CHINOOK SALMON MARKING, COLUMBIA RIVER 



229 



1 fi n 



and the average length of their anterior radii is ^ millimeters. No peculiarities 



are noticeable in the scale growth. A typical scale is shown in Figure 32. The 

 detailed data for these 45 specimens are given in Table 7. 



T xB-LVi 7. —Chinook-salmon fingerlings marked at Little White Salmon River hatchery July 18, 1917 



One adult specimen, a female 27 inches (69 centimeters) in length and weighing 

 10.5 pounds (4.8 kilograms), was recovered. It was taken durmg spawning opera- 

 tions in the Little White Salmon River on October 13, 1920. The anterior half of 

 the dorsal fin was somewhat regenerated, but there was little question of the reliability 



of the mark. 



The scales show such an extreme amount of absorption (fig. 33) that they are 

 useless for determining the age. Only one complete year of the ocean growth remains. 

 The nucleus is usually large and poorly differentiated and probably represents the com- 

 posite type to be discussed later. A slight check may be seen about four rings from 

 the center, which possibly was formed at or just before the time when the fish was 

 marked and liberated. It is impossible to determine the exact boundary of the first 

 year's growth, but apparently there is an imusually wide band of intermediate rings, 

 including perhaps as many as 16 of the rings immediately within the undoubted ocean 

 growth. 



The fish that spawn in the McKenzie River, from which the fish marked in this 

 experiment originated, enter the mouth of the Columbia in the spring and therefore 

 constitute part of the so-called "spring" run, which is of the highest quality and the 

 maintenance of which is especially to be desired. The primary object of this experi- 

 ment was to test the effect of liberating young fish belonging to a race that normally 

 enters the river during the spring into a stream such as the Little \^'iiite Salmon 

 (which is populated mainly by a race of fish that normally enters the river during 

 late summer or fall) . The great amount of absorption exhibited by the scales of the 

 one specimen recaptured would indicate that it had spent considerable time in fresh 

 water. The absorption is noticeably greater than that of the scales of other fish 

 taken during the spawning season in the Little White Salmon. (See fig. 14, showing 

 a scale from a fish only 3 years old.) If the amount of absorption of the scales can 

 be taken as indicating the length of time spent in fresh water, it would follow that 

 this individual had entei'ed much earlier than the usual run that populates the Little 

 10510T— 29 2 



