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COMBINING EGGS AND MILT 



TROUT EGGS 



and females — fish ready to spawn — simply drop 

 their milt and eggs together in the water. Here 

 we strip the ripe trout, that is, we take their eggs 

 and milt. Our spawntaker holds a ripe female 

 with the tail pointing downward over a moistened 

 pan, and gently presses the fish's belly with thumb 

 and forefinger until the eggs flow from the fish's 

 vent into the pan. A female trout may have sev- 

 eral thousand eggs. After stripping several fe- 

 males, the spawntaker selects a male and presses 

 it until enough milt has been deposited in the jjan 

 to fertilize the eggs. Then he stirs the eggs and 

 milt, adds a little water, shakes the pan gently, 

 and sets it aside for a short time to let the milt 

 fertilize them. Finally the spawntaker washes off 

 the excess milt and puts the mass of eggs in water 

 to harden. 



As soon as the eggs are water-hardened — that's 

 when they separate — we measure and count them, 

 and put them on wire-bottomed wooden trays. 

 We place these trays in the running water of the 

 troughs that you see here. We try not to disturb 

 the eggs until we see the small spots tliat will 

 later be the eyes of the fish. Then, because the 

 eyed eggs are less delicate, we can pick out any 

 dead (white) eggs that may be in the trays. 

 If the water temperature is around 45° F., rain- 

 bow-trout eggs usually hatch in about 4.5 days 

 and brown-trout eggs in about 63 days. 



Newly hatched fish are known as fry. Last 

 spring a very young visitor remarked that what 

 came from the egg looked more like a small gum- 

 drop with a head and a tail than it did like a fish. 

 What he called a gumdrop was the yolk sac which 

 is the fry's supply of food. As the fry gets older, 

 this sac becomes longer and slimmer until it dis- 



appears, and we have a young fish that can use its 

 fins and tail to swim about freely. 



For some weeks after hatching, a fry stays near 

 the bottom of the tray, held down by the weight of 

 its yolk sac. As the yolk sac gets smaller, the fry 

 becomes lighter in weight — and hungry — and rises 

 in the water. In a very short time all the fry 

 learn to feed on a daily ration of beef liver or 

 heart ground very fine and put through a hand 

 ricer with small holes. As the fry grow larger, 

 we supply this meat in larger pieces. When the 

 young fish have grown to fingerling size, perhaps 

 2 inches long, we move them to the raceways and 

 start feeding them a less expensive diet of mixed 

 dry foods and meat products. 



Salmon ? No, we don't have them here. Most 

 of the Federal hatcheries that have salmon are 

 on the West Coast, especially in the Columbia 

 River Basin of Washington and Oregon. You 

 see, the several species of Pacific salmon hatch 

 in streams that have coastal outlets. They mi- 

 grate down these streams to the ocean, where they 

 spend a year or moi'e before returning to inland 

 waters to spawn and die. 



If you should visit a salmon hatchej-y, you 

 would find that it uses cold water, holds its fish 

 in troughs and raceways, and feeds a carefully 

 prepared diet. The big difference between trout 

 and salmon hatcheries is that trout may be used 

 as brood or parent fish for several seasons, whereas 

 ripe Pacific salmon are killed for stripping of 

 eggs and milt since, even when free in the streams, 

 they all die after spawning. So few salmon are 

 able to spawn in the wild nowadays that taking 

 eggs and milt is the only way to be sure that the 

 eggs will have a chance to hatch, or that the fry 



