CHINOOK SALMON MARKING, COLUMBIA RIVER 



223 



closely to the scales of the young fish preserved at the time of marking. Figure 7 

 shows a scale from the one undoubted marked fish, and Figure 8 shows the nuclear 

 area enlarged. The margins of the scale arc rather badly absorbed, and the Avinter 

 band of the fifth year and the beginning of the sixth year's growth do not show. 

 The width of the outer (fifth) summer band is conclusive evidence, however, that 

 the fish was actually in the sixth year and not in the fifth, as might appear to be the 

 case. In the majority of fish taken at this time of year, whose scales are complete, 

 the new growth of the current year has seldom more than three or four rings. Fre- 

 quently the marginal rings are those of the preceding Avinter. The marginal band 

 of sunmier rings sho\vn on the scales of this fish is virtually as wide as the summer 

 band of the preceding (fourth) year and particularly in view of the fact that serious 

 absorption of the scale had taken place, could not possibly be interpreted as being 

 the new growth of the current year. The remainder of the scale offers no difficulty 

 whatever to interpretation. 



EXPERIMENT NO. 2. KLASKANINE HATCHERY, JULY AND AUGUST, 1916 



Eggs from: Willamette River, 1915. 



Reared and marked at: Klaskanine hatchery. 



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



Number marked: 50,000. 



Liberated: In Klaskanine River during July and August, 1916. 



Age: Approximately 11 months. 



A collection of 50 specimens was preserved on July 16, 1916. The average 



length is 81.8 millimeters (3.2 inches). Their scales vary but slightly in general 



appearance. In general the rings are strong and well spaced, indicating that a 



vigorous and uniform growth had l^een maintained. In this respect these scales 



resemble closely those of wild fish, although as a rule the scales of hatchery fish show 



a more irregular growth. ^Vn occasional incidental check is found (see fig. 10), and 



in many the narrower marginal rings indicate that the slower growth of the fall and 



winter had begun. Figure 9 shows a typical scale. The average number of rings 



36.2 

 is 9.3, and the average length of the anterior radius is ^^ millimeters. The detailed 



data are given in Table 2. 



Table 2. — Chinook-salmon fingerlings marked at Klaskanine hatchery July 16, 1916 



