Zt U. S. BUREAU OF FISHERIES. 
pose of holding them during the feeding period, prevented the general 
adoption of the rearing system. 
For some years certain fish culturists and others had contended that 
the planting of fry just after they had absorbed the umbilical sac was 
an economic mistake, claiming that at this age they were weak and 
comparatively sluggish in their movements, and would fall easy prey 
to their numerous fish, bird, and other enemics. The late Robert D. 
Hume, who built and operated a hatchery on the lower Rogue River, 
also one on the upper Rogue River, which the United States Bureau 
of Fisheries operated for some years, was one of the first to take up 
the rearing of salmon fry on any scale. 
In time these objections bore weight, and a few years ago the con- 
struction of ponds in which fry could be held and fed until they had 
reached a size which would insure them at least an even chance for 
their lives was undertaken all along the coast except in British 
Columbia, with the result that to-day there is a pona capacity for 
about one-half of the total capacity of the various Matcheries 
Most of the nursery ponds have been constructed near the hatch- 
eries and usually comprise oblong trenches dug in the earth and walled 
with cement and stone. 
In Oregon the State authorities found that the best results in pond 
rearing were obtained by using creek or natural ponds, which were 
made i placing dams across the small streams in the vicinity of the 
hatcheries. When first taken from the hatching troughs the fry are 
placed in the artificial ponds until the danger from spring freshets in 
the small streams is over. They are then transferred to the natural 
ponds, where the continual flow of fresh water, and the logs, rocks, 
etc., which provide shade and shelter, afford more natural conditions, 
and in which the natural food of the fry supplements the artificial 
food provided by man. 
A big advantage in connection with the use of natural ponds is the 
comparatively small expense involved in providing for them as com- 
pared with the large expense involved in the construction of cement 
onds. 
i The young fry show when they are ready to feed by dar ing to one 
side or the other when small particles of food are dropped in the water 
and float past them. For the first few weeks they should be fed 
regularly and as often as six times a day, and the earlier in the day 
the feeding begins and the later it continues at night the better. 
Two hours after feeding they will be found to be ravenously hungry, 
and as they grow much faster for frequent feeding great care should 
be taken to see that they are well fed. If not fed sufficiently they 
will bite at one another and cause more or less mortality among 
themselves. 
FOOD. 
In feeding salmon fry almost every conceivable food has been 
utilized. By universal consent liver is conceded to be the best food 
for the fry, as it can be ground finer than other foods and the blood 
which it contains is highly nutritious. At many places, however, it 
is impossible to secure liver, while its cost when available is generally 
prohibitive. 
The food used is generally that most available and which experi- 
ence has shown that the fry like and upon which they thrive. 
