94 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
2. 'I’he height of migration was from March 4 to about the 24th, about 20 days. 
3. On March 8 and 20 there were two large runs of fry. 
4. Practically all had passed by the 22d of April. 
5. The average size of those taken during January was 1.6 inches, during 
February 1.8 inches, during March 1.7 inches. From the 30th of March till May 7 
the size gradually increased from 1.7 inches to 3 inches. 
6. No fry were taken during the first 9 days in January. 
7. Young salmon traveled as much during the day as during the night. 
Comparing the information for Walnut Grove with that for Balls Ferry, as 
shown in the accompanying diagrams, plate 12, it appears that — 
(a) The Balls Ferry run of February 2 reached Walnut Grove March 8 and was 
34 days making the distance. The fry increased in size 0.3 inch. 
(b) The Balls Ferry run of February 14 reached Walnut Grove March 20, and 
was 34 days making the distance. The fry increased in size 0.3 inch.. 
(c) The runs that passed Balls Ferry February 25, and later, were caught by 
high water the latter part of March, which probably carried them down faster. The 
runs were not noticed at Walnut Grove; the net could not lie worked during the 
beginning of high water, March 23 to 29, during which time they may have passed. 
(d) The fry taken at Walnut Grove after April 1 had grown more than 0.3 inch 
since starting downstream, and were therefore the stragglers from the regular 
migration. Those taken during May had probably been three months on the way. 
It is evident, therefore, that the fry of the regular migration require about 34 
days to pass from Balls Ferry to Walnut Grove. 
The distance between the two stations is about 350 miles. An object floating 
as fast as the current would make the distance in about 9 days. It requires 8 days 
for a rise in the river to travel from Red Bluff to Sacramento. If the fry traveled 
only at night, and simply kept with the current, they would make the distance in 
18 days. There is no doubt that in migrating the fry drift downstream tail first, 
keeping the head upstream for ease in breathing as well as for convenience in catch- 
ing food floating in the water. In this way they would drift much more slowly than 
the current. At Battle Creek hatchery fry have been observed traveling with the 
current, and always with the head upstream unless frightened. 
The later and larger specimens found had simply been longer on the way. The 
larger they became the more slowly they drifted, as they swam against the current 
more strongly. Those taken at Walnut Grove in January were but 1,6 inches long, 
being brought down by the high water in January, the short time they had traveled 
being indicated by their smaller size. 
The failure to catch any fry during the first 9 days in January indicates that the 
fry from the summer run had all passed and that those from the fall run had not 
yet reached Walnut Grove. Without doubt there were a few passing at that time, 
for there were some passing Battle Creek as late as December 6, but they were so few 
that none, were taken in the trap. It is possible that there are a few passing down 
the river all summer, though we have been unable to find any after June. 
Observations at Benicia . — February 21 and 24 and March 3, 1899, five specimens 
1.8 to 1.9 inches long were taken in Carquinez Straits at Benicia. The average size 
at Walnut Grove after February 10 was 1.8 inches and the size of the Benicia speci- 
mens indicates a short passage between the two places, probably not over a week. 
This would make the time from Battle Creek hatchery to brackish water 6 weeks. 
