226 



BULLETIN OF THE BUREAU OF FISHBK1E8 



a large proportion of cases the scales are characterized by a distinct nan-owing, an 

 incidental check, some five or six rings from the center. A narrowing of the marginal 

 rings is typically present also, indicating the beginning of the slower winter growth. 

 Figure 21 shows a typical scale with a distinct incidental check five rings from the 

 center and the narrower winter rings at the margin. Figure 20 shows a scale from the 

 smallest fish of the collection. This fish was only 47 millimeters (a little less than 2 

 inches) in length, and the scale shows only five rings, with no indication of either the 

 incidental check or the marginal winter rings. 



Table 5. — Chinook-salmon fingerlings marked at Bonneville hatchery September IS, 1916 



Thirty-six adult fish from this experiment were reported from the commercial 

 fishery during the season of 1920, when the fish were in theu- fifth year. Table 6 

 gives the data regarding these recaptiu-es. The males average 33. S inches (85.8 

 centimeters) in length and 22.5 pounds (10.2 kilograms) in weight. The females 

 average 35.3 inches (89.7 centimeters) in length and 20.7 pounds (9.4 kilograms) in 

 weight. One record of 40 pounds in weight, which is obviously in error, has not 

 been considered in the average. No significance can be attached to the lower aver- 

 age length for males than for females, as the average for the former is based on only 

 four specimens and, as previously mentioned, the measurements are subject to con- 

 siderable error. With reliable data, males usually are found to average greater than 

 females in both length and weight. 



