CHINOOK SALMON MARKING, COLUMBIA RIVER 249 



Only ouo adult fish that could be identified as belonging to this experiment 



has been recovered. This one, a 5-year-old, was found during the spring of 1926 



in the spillway from the rearing ponds at the Klaskanine hatchery. The scales of 



this fish are absorbed at the margin, but at least a trace of the fourth winter check 



is to be found at some points. The nucleus is of the composite type. (See figs. 



72 and 73.) The bands of stream and ocean growth in the nucleus are of about 



107 

 equal widths, the combined radius being ry^ millimeter. At the margin of the 



stream growth are five rings, which may be intermediates. 



It is interesting to note that here, as in experiment No. 10, a spring chinook, 

 upon being liberated in a tributary that normally supports only a fall run, left 

 fresh water before the end of the first year. 



EXPERIMENT NO. 12.— BIG WHITE SALMON RIVER HATCHERY, MAY AND JUNE, 1923 



Eggs from: Big White Salmon River and Spring Creek, 1922. 



Reared and marked at: Big White Salmon River hatcherj'. 



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



Number marked: 100,000. 



Liberated: In Columbia River at Big White Salmon River hatchery during May and June, 1923. 



Aye: Appro.ximately 8 months. 



The Big White Salmon River hatchery is situated at the mouth of a small creek 

 (Spring Creek) that empties into the Columbia River about 1 mile below the mouth 

 of the Big White Salmon River. At this point the Columbia River is paralleled 

 closely bj^ a high cliff, and at the base of this cliff a large spring breaks out and forms 

 a small creek, which flows for only a few hundred yards across a sand bar to the 

 Columbia River. It is from this spring that the creek derives its name. By con- 

 structing a dam across the mouth of the creek a rearing pond for salmon fingerlings 

 was formed. The same pond is used for holding adult salmon from the time they 

 reach the creek until they are ready to spawn. In its natural condition the creek 

 was not accessible to salmon and none were known to attempt to enter it, but since 

 the hatchery has been operated there a thousand or more adult chinooks annually 

 attemi)t to find spawning grounds there, and their eggs are taken for artificial 

 propagation. No attempt is made to keep the eggs taken in Spring Creek separate 

 from thos(^. taken in the Big White Salmon River. As a result the fingerlings marked 

 in this experiment developed from eggs taken at both places. 



The first few thousand marked fingerlings were liberated in Spring Creek, but 

 at the mouth of the creek they were attacked by predatory fishes (probably the 

 squawfish, Pfychocheilus oregonensis) , which congregated there in large numbers, 

 presumably attracted by food drifting out from the pond and occasional fingerlings 

 that escaped from the hatchery. The rest of the marked fingerlings were carried 

 to a little cove in the Columbia about 100 yards below the mouth of the creek, 

 where apparently they were not molested by predatory fishes. 



A sam|)le of 50 fingerlings preserved on June 12, 1923, averages 52.2 millimeters 

 (2 inches) in length. Their scales have an average of 5.9 rings and an average anterior 



on c 



radius of -..-,'q millimeters. A typical scale is illustrated in Figure 74. The detailed 

 data are given in Table 26. 



