BROOD YEAR 



BROOD YEAR 



Figure 3. — Mean numbers of circuli and lengths of radii from the inner- 

 most circulus to the outer edge of the first fresh-water annulus in 

 Chinook salmon scales from the Alsek, Anchor, Copper, and Taku Rivers, 

 1954-57. 



Table 1. — Mean numbers of fresh-water circuli and 

 mean lengths of radii through the first fresh-water 

 annulus of scales of Chinook salmon from four 

 Alaska rivers for K brood years 



DIFFERENCES IN SCALE CHARACTERISTICS 

 AMONG FOUR RIVERS 



Chinook salmon of both the 1955 and 1956 

 brood years were represented in samples 

 from the four rivers. The numbers of fresh- 

 water circuli and lengths of radii for the four 

 rivers are shown in figure 4 for the 1955 brood 

 year and in figure 5 for the 1956 brood year. 

 Although counts and measurements of these 



« ' 



— * 



— * 



ALSEK 

 N = S2 



ANCHOR 



COPPER 



N:74 



TAKU 

 N = 93 



CIRCULI (NUMBER) 



LENGTHS OF RADII (MM.) 



Figure 4. — Numbers of circuli and lengths of radii from 

 the innermost circulus to the end of the first fresh-water 

 annulus of scales of Chinook salmon from the Alsek, 

 Anchor, Copper, and Taku Rivers in the 1955 brood 

 year. The horizontal line defines the range of sample 

 observations; the vertical line intersecting the range 

 denotes the sample mean; and the shaded rectangle 

 represents + 1 times the standard error of the mean. 



ALSEK 

 N:300 



ANCHOR 

 N = 26 



COPPER 

 N:25Z 



TAKU 

 N:237 



CIRCULI (NUMBER) 



LENGTHS OF flaOlKMM,) 



Figure 5. — Numbers of circuli and lengths of radii from 

 the Innermost circulus to the end of the first fresh-water 

 annulus of scales of Chinook salmon from the Alsek, 

 Anchor, Copper, and Taku Rivers in the 1956 brood year. 

 The horizontal line defines the range of sample observa- 

 tions; the vertical line Intersecting the range denotes 

 the sample mean; and the shaded rectangle represents 

 ± 1 times the standard error of the mean. 



