TEE SACRAMENTO SALMON. 203 



The average size of the fry passing Balls Ferry January 30 was 

 1.51 inches, and of those passing Walnut Grove 34 days later 1.79 inches, 

 an increase of .28 of an inch. Those passing Balls Ferry February 18 

 were 1.48 inches long, and 34 days later at Walnut Grove 1.77 inches, 

 an increase of .29 inch. We have learned from other sources that the 

 fry increase in length about .30 inch a month, and .28 and .29 inch in 

 34 days is not far from that rate. 



It seems, therefore, both from the size and number taken at the two 

 stations, that fry are about 34 days in passing from the upper to the 

 lower station. The distance between the two stations is about 350 

 miles, as the river winds, and their average daily progress is therefore 

 about 10 miles a day. 



An object floating with the current would make the distance between 

 the stations in less than 10 days, and if fry traveled only at night and 

 merely kept with the current, they would be only 18 or 20 days on the 

 way. It is probable that fry in migrating drift down stream tail first, 

 keeping the head up stream for ease in breathing, as well as for con- 



Walnut Grove Tkap. 



venience in catching food. In this way they would drift more slowly 

 than the current. I have seen fry at Battle Creek fishery traveling 

 with the current, and always with the head up stream, unless 

 frightened. The later and larger specimens found at Walnut Grove had 

 simply been longer on the road. The larger they became the more 

 slowly they drifted. Without doubt there are a few passing down the 

 river all summer, though we have been unable to find any after June. 



Much seining was done along the shores of Suisun, San Pablo 

 and San Francisco bays, and in Tomales Bay, to determine something 

 of the fry in brackish and salt water. Very few specimens were 

 taken, probably not over 50. The smallest specimens taken in San 

 Pablo Bay were 2.4 inches long, which indicates an age of about 414 

 months, and a period of three months for the migration. 



A net stretched across the mouth of Olema Creek, emptying into 



