INTRODUCTION 



Many significant changes in the environmental conditions 

 ■which affect fisheries in Sacramento River have resulted from 

 the operation of Shasta Dam. Some of these have been measured 

 (Moffett, 1949) and others are now being brought to light. 

 Alterations in the fish populations and their djmamios were 

 first reflected by the activities of sports fishermen. The 

 river below Shasta Dam originally supported no continuous 

 sports fishery. It has now developed salmon and trout fish- 

 eries during every month of open season. The increasing 

 number of sportsmen who are turning to the Upper Sacramento 

 River is indicative of the magnitude of readjustments that are 

 occurring in the fish populations of Sacramento River below Shasta 

 Dam. 



A study was initiated by the U. S. Fish and Wildlife Service 

 in August of 194"^ to learn something of the population readjust- 

 ments among the game fishes and interrelated species, and to de- 

 termine the extent and value of the sports fishery dependent on 

 these fish populations. An effort was also made to arrive at 

 some method of sampling to obtain accurate estimates of the 

 sports fishing effort and catc>-o The area studied extends from 

 Keswick Dam to Chico Creek and is referred to in this report as 

 the Upper Sacramento River (see map) . 



This study is a part of the Central Vallej'- Fishery Investi- 

 gations of the Fish and Tfildlife Service. The former investigation 

 chief. Dr. James If. Moffett, and members of his staff gave much 

 valuable assistance during the study. Mr. James A. Blaisdell euid 

 Mr. Kenneth L. Liscom assisted in gathering and compiling creel 

 census data. Many valuable suggestions have been received from 

 other biologists of the Fish and Wildlife Service and those of the 

 California Division of Fish and Game. Fishing guides and boat 

 landing operators in the Upper Sacramento River area have been 

 very cooperative during the conduct of the study. 



OAME FISH POPUIATIONS 



Before the construction of Shasta Dam the Sacramento River below 

 Redding was typical of other lowland rivers in California's Central 

 Valley. During the sxxmmer months, river flows became quite low and 

 water temperatures rose above optimum ranges for salmonoid fishes. 

 Therefore, during the summer only warm water species were present. 



