Hatchery Process

by Fly Fisherman

During the growth of the various divisions of the trout there is activity in thinning out the numbers, grading them and removing individual fish for sampling and laboratory study. This practice has been found to lessen the frequency of disease, the reducing of cannibalism and, of importance to a busy hatchery, the satisfying result of more rapid growth and a high percentage decrease in runty and poor quality fishes. This grading and thinning begins at about the two- to three-inch length stage of our trout.

Another big and significant activity, that is religiously performed by the modern hatchery, is the judicious, selective breeding of the trout. The objective, initially, is for improvement of the fish crop produced. The factors that are desired are those possessed by the wild trout, in many instances, and a plus not held, particularly, by those stream born fish. What is most desired of the trout, which will be planted in our fishing waters, is first, the ability to forage for himself, find his own food, to have a resistance to parasites and fish diseases, a vigorous “aliveness,” ability to reproduce the species in the natural environment, to be fast growing, have good color and top physical and symmetrical characteristics. The speedy growth and disease resistant traits are those most sought from the hatchery procedure angle. The foraging ability and aliveness are best from the survival standpoint and every one of the attributes is desired by ourselves, as fishermen.

We will presume, now, that our trout has reached the required size mark and is scheduled for depositing in some stream or lake. The hatchery discontinued the feeding, of this batch, for from twenty-four to forty-eight hours prior to the time that the trout will be taken from his pond. They have been counted, graded and weighed some time before this transfer. The fish are netted and shifted to the tank, or cans, that have been prepared. If by truck, they are started on their way at once. Reaching the plant point, temperature of the water is or should be taken where the fish are to go. If too much difference is noted, water from the receiving site is gradually put in the containers until the carrying water agrees with that in which the trout are to be placed and the plant is made.

One of the major problems confronting the hatchery is that of diseases, fungus and parasites afflicting their fish stock. In
many cases, with even as low a creature as the fish, many of the diseases, to which they are subject, have a similarity to the afflictions of man. Look at these: anemia, ulcers, cirrhosis of the liver, kidney diseases, gastric and gas disorders and dropsy. Besides that catalog the trout have to contend with fungus, worms, internal and external parasites, furunculosis, gill diseases, fin rot, trichodina and a form of virus diseases. Can you realize now the care that must be exercised in the sterilization of troughs, tanks and ponds and the cleanliness that has to be observed at every turn? Improper diet can cause some disruption but many of the ills are of a contagious nature and every precaution is taken against the spread should there be a break out of one. Disinfection must follow wherever there has been even minor cases of virus attacks or communicable maladies of any sort.

There are hatchery operatives who are skilled in diagnosis of the above diseases and from that determination can prescribe medicines and chemicals to counteract or cure. For instance, they know that glacial acetic acid, and formalin, will attack parasites, that malachite green is a remedy for fungus on both fish and eggs, that common salt is good for external infections. In addition to those chemicals they use calomel, merthiolate and sulfo-merthiolate, terramycin and much study is being made on the uses of other antibiotics in the treatment of fish disorders.

The hatchery also must constantly fight many other enemies of their precious babies. Birds, mammals, reptiles, certain insects, even vegetation is a problem. In their ponds they battle the submerged plant growth, also the emergent vegetation from water cress to cattails. They know that drying and working a pond helps much in the control of aquatic vegetation, that cutting of emergents below the water surface, plus a natural, or forced, bloom is effective in control. They know that poisons, traps and shotguns are necessary implements for eradication. They know that silt can be controlled or the condition improved by the application of hay, grass or manure directly on the water. Insects, such as water boatmen, back swimmers, dragonfly nymphs and diving beetles are a troublesome plague that needs be fought in every reasonable way.

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