THE LENGTH, AGE, AND SEX RATIO OF CHUM SALMON 

 IN THE ALASKA PENINSULA, KODIAK ISLAND, AND 

 PRINCE WILLIAM SOUNDS AREAS OF ALASKA 



by Fredrik V. Thorsteinson, Wallace H. Noerenberg 



and Howard D. Smith, Senior Fishery Biologists 



Fisheries Research Institute, College of Fisheries 



University of Washington, Seattle, Washington 



ABSTRACT 



Data on length, age, and sex ratio of chum salmon from the Alaska Peninsula 

 area from 1951 through 1957, the Kodiak Island area from 1948 through 1951 and 1955 

 through 1957, and the Prince William Sound area from 1952 through 1958 show that 

 age and length composition in these areas varied in a similar manner. Lengths of fish 

 in the 3-, 4-, and 5-year age classes overlapped to such an extent that length was not 

 a useful guide to age. The average age composition for the combined samples was 

 about 10 percent 3-year-olds, 75 percent 4-year-olds, and 15 percent 5-year-olds. 

 Mean age decreased as the season advanced. The percentage of males decreased 

 slightly as the runs progressed. 



INTRODUCTION 



Chum salmon (Oncorhynchus keta) rank third 

 in abundance and value in Alaska's salmon 

 fisheries. Despite their importance, little 

 research has been done on this species. 



The Fisheries Research Institute (FRI), 

 College of Fisheries, University of Washington, 

 collected data on the length, age, and sex ratio 

 of chum salmon incidental to research on 

 other species of salmon in the Alaska Penin- 

 sula, Kodiak Island, and Prince William Sound 

 areas between 1948 and 1958 (fig. 1). No 

 planned program for sampling chum salmon 

 was organized, but data were taken when chum 

 salmon were available and when the time 



Note.--Thorsteinson presently with Bureau of Com- 

 mercial Fisheries, Juneau, Alaska; Noerenberg with 

 Alaska Department of Fish and Game, Cordova, Alaska; 

 and Smith with Fisheries Research Board of Canada, 

 Nanaimo, B.C. 



required for processing them did not conflict 

 with other studies. Because of time limitations, 

 the material was not analyzed at the end of 

 each year, and changes in sampling techniques 

 that might be expected to follow such analyses 

 were not made. As a result, the data presented 

 here are not complete or continuous, and no 

 comprehensive analysis of the chum salmon 

 runs to the three areas for the years when 

 sampling was conducted is made. In spite of its 

 limitations, this material has importance be- 

 cause it is the only biological information 

 concerning past chum salmon runs in the three 

 areas. 



The objectives of this paper are to { 1 ) present 

 basic material collected during the several 

 years; (2) draw tentative conclusions as to 

 intraseasonal and interarea variability in 

 length, age, and sex ratio; and (3) recom- 

 mend methods of sampling for future 

 studies. 



