40 



BULLETIN OF THE BUREAU OK FISHERIES. 



Tabie 40. — Young Chinooks from McCloud River, Baird, Calif., Dec. 18, 1911 — Continued. 



FIFTY-ONE SPECIMENS WITH NEW GROWTH. 



Length. 



Scale record. 



Average number of 

 rings — 



To new 

 growth. 



Of new 

 growth. 



Average length of 

 anterior radius — 



To new 

 growth. 



Total. 



Average 



estimated 



length of 



fish at 



time of 



beginning 



new 



growth. 



ti6 to 130 mm, . 

 Ill to us mm. . 

 J06 to no mm. 

 loi to 105 mm. . 

 96 to 100 mm. . . 

 91 to 95 mm. . . , 



Av. 101.7 mm . 



13.0 

 U.6 

 14.4 

 13.6 

 13-3 

 12.4 



33.0 

 47. I 

 43- 7 

 42. o 

 40. 6 

 36.8 



49.0 

 S3, b 

 SO. 6 

 48.3 

 47.4 

 44. s 



98.0 

 96.3 

 91. o 

 88. s 

 81. 2 

 79-0 



13-4 



January 22, 1912, 75 specimens were collected. There were no mature males 

 among them. One of the males, however, was of unusual size, 142 mm., and the testes 

 of this specimen were found, upon dissection, to be slightly enlarged. It is shown later 

 (p. 68) that precociously matured males may recover from the effects of ripening the sex 

 products, and there is no doubt that this has occurred in the individual in question. No 

 new growth is recorded on the scales, the terminal rings being of the winter type. The 

 large size, enlarged testes, and delayed new growth all point to the interpretation given. 

 The scales indicate clearly that the fish was a yearling, the same age as the other speci- 

 mens. They show 20 rings, and the anterior radius measures 75 on the arbitrary scale. 

 This specimen is not included in the tables. Forty-three (58 per cent) of the other 

 specimens had begun the new growth. Thirty-one males average 104. i mm. in length 

 and 43 females 102.3 ™ni- The table (41) follows: 



Table 41. — Young Chinooks from McCloud River, Baird, Calif., Jan. 22, 1912. 

 thirty-one specimens without new growth. 



