220 



BULLETIN OF THE BUREAU OF FISHERIES 



cents was paid during the season of 1927. Most of the returns have come as a result 

 of these rewards. 



On account of the manner in which the data were collected it is necessary to 

 accept the measurements of the fish with some reservation. In all probability the 

 data as to sex are reliable, but those as to length, weight, and time of capture are 

 less dependable. Measurements of length and weight were made by persons usually 

 untrained, and it is more than likely that instruments for taking accurate measure- 

 ments were not available to them. It is also pos- 

 sible that the length was measured differently; for 

 example, the rays of the caudal fin may have been 

 included in some measurements and excluded from 

 others. 



These experiments were planned with several 

 purposes in mind. First and foremost they were 

 designed for the very practical purpose of testing 

 the relative efficiency of various procedures in 

 artificial propagation. It is believed that this 

 method of investigation, more than any other, 

 promises information of vital importance in the 

 upbuilding and improvement of current hatchery 

 practices. The experiments also bear upon impor- 

 tant problems in the life history of the salmon, such 

 as the home-stream theory both as apphed to entire 

 branchioste9al rays river systems and to the tributaries of a single 



Fig. 4.-Diagram of the gui cover of a salmon, system, the factors afi'ecting the age at maturity, 



showing extent of injury and regeneration in . . . i i i i • ' 



the case of yearlings marked with a clip in the the time oi entcrmg the I'lTcr, and the hereditary 

 gui cover at Bonneville hatchery during the eharacter of the quality of the flcsh. And finally, 



spring of I9I6. Experiment 1. Broken line, . . 



X — X. indicates approximately the original an examination of the scales of marked fish, the 



mark as placed on the young fish. The dotted v*i„r i.-u*i _ -i i*ii • ^i 



lines indicate the edges of the bones, and the history of which IS luiown aids materially m the 

 stippled areas the parts filled in with soft tissue interpretation of various difficult tyi^cs of scales fre- 



on the gill cover of the returned adult fish , , , , . i I'l  ,. . , 



quently encountered in general collections from the 

 regular runs. On this account special attention has been paid to the scales and detailed 

 measurements and ling counts are given in the accounts of the several experiments. 



EXPERIMENT NO. 1. BONNEVILLE HATCHERY, FEBRUARY-APRIL, 1916 



Eggs from: Willamette River, 1914. 



Reared and marked at: Bontieville hatchery.'' 



Mark used: Removal of adipose fin and U-shaped clip in right gill cover. 



Number marked: 4,000. 



Liberated: In Tanner Creek during February, March, and April, 1916. 



Age: Approximately 18 months.' 



These fish had been reared in the ponds at the hatcherj'^ with a much larger 

 number of sockeyes of the same age. It was during the course of the marking of 

 50,000 of the sockeyes that these few yearling chinooks were marked incidentally. 

 As no special attempt was made to select chinooks, comparatively few were handled. 



4 For location of hatcheries and fishery locations, see fig. 1. 



• The ages given are counted from the time the eggs were takeu and include the period of incubation. This is done on account 

 of the confusion arisinjs in counting the age from the time of hatching, due to the variable length of the incubation period, which is 

 dependent upon temperature. 



