PACIFIC SALMON FISHERIES. 207 
injury whatever from heing packed together in this manner, the water being supplied 
in a way that forces it through the eggs, partially supporting and circulating through 
them. The meshes are too small to permit the eggs to pass through, although the fry 
are able to do so. 
The advantages of this apparatus and method are: 
(1) The top of the tray or basket is out of the water and always entirely dry; con- 
sequently in handling it the hands are kept dry. 
(2) By tilting one end of the tray up or down a little or by lifting it entirely and 
settling it gently back again in its place the bad eggs will be forced to the top; thusa 
feather is not required in picking over the eggs and the injuries very often inflicted 
with it are avoided. 
(3) The top of the tray being above water, the eggs can never run over the top nor 
escape in any way, which is a great advantage over the shallow form of tray. 
(4) There is economy of space; 30,000 to 40,000 eggs can be placed in each basket, 
rovided a suflicient quantity of water is available. ‘Two troughs 16 feet long and 1 
oot wide will by this method carry about 500,000 salmon eggs. The deep trays may 
be filled at least half full of eggs, and thus 10 times as many eggs can be hatched in 
the same space and with the same supply of water as by the old method. A good but 
gentle circulation is continually maintained through the eggs. 
(5) The deep-tray system is admirably adapted to getting rid of mud that has col- 
lected on the eggs, for all sediment accumulating about them can be easily removed 
by gently moving the tray up and down a few times in the water; but if the deposit of 
mud on the troughs becomes so excessive as to be unmanageable, a false bottom of 
wire cloth or perforated zinc can be placed in the troughs at a suitable distance above 
their real bottom, leaving a space of about 1 or 14 inches between the wire cloth and 
the trough bottom. By this means the mud that comes into the trough will sift down 
into the space below the wire cloth entirely out of the way of the fish, the movements 
of the fish themselves helping very much to produce this result. Should the accu- 
mulation of mud in the space below the false bottom of the trough become too great, 
it can easily be sluiced out in various ways. 
When quinnat salmon eggs are simply to be matured for shipment, hatching trays 
with one-fourth or one-fifth inch square mesh will answer the purpose, but when the 
eggs are to be hatched in them, every alternate strand of wire running lengthwise, 
or, better still, every second and third thread, should be left out in order to form an 
oblong mesh through which the newly hatched fry, after separating themselves from 
the unhatched eggs, can escape from the hatching trays into the trough below. 
At Baird eggs kept in water averaging about 54° F. hatch in 35 days. The allowance 
of 5 days’ difference in the time of hatching for each degree of change in the water 
temperature is approximately correct. 
For the first few days the eggs of the quinnat salmon are very hardy, and at this 
time they should be thoroughly picked over and the dead ones removed as far as 
possible before the delicate stage during the formation of the spinal column comes on, 
so that during that critical period they may be left in perfect quiet. As soon as the 
spinal column and the head show plainly, the eggs are hardy enough to ship, but when 
ere is time enough it is better to wait a day or two until the eye-spot is distinctly 
visible, after which time the eggs will stand handling and may be safely shipped if 
properly packed. 
HANDLING EGGS IN HATCHERY.¢ 
At some of the Bureau’s stations where salmon eggs are handled it was the custom 
until a few years ago to “‘bury”’ the eggs or leave them undisturbed (aside from picking 
once the day after spawning) for two or three weeks after putting them in the baskets, 
The result was that they were in some instances literally buried under and in such a 
mass of mud and sediment that many eggs were killed. Discontinuance of the prac- 
tice resulted in a very appreciable improvement. 
When the water is so turbid as to cause a heavy deposit of sediment, it is better to 
go over the eggs occasionally, even through the critical stages of development, or 
until the line of the fish is well formed. Of course the eggs must be handled with 
utmost caution at all times, but owing to their extreme sensitiveness during the two 
or three days following the closing of the blastopore and until a perceptible curve 
shows in the tail, they should be left entirely untouched. It soon becomes easy to 
determine the stage of an egg’s development by holding it up to the light between the 
thumb and forefinger. In the absence of cautious and skilled operatives and unless 
the water is roily for an extended period, it is undoubtedly better to let the eggs 
a Fish Culture in Alaska, by Ward T. Bower. Jn Alaska Fisheries and Fur Industries in 1911. U.S. 
Bureau of Fisheries Document No. 766, pp. 81, 82. Washington, 1912. 
