Myxosoma cerebralis: Inactivation of Spores by Hot Smoking of Infected Trout

1982 ◽  
Vol 39 (6) ◽  
pp. 926-928 ◽  
Author(s):  
Ken Wolf ◽  
Maria E. Markiw
Keyword(s):  
Rainbow Trout ◽  
Aquatic Environment ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Soil Samples ◽  
Healthy Tissue ◽  
Salmo Gairdneri ◽  
Heat Inactivation ◽  
Whirling Disease

We processed 2-yr-old rainbow trout (Salmo gairdneri) and brook trout (Salvelinus fontinalis) with clinical whirling disease, which is caused by Myxosoma cerebralis, in one of the following ways: iced, iced and brined, or iced, brined, and hot smoked at 66 °C for 40 min. Skeletal elements of each group were added to tanks containing soil samples from an aquatic environment free of M. cerebralis and aged for 4 mo at 12.5 °C. Following this we assayed for infectivity by holding susceptible rainbow trout fry for 3 mo in the tanks of aquatic soil and skeletal elements. The fry were then examined for M. cerebralis spores. Spores were found in the fry from tanks that had received iced and iced and brined samples, but not in fry from the tanks containing hot smoked tissue, healthy tissue, or no tissue — the last two being negative controls.Key words: whirling disease, Myxosoma cerebralis, heat inactivation, hot smoking

Food Specialization By Individual Trout

1972 ◽  
Vol 29 (11) ◽  
pp. 1615-1624 ◽  
Author(s):  
James E. Bryan ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Potential Prey ◽  
Repeated Observation ◽  
Size Growth ◽  
Salmo Clarki

Analyses of stomach contents showed that the kinds of prey eaten by brook trout (Salvelinus fontinalis), cutthroat trout (Salmo clarki), and rainbow trout (Salmo gairdneri) were seldom distributed at random among the individuals. Repeated observation of food eaten by individuals in a stream and ponds showed that prey types were eaten in proportions which were characteristic for an individual.Specialization occurred on several different kinds of prey. Although the degree of specialization was higher during shorter intervals, the data suggested that some specialization persisted for half a year. There were no striking correlations between degree of specialization and other individual properties such as size, growth rate, weight of food, number of food items, previous specialization, or area of recapture.In addition to the observations on trout in relatively undisturbed habitats, a field experiment was conducted using laboratory-reared rainbow trout held in small ponds. The food of each trout in the experiment was sampled repeatedly. In analysis of variance, interaction among the individuals and kinds of prey eaten showed that food specialization occurred. Both the absolute and relative abundance of potential prey were constant during the experiment.

Aeromonas salmonicida: Relationship between Extracellular Growth Products and Isolate Virulence

1981 ◽  
Vol 38 (11) ◽  
pp. 1322-1326 ◽  
Author(s):  
Rocco C. Cipriano ◽  
Billy R. Griffin ◽  
Burton C. Lidgerding
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Aeromonas Salmonicida ◽  
Salmo Gairdneri ◽  
Lesion Development ◽  
Culture Supernatants ◽  
Crude Material

Extracellular growth products, extracted from culture supernatants of Aeromonas salmonicida by precipitation with ammonium sulfate and ethanol, were resolved into four fractions by ion-exchange chromatography. Although one of these (fraction II) possessed leukocytolytic activity, virulence of the pathogen was not associated with leukocytotoxicity. A positive correlation was established, however, between virulence and the toxicity of extracted material to cultured rainbow trout gonad (RTG-2) cells. The crude material and fractions II and III from virulent isolates were more toxic to RTG-2 cells than were similar preparations from avirulent isolates. Preparations from virulent isolates caused hemorrhaging, lesion development, and mortality when injected intramuscularly into brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo solar). Rainbow trout (Salmo gairdneri) were more resistant and lesions could be produced only with fraction II. Fraction II also possessed proteolytic activity.Key words: Aeromonas salmonicida, furunculosis, pathogenicity, salmonids, extracellular products, cytotoxicity, leukocytolysis, proteolysis, fishes

Models of Ammonia Excretion for Brook Trout (Salvelinus fontinalis) and Rainbow Trout (Salmo gairdneri)

1980 ◽  
Vol 37 (9) ◽  
pp. 1421-1425 ◽  
Author(s):  
Larry J. Paulson
Keyword(s):  
Body Weight ◽  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ammonia Excretion ◽  
Salmo Gairdneri ◽  
Feeding Rates ◽  
Data Set ◽  
Nitrogen Consumption ◽  
Good Agreement

