1 



5o A Method of Computing Mortalities and Replacements 



By 

 Ralph P» Silliman l/ 



CONTENTS 



Preface Page 



Introduot iono ooooooo»o»»oooooo«ooo X69 



Basic assumptions oooooooosoooooooooo 169 



Known quantities and relations hi pso oooooooooo 170 



Determining total mortality oooooooooooooo 171 



Separating fishing mortality from natural mortality o o 172 



Determining rate of recruitment eoooooaooaoo 175 



Effect of errors in original data «o>ooo<>oaoo 177 



Summaryo »o«oooooo«oooeeooooooooo 1/9 



Literature cited aooeo«oooooooooaaooo 179 



l/ Now Chief, Section of Anadromous Fisheries, Branch of Fishery Biology, 

 "" Fish and Wildlife Service, Washington^ D. Cu 



168 



