THE SACRAMENTO SALMON. 



20I 



Of the 339 young salmon taken in the trap, 322 were under 2 inches 

 long, and 17 over 4 inches. 178 of the smaller specimens were meas- 

 ured accurately with the following results : 



The smallest had just absorbed the yolk-sac, and in many there 

 was yet a small quantity of yolk remaining. Those 1.6 inches long had 

 not been feeding over three weeks, as other observations show that they 

 grow at the rate of .3 inch a month. That we found young salmon 

 that had barely absorbed the yolk-sac indicates that they begin their 

 migration as soon as they are able to swim. That they remained of 

 the same size from October 8 to November 30 indicates that prac- 

 tically all start down stream at the same age. If any of the same age 

 as those taken October 8 had been taken during the last days of 

 observation, the fact would have been indicated by their increased 

 size. In 53 days they would have grown over half an inch, and would 

 have been at least two inches long. There were no intermediate sizes 



between 1.8 inches and 4.0 inches. The larger individuals had 

 remained over from the previous year. The trap was so set that they 

 could not have avoided it during the day. The fact that none was 

 taken during the day indicates that they travel more or altogether at 

 night. The last record shows that 24 were taken from 8 to 9 a.m., 

 which is the only day record. This is accounted for by high and 

 muddy water, caused by a heavy rain during the previous night. This 

 and other observations indicate that high and muddy water, especially 

 the latter, is an incentive to day travel. 



The two months' observations with the trap at Battle Creek were 

 deemed of such importance that two observation stations were estab- 

 lished on the river the first of January, 1899, and equipped with similar 

 traps. The upper station was established at Balls Ferry, some three 

 miles above the mouth of Battle Creek; the other at Walnut Grove on 

 the lower river. The diagrams indicate the number of salmon fry 

 taken in the traps at the two stations : 