Ammonia excretion by brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) was measured in relation to nitrogen consumption, body weight (15–154 g for rainbow trout and 50–360 g for brook trout), and temperature (11.2–21.0 °C) under laboratory conditions. Four natural diets, collected from Castle Lake, California, and a commercial pellet diet were fed to the trout in gelatin capsules at feeding rates from 2.5 to 5% body weight∙d−1. Nitrogen consumption was the most important factor influencing ammonia excretion, followed by body weight and temperature. Testing the models with an independent data set revealed good agreement between measured and predicted rates of excretion. The models seem to estimate adequately ammonia excretion by trout in both natural and artificial aquatic systems.Key words: models, ammonia excretion, nitrogen consumption, body weight, temperature, multiple regression, rainbow trout, brook trout

Isolation of Infectious Pancreatic Necrosis Virus from the Blood and Blood Components of Experimentally Infected Trout

1982 ◽  
Vol 39 (1) ◽  
pp. 225-228 ◽  
Author(s):  
Robert N. Swanson ◽  
James H. Gillespie
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Pancreatic Necrosis ◽  
Salvelinus Fontinalis ◽  
Infectious Pancreatic Necrosis Virus ◽  
Salmo Gairdneri ◽  
Blood Components ◽  
Necrosis Virus ◽  
Infectious Pancreatic Necrosis ◽  
Pancreatic Necrosis Virus

Experimental infection with infectious pancreatic necrosis virus (IPNV) was achieved in yearling rainbow trout (Salmo gairdneri) and 7-mo-old brook trout (Salvelinus fontinalis) by intraperitoneal inoculation and by water contact, respectively. Blood removed periodically from both groups of fish was fractionated and various blood components examined for virus. IPNV was recovered consistently from the plasma and mononuclear-enriched blood fractions of the rainbow trout from 1 to 19 d postinoculation (DPI) and also was detected in the mononuclear fraction on 33 DPI. In the brook trout virus was recovered from 3 to 40 DPI in the plasma and from 7 to 40 DPI in the mononuclear fraction. Thus a viremia appeared to be important in the early stages of experimental IPNV infection and infectious virus was found both free in the plasma and in association with an undetermined cell population present in the mononuclear component of blood.Key words: infectious pancreatic necrosis, blood, fish disease, Salmo gairdneri, Salvelinus fontinalis

Growth Decline in Subyearling Brook Trout (Salvelinus fontinalis) after Emergence of Rainbow Trout (Salmo gairdneri)

1986 ◽  
Vol 43 (1) ◽  
pp. 187-193 ◽  
Author(s):  
G. A. Rose
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Taxonomic Composition ◽  
Salmo Gairdneri ◽  
Mean Width ◽  
Growth Decline ◽  
Food Size ◽  
Competition For Food ◽  
Overwintering Mortality

In a tributary of Lake Superior, brook trout (Salvelinus fontinalis) subyearlings, after emergence in April, initially gained length at 0.51 mm/d and weight at a specific growth rate per day (G) of 0.058. After the emergence of larval rainbow trout (Salmo gairdneri) in June, however, length increments of brook trout declined to 0.05 mm/d and G was reduced to 0.005. During August, brook trout growth rebounded somewhat (0.12 mm/d; G = 0.008). Rainbow trout subyearlings, by contrast, grew at relatively constant rates of 0.42 mm/d and G of 0.040, from emergence until September. By late August, mean weights of brook and rainbow trout, 2026 and 2282 mg, respectively, did not differ significantly. Stream positions occupied by brook trout, characterized by flows of less than 20 cm/s and depths of less than 40 cm, did not change over the first summer. During June and July, stream positions of rainbow trout subyearlings coincided with those of brook trout. During August, however, rainbow trout moved to faster waters (>20 cm/s). The taxonomic composition of the diets of the two species did not differ. Mean width of food items consumed was linearly correlated with the total length of the fish (r = 0.97). The range of sizes of items eaten by the two species overlapped considerably by mid-June. For brook trout, mean food size increased, and amount consumed decreased, after the emergence of rainbow trout larvae. Growth reduction during the first summer, an outcome of interspecific competition for food and space, may result in increased overwintering mortality of fish at high latitudes, and be a mechanism by which brook trout are excluded by rainbow trout.

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