CHINOOK SALMON MARKING, COLUMBIA RIVER 233 



adult fish in tlio rearin<r ponds (which they had entered with the intake water) 

 prompted a more thorough investijiation of the creek. Between the hatclaery 

 station and a small power dam, about 1 mile above, 5 living and 14 dead fish were 

 found. All were inspected carefully for the absence of fins, but only one marked 

 fish was found. Unquestionably these fish entered the creek early in the spring, 

 because not only was the dam impassable, but the creek became so low early in the 

 summer that nearly all of the water was diverted through the ponds, leaving the 

 creek virtually dry for a distance of several hundred feet. 



The appearance of an occasional adult chinook salmon in Herman Creek during 

 the spring is not an unusual occurrence, but this was the first time that any number 

 of spring chinooks had been reported from there. A second run was reported in 

 1926, when 130 spring chinooks ran into the creek. 



Additional data regarding the tendency of salmon to return to a particular 

 tributary to spawn were secured from later experiments. 



The scales of the adult fish present nothing unusual. Their nuclei are typical 



of the stream type and are identical with the scales of the young fish at the time of 



liberation. (See figs. 37 and 39.) The majority of those haviiig perfect scales 



show an incidental check inclosing an area marked by an average of 8 rings and 



28 4 . . 

 having an average anterior radius of y^ millimeters. As mentioned above, the 



scales of the young fish showed an incidental check inclosing an average of 8.4 rings 



The 

 47.5 



30 1 

 and with a radius of ysW millimeters — a remarkably close correspondence. The 



1 ^U 



average total number of nuclear rings is 16.2, and the average total radius is 



millimeters. (See Table 9.) The scales of the adult fish are characterized further 

 by a comparatively small growth during the first year in the ocean. Figures 36 

 and 38 illustrate typical scales from mature fish in their fifth and sixth years, 

 respectively. 



EXPERIMENT NO. 7. BONNEVILLE HATCHERY, OCTOBER, 1920 



Eggs from: Willamette, McKenzie, and Santiam Rivers, 1919. 



Reared and marked at: Bonneville hatchery. 



Mark used: Removal of adipose fin and right ventral fin. 



Number marked: 65,000. 



Liberated: In Tanner Creek during October, 1920. 



Age: Approximately 13 months. 



A sample of 50 fingerlings preserved on October 14, 1920, averages 96.6 centi- 

 meters (3.8 inches) in length. The rings of the scales are regular in shape and evenly 

 spaced, giving evidence of comparatively rapid and uninterrupted growth. The 

 average number of rings is 15.3, and the average length of the anterior radius is 



Yi^ millimeters. A typical scale is shown in Figure 40. The complete scale and 



length records are given in Table 11, 



