CONTENTS. 



Page. 



Introduction 3 



History of the investigation 3 



Statement of the problems j 



Methods .' 6 



Presentation of data 7 



Fish from the Columbia River 7 



Fish from the Sacramento River 33 



Miscellaneous collections 42 



Conclusions 45 



Rate of growlh 45 



Development of scales 51 



Migration 6a 



Variations due to sex 65 



Sex proportions 65 



Relative sizes of males and females 66 



Precociously mature males 67 



Practical suggestions 68 



Summary 69 



Bibliography 71 



Explanation of plates , 72 



