FLUCTUATIONS IN ABUNDANCE OF RED SALMON, 



ONCORHYNCHUS NERKA (WALBAUM), OF 



THE KARLUK RIVER, ALASKA 



By Joseph T. Barnaby, A. M., Aquatic Biologist, Division of Fishery Biology, Fish and Wildlife 



Service 



CONTENTS 



Page 



Introduction 237 



Statistical history of the fishery 23S 



Age at maturity 241 



Spawning populations 247 



Total populations 252 



Returns from known spawning popula- 

 tions 255 



Chemical analyses of lake and stream 



waters 260 



Change in age composition of the popu- 

 lation 207 



Seaward migrations 272 



Sex ratios of adult fish 275 



Marking experiments 277 



Marking of Karluk River red 



salmon 281 



Page 

 Marking experiments — Continued. 



Recovery of marked fish 281 



Experiments in 1926 282 



Experiments in 1927 and 1928 283 



Experiments in 1929 283 



Experiments in 1930 281 



Experiments in 1931 286 



Experiments in 1932 287 



Experiments in 1933 289 



Discussion of marking experi- 

 ments 290 



ality in fresh water 291 



Summary and conclusions 292 



Literature cited 294 



INTRODUCTION 



One of the major problems of the Federal Government on the Pacific coast is the 

 coDservation of the Alaska salmon resources which yield more than 280 million pounds 

 of salmon to the commercial fisheries each year. In order to conserve these re- 

 sources, so as to provide for an optimum yield each season, it has been found neces- 

 sary to impose certain regulations on the fishing industry. These regulations aim 

 primarily to provide an adequate escapement of the salmon to the streams each 

 season so that they may reproduce and maintain the supply. 1 



Knowledge of fluctuations in the abundance of salmon populations provided 

 the basis upon which the regulations were formulated. Since the commercial catch 

 records gave insufficient and frequently unreliable information on the abundance 

 of salmon, picket weirs were established in a number of important salmon rivers 

 through which the fish were counted on their upstream migration to the spawning 

 grounds. The count of the number of salmon migrating into a river, together with 

 the record of the commercial catch in the locality of the river, furnished information 



» Paciac salmon spend the early part of life In fresh water, the time spent there depending on the species and locality. They 

 then migrate to tho ocean and after a varying period of time return to fresh water to spawn. Fishery Bulletin 39. Approved for 

 publication May 6, 1940. 



237 



