Table 3 . --Variability in size of 4-year-old chum salmon in three time periods 

 in catch, Alaska Peninsula, 1951, 1953-57; Kodiak Island, 1949, 1955-57; 

 Prince William Sound, 1953, 1956, 1958 



Mean lengths of chum salmon of both sexes 

 in age class 4 were slightly greater in the 

 third period in the Kodiak Island area. Means 

 were similar in all three periods on the 

 Peninsula — for males the range was only 7 

 mm. The means showed no appreciable change 

 with time of sampling in Prince William 

 Sound. 



Age composition. — Age composition of the 

 combined samples for all of the years is given 

 by the three time periods in table 4 and 

 shown graphically in figure 3. The data are so 

 few in the first period for the Kodiak Island 

 and Prince William Sound areas that only 

 males from the Kodiak Island area are plotted 

 in the figure. The age composition shifted with 

 time: 3-year-old fish increased and 5-year-old 

 fish decreased in relative abundance as the 

 season progressed. Four-year-olds were dom- 

 inant throughout the season and made up about 

 three-fourths of the total run. This trend 

 toward younger fish as the season advanced is 

 not an artifact of combining the data. Catch 

 data from the East Anchor Cove-Ikatan Bay and 

 Izembek Bay areas of the Alaska Peninsula 

 show the same sequence of shift in ages (table 5). 



80 

 60 

 40 

 20- 

 



MALES 



g 3 YEARS 

 n 4 YEARS 

 5 YEARS 



FEMALES 



PRINCE WILLIAM 

 SOUND 

 53: 

 98 



Figure 3.--Percentage 3-, 4-, and 5-year-old chum 

 salmon in three time periods in the catch in Alaska 

 Peninsula, Kodiak Island, and Prince William Sound 

 areas. 



