Publications

THE year 1941 was a crucial one for the blueback salmon of the Columbia River. During that year, one brood came closer to extinction than was realized by more than a few individuals. The immediate causes were not overfishing, hydroelectric power development, or irrigation—although these factors continued to exert their long-standing effects. The direct causes can be attributed to an “act of God” p

The construction or Grand Coulee Dam, on the upper Columbia River, involved the loss of 1,140 lineal miles of spawning and rearing stream to the production of anadromous fishes. The fact that the annual value of these fish runs to the nation was estimated at $250,000 justified reasonable expenditures to assure their perpetuation. It was found economically infeasible to safely collect and pass adul

The water system at the U. S. Fish Cultural Station, Leavenworth, Washington, has been supplemented with two wells that were to be used to increase the temperature of the water during the winter and to cool the Water in the summer if necessary. The well water proved to be unsuitable for hatchery purposes because it was supersaturated with nitrogen, causing "gas-bubble" disease among fish subjected

A direct method for controlling diseases among hatchery fish has long been sought as an alternative to the earlier technique of hand dipping.  A  simple, practical, effective method of direct pond treatment not only obviates all need for handling fish weakened by disease, but it would materially reduce the time and effort required by hatcherymen in keeping diseases under control. Furthermore, a di

A natural outbreak of columnaris disease among wild adult and hatchery-reared fingerling salmon in the State of Washington is described. The disease is identified by the recovery of the causative organism, Bacillus columnaris Davis, which may be readily identified by its characteristic action in forming columns on the surfaces of infected material held in a water mount on a microscope slide. The g

A practical and economical method for anaesthetizing adult salmon and steelhead trout in the fish trucks used in the Grand Coulee fish salvage program is described. The method consists in generating a predetermined carbon-dioxide concentration in the 1000-gallon tanks of the trucks through the successive addition of predissolved sodium bicarbonate and dilute sulphuric acid in proper quantities. Ca

Costiasis, or the disease produced by the flagellated protozoan ectoparasite, Costia necatrix, is of considerable importance in the artificial propagation of both warm- and cold-water fishes. In spite of its importance, costiasis seldom is accurately diagnosed probably because of the extremely small size and sedentary nature of the causative organism. A general resume of the specific diagnostic ch

In a search for more effective disinfectants to combat parasitic diseases of hatchery fish, the authors report results from a series of experiments designed to determine the toxicity of varying exposures to concentrations of formalin, sodium p‐phenolsulphonate, ammonium sulphate, and sodium benzoate. Non‐toxic concentrations of these disinfectants were tested, in addition to the usual hatchery met

In an evaluation of the efficiency of trout culture, the author presents a detailed analysis of complete loss records from 288 individual lots of trout at twenty-two hatcheries in the western United States. Summarized data are given to show the percentage loss of eggs, fry, and fingerlings by progressive one-half inch size groups. The accumulative percentage loss is also included to indicate the l

After the completion of the eхреriments reported recently, in which the efficacy of formalin in controlling infections of Gostia mecatrix was demonstrated, the author was afforded an opportunity to test the value of formalin solutions in combatting established mixed infections of (Gyrodactylus, Tricbodina, Cyclochaeta) and a stalked protozoan on rainbow trout fingerlings. This opportunity was prov

No parasite common to hatchery salmon and trout possesses quite so varied a reputation as does Octomitus salmonis. Discovered, studied, and described independently, but essentially simultaneously, by Dr. Emmeline Moore and Dr. H. S. Davis, Octomitus salmonis was introduced to fish culture during the early twenties. This easily found and widely distributed parasite, once recognized, was soon held r

The smallest and most destructive of the ectoparasitic protozoans infecting salmon and trout, Costia necatrix, has unfortunately been relegated to virtual obscurity during the past few years. Few references to this parasite can be found in the recent literature and, where such things are discussed, one seldom hears a mention of Costia necatrix. This apparent lack of interest in Costia certainly do