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At least 37 records · Page 2Linked to original sources
USGS1970

Retention of mercury by salmon

Consuming fish that have been exposed repeatedly to mercury derivatives is a potential public health hazard because fish can accumulate and retain mercury in their tissues (Rucker, 1968). Concern has been expressed in the United States because mercurials have been used extensively in industry and as prophylactic and therapeutic agents in fish hatcheries. Rucker and Amend (1969) showed that yearling rainbow trout (Salmo gairdneri) and chinook salmon (Oncorhynchus tshawytscha) exposed to mercurials accumulated excessive amounts of mercury in many tissues. Further, Rucker and Amend (1969) concluded that wild fish that ate mercury-contaminated fish also could contain high mercury levels. Although mercury was eliminated from most tissues within several months, substantial levels remained in the kidney for more than 33 weeks after the last exposure. Since high levels of mercury can be retained in the kidney for an undetermined time, it is possible that returning adult salmon exposed to mercurials as juveniles could constitute a potential hazard to public health. The purpose of this study was to determine whether such fish contained high residual levels of mercury.

Progressive Fish-Culturist↗
USGS1970

Experimental control of Columnaris sisease with a new Nitrofuran drug, P-7138

P-7138 is a new, broad-spectrum, vinylogous, nitrofuran chemotherapeutic that was developed specifically for treating fish diseases. Although it can be added to the diet of fish, therapeutic tissue levels can be obtained in eels (Anguilla japonica) and goldfish (Carassius auratur) by absorption of the drug directly from the water. Moreover, the drug is eliminated from the tissues within hours and shows a low level of toxicity (Shimizu and Takase 1967). The purpose of the present study was to deterime 910 the efficacy of P-7138 in controlling an experimentally induced Chrondrococcus columnaris infection, 920 the absorption and elimination rates, and 930 the degree of acute and chronic toxicity to coho salmon (Oncorhynchus kitutch).

Progressive Fish-Culturist↗
USGS1970

An obscure disease of rainbow trout

An annul mortality among Rainbow Trout (Salmo gairdneri) has plagued the Shelton Hatchery of the Washington State Department of Game for the last several years. No infectious agent could be isolated from the moribund fish, but histopathologica1 changes in the liver of 1-month-old fish suggested the presence of a toxic substance. Scoliosis in 3-month-old fish suggested a possible deficiency in vitamin C. With this background in mind, we designed studies to determine the nature and source of possible toxicants and the role of vitamin C deficiency in the etiology of this disease.

Progressive Fish-Culturist↗
USGS1971

A procedure for testing the antigenicity of vaccines for immunization of fish against Furunculosis

Furnunculosis, a bacterial disease caused by Aeromonas salmonicida, is potentially one of the most devastating diseases in trout and salmon hatcheries. The disease may be controlled by three methods. The most frequently used method of control has been drug therapy. Unfortunately, the bacteria often develop resistance to the specific antibacterial drug. For example, sulfamerazine has been used widely to control furunculosis as well as other diseases. With repeated use in a population of fish, however, the bacteria soon develop resistance to the drug, thus rendering it ineffective in controlling the disease. In addition, drug therapy usually provides only temporary control and recurrences of the diseaseare very common.

Progressive Fish-Culturist↗
USGS1972

Survey for infectious hematopoietic necrosis (IHN) virus in Washington salmon

A virus disease of juvenile sockeye salmon ( Oncorhynchus nerka ) has been a problem in Washington hatcheries since first reported by Rucker [9] in 1953. Presumably, the same disease has occurred in Oregon, and it is now referred to as the Oregon, and it is now referred to as the Oregon sockeye disease (OSD) or the sockeye salmon virus (SSV) [8,12]. The primary source of the disease was thought to be from the feeding of raw sockeye salmon viscera, and the incidence decreased when pasteurized diets were used [5]. However, sporadic attacks continue to occur even though pelleted diets containing pasteurized fish products are fed.

Progressive Fish-Culturist↗
USGS1972

Feeding behavior of lake whitefish and lake herring in Torch Lake, Michigan

It is proposed that Haemoproteus nettionis (Johnston and Cleland, 1909) Coatney, 1936 be accepted as the correct name for the Haemoproteus of Anatidae. A list of synonyms and amended description of the parasite is given. Infections are reported from wood ducks (Aix sponsa) and from domestic ducks and geese, the last representing a new host record. Natural transmission was demonstrated at the Patuxent Research Refuge, Laurel, Maryland. Possible seasonal variation is suggested with active carriers present as early as mid-April among adult wood ducks and most active transmission occurring in June and early July with limited transmission earlier or later.

Progressive Fish-Culturist↗
USGS1984

Determining fat digestibility in trout using a metabolic chamber

Fat digestibilities were determined in rainbow trout utilizing a metabolism chamber. Separate and quantitative fecal extracts were freeze dried and total lipids were extracted. Lipid digestibilities were comparable to those obtained by other methods (85‐91%). This method avoids problems due to leaching and the variable of accelerated passage through the gut encountered in other methods.

Progressive Fish-Culturist↗