86 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
THE FRY. 
NOTES ON YOUNGER FRY. 
Planting fry from the hatchery . — Fry are transported from the hatchery to the 
streams in the same manner as already described for alevins, but it is not practicable 
to carry over 10,000 in a can, even for a short distance. They require more care 
than alevins, it being necessary to aerate the water constantly. 
When fry are liberated in running water, they immediately head upstream and 
try to stem the current. Owing to their being more or less faint from confinement 
in t he can the current nearly always carries them downstream a short distance, but 
they soon find their way into the more quiet water along the edge of the stream, in 
the eddies or quiet pools, or among the stones at the bottom. Some even move a 
few yards above the place of planting before they come to rest. On gaining quieter 
water they rest themselves, moving only enough to keep from drifting downstream. 
When in such position they begin feeding on any particles of food that float within 
their vision, often snapping viciously at insects half as large as themselves. 
In a small stream there is no marked tendency of the fry to form schools, each 
appearing to act independently; but in a larger stream, and especially in the large 
pools, they often swim about in schools. It appears, too, from our observations 
in the Sacramento, that they run in schools after gaining the main river in their 
migration to the sea. 
After planting, the fry soon begin to drift downstream from one resting-place 
to another. This movement in small streams is not in schools. If many are planted 
at one place the movement downstream is quite rapid, and within 24 hours they will 
be scattered evenly along the stream for over a mile below the place of planting. 
The movement, though marked in the daytime, is more general at night. In one 
instance a sci-een was placed across a small stream a quarter of a mile below where 
50,000 fry were released. Although but few reached the screen that day, the 
following morning apparently every one had reached it. Other observations have 
shown the same thing. Muddy water hastens the movement downstream, as does 
also high water, which is usually muddy. 
In Hatchery Creek, in Marin County, 150,000 fry 10 weeks old were released. 
They gradually scattered downstream, floating tail first. In four or five days they 
were about evenly distributed along the creek for 14 miles below the hatchery. At 
the end of this time a net with a 10-incli circular mouth was placed' in the current 
in the daytime with mouth upstream. In one hour 30 or 40 fry were caught. This 
illustrates well the decided movement downstream after planting. 
When released in a large pool or pond the fry collect in schools immediately 
and travel toward the inlet. 
In 1898, 150,000 alevins were placed in a pond at the Bear Valley hatchery. 
These remained in the pond without being fed until four weeks after the absorption 
of the yolk-sac. As it had but 600 square feet of surface and was only 2 or 3 feet 
deep, there were obviously too many in the pond to do well without being fed. As 
would be expected, they grew but little, though few, if any, died. At the end of 
four weeks all were very nearly of one size — 1.4 inches long. Those of the same 
age in the creek a mile below the pond varied from 1.5 to 1.9 inches; specimens 
from Olema Creek only two weeks older were from 2 to 2.4 inches long. 
