CHINOOK SALMON MARKING, COLUMBIA KIVER 



225 



Adults developing from these marked fish were found among the spawning 

 fish taken for purposes of artificial propagation in the Little White Salmon River in 

 191S, 1919, and 1920, when the fish were in their third to fifth years. One 3-year-old, 

 four 4-year-old3, and one 5-year-old were recovered in this way. In addition to 

 those taken in the parent tributary, one was taken in the lower Columbia in 1919 

 and another was. taken by purse seine in the ocean near the mouth of the Columbia 

 in 1920. Table 4 gives the detailed data regarding the adult fish. 



T.vBLE 4. — Chinook salmon marked at Little White Salmon River hatchery during the summer o] 1916, 

 when approximately 10 months old, and recovered during the seasons of 1918, 1919, and 1920 



' Date not reported. 



The scales of the fish recaptured at the hatchery were absorbed to such an extent 

 that no part of the original margins remained. As there is no criterion by which the 

 amount of absorption may be determined, it is impossible to determine the age from 

 such scales. A scale from the 3-year-old fish recovered at the hatchery is illustrated 

 in Figure 14. The two fish taken before they reached the spawning grounds have 

 complete scales marked by the expected number of summer and winter bands. Scales 

 from these fish (4 and 5 years old, respectively) are shown iu Figures 15 and 17. 



The nuclei of the scales of these fish present peculiarities that may be discussed 

 more conveniently in connection with the scales of the adult fish in experiment No. 8. 

 The discussion of them therefore will be deferred until the latter have been considered. 



EXPERIMENT NO. 4.— BONNEVILLE HATCHERY, SEPTEMBER, 1916 



Eggs from: Umpqua River, 1915. 



Reared and marked at: Bonneville hatchery. 



Mark used: Removal of right ventral fin and posterior half of dorsal fin. 



Number marked: 25,000. 



Liberated: In Tanner Creek during September, 1910. 



Age: Approximately 12 months. 



Fifty specimens were preserved on September 13, 1916. These average 67.6 milli- 

 meters (2.7 inches) in length. The average number of rings on the scales is 9.2, and 



31 8 

 the average length of the anterior radius is Y<i?) millimeters. (See Table 5.) In 



