Straying 17 



Additional problems: 



Reduction in productivity 17 



Relationship between problems at Spring Creek Hatchery and problems at other 



hatcheries 18 



Apparent change in modal age of maturity 18 



Disposition of eggs 18 



Continuation of fry releases. Time, place, and manner of release 19 



Acknowledgments 20 



Literature cited 20 



Appendix 22 



ill 



