SEAWARD MIGRATION OP CHINOOK SALMON. 



49 



This is shown by the close correspondence in estimated size of the yearUngs at the timie 

 of beginning the more rapid growth of the second year. This correspondence also 

 indicates that the yearlings migrating in the spring are a homogeneous lot and that the 

 check preceding the intermediate growth (in Groups i and 2) is the same as that pre- 

 ceding the new growth (in Group 4) ; that is, that this check in both instances is in reality 

 the winter band. (See discussion on p. 57.) The mode at 100 mm. undoubtedly repre- 

 sents, in the fall migrants, the size at the time of entering the estuary. It is possible 

 that these differences in the estimated size at which the intermediate growth begins may 

 be of value in determining, from the adult scales, the time at which migration took place. 



130 



Ix 



June July Aug. Sept. Oct. Nov. De 



Mqu Jun 



Jan. Feb. Mch. Apr. 

 rj^ Year Unga. 



Graph 2. — Estimated length at time of beginning intennediate growth (groups i, 2, and 

 3) and new growth (group 4). Figures at left of graph indicate length of fish in mm.; a, 

 group i; b, group 2; c, group 3; d, group 4; c, creek at Seufert, Oreg.; /, McKenzie River; 

 and solid line, growth curve for group i (from fig. i). 



The rate of growth of the migrating fry in the Sacramento River is given in Table 47 

 and is shown in graph 3. 



Table 47. — Migrating Fry from Sacramento River. 



