Nebraskaland

50 Nebraskaland • November 2024 While some of the eggs used at Rock Creek are obtained from federal hatcheries and fertilized before being shipped, quite often biologists, with a squeeze from their hands, start the process of making trout. Once a female's eggs are stripped, a male's milt is immediately put into the pan of eggs to fertilize them. This is a tedious task and must be done quickly as the eggs are full of pores and, once exposed to water and air, will begin closing rapidly. The milt must be obtained and enter the egg's pores quickly to fertilize them. After being fertilized, the eggs are placed in a large container with running water for three to four hours to harden. Afterward, they are moved into the hatching troughs in the hatch house. The already fertilized eggs that are delivered to the hatchery are shipped in ice water. Before these eggs can be placed in hatching troughs, the eggs are tempered by slowly warming the water they are in for three or four hours to match the temperature of the water in the troughs. Once in the troughs, temperatures have to be regulated as warm water speeds up the hatching process, which produces weaker fish and could lead to death. Successful temperatures are between 50 and 60 degrees for trout, and the spring-fed water from Rock Creek is about 56 degrees year-round. Newly hatched trout absorb their yolk sac as food, and once the sac is gone — around 14 days — trout look for other food swimming toward the surface of the water. Because of this, staff feed them ground liver four or five times daily. As the fry grow, they are thinned out to make room for slower-growing trout. Once trout reached a fingerling size of 1 to 2 inches, they are transferred to outdoor circular ponds. At this point, food is changed from a liver diet to a liver-cereal mix. The cereal is prepared by feed mills and is high in protein and vitamins. As the trout grow, they are again sorted with the larger fish placed in spring-fed ponds while smaller trout are held in the circular ponds. The sorting process is repeated until the fish are at a desirable length for pond stocking. Once in the pond, trout are fed only twice per day for two weeks before feeding is cut to once a day. Trout also feed on insect life naturally produced in the ponds. Surface feeding for insects prepares the trout for introduction into rivers, streams and lakes where they must feed on their own for survival. Making Trout Female rainbow trout eggs are stripped into a pan and ready for the male fi sh's milt. ROCKY HOFFMANN, NEBRASKALAND A microscopic image of fertile eggs. The "eye" in each circle is a trout. ROCKY HOFFMANN, NEBRASKALAND Newly hatched trout still have their egg sacs that will feed them until they are larger. ROCKY HOFFMANN, NEBRASKALAND

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