Influence of water temperature on behavioural interactions between juvenile brook charr, Salvelinus fontinalis, and rainbow trout, Salmo gairdneri

1986 ◽  
Vol 64 (6) ◽  
pp. 1288-1291 ◽  
Author(s):  
Richard A. Cunjak ◽  
John M. Green
Keyword(s):  
Rainbow Trout ◽  
Competitive Advantage ◽  
Salvelinus Fontinalis ◽  
Salmo Gairdneri ◽  
Optimal Temperature ◽  
Brook Charr ◽  
Thermal Range ◽  
Influence Of Water ◽  
Behavioural Interactions ◽  
Brook Char

Interspecific behavioural interactions between paired brook char (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) were compared at different water temperatures to test the hypothesis that a species realizes a competitive advantage within its optimal thermal range. Three test temperatures were used: 19 °C (optimal temperature for rainbow trout), 13 °C (optimal temperature for brook charr), and 8 °C (below the optima for both species). Brook charr dominated rainbow trout at both 8 and 13 °C. At 19 °C, neither species displayed an obvious competitive advantage. The time (days) to the establishment of a dominance hierarchy reflected specific optimal temperatures; it was shortest for rainbow trout and brook charr at 19 and 13 °C, respectively. The implications of optimal temperatures and competitive ability are discussed in relation to habitat partitioning in the stream environment.

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

Natural anti-proteases in rainbow trout, Oncorhynchus mykiss and brook charr, Salvelinus fontinalis and the in vitro neutralization of fish α2-macroglobulin by the metalloprotease from the pathogenic haemoflagellate, Cryptobia salmositica

Parasitology ◽  
1997 ◽  
Vol 114 (4) ◽  
pp. 375-382 ◽  
Author(s):  
X. ZUO ◽  
P. T. K. WOO
Keyword(s):  
Rainbow Trout ◽  
Protease Inhibitor ◽  
Oncorhynchus Mykiss ◽  
Proteolytic Activity ◽  
Blood Cells ◽  
Salvelinus Fontinalis ◽  
Brook Charr ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Α2 Macroglobulin

Natural anti-proteases (α1-protease inhibitor (α1-PI; α1-antitrypsin) and α2-macroglobulin (α2-M)) were found in the blood of rainbow trout, Oncorhynchus mykiss and brook charr, Salvelinus fontinalis. The α2-M inhibited Cryptobia salmositica proteases and was significantly higher in brook charr than in rainbow trout. Under in vitro conditions it took longer for the same number of parasites to neutralize the α2-M in charr than in trout blood. The haemolysis which occurred when C. salmositica was incubated in the blood of rainbow trout was due to neutralization of α2-M. This in vitro study also showed that it was the metalloprotease of C. salmositica that lysed red blood cells and the plasma of the two species of fishes initially prevented haemolysis by inhibiting the proteolytic activity. We suggest that the natural plasma α2-M plays an important role in defence against cryptobiosis in fishes.

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

The response of stonefly (Plecoptera) nymphs to seasonal increases in predation risk

2002 ◽  
Vol 80 (6) ◽  
pp. 967-972 ◽  
Author(s):  
Nicole A McCutchen
Keyword(s):  
Rainbow Trout ◽  
Predation Risk ◽  
National Park ◽  
Salvelinus Fontinalis ◽  
Substrate Surface ◽  
Lake Outlet ◽  
Harlequin Ducks ◽  
Brook Char ◽  
A Site ◽  
Increases In Risk

The main objective of this study was to determine if predation risk accounted for the patterns of stonefly (Plecoptera) nymph abundance in the Maligne Valley watershed, Jasper National Park, Alberta. Seasonal declines in nymph density corresponded to increased use of the Maligne Lake Outlet and Lower Maligne River by harlequin ducks (Histrionicus histrionicus). Neither decline represented a shift from aperiodic to nocturnal use of surface rocks. Rather, rock use remained aperiodic throughout the season despite increases in risk. The decline that occurred in the Maligne Lake Outlet also did not represent a shift from small to large surface rocks. These results, when combined with the results of an odor experiment, suggest that nymphs tend to avoid surface rocks when in the presence of harlequin ducks. Nymph density did not decline seasonally in the Middle Maligne River, a site free of harlequin ducks but inhabited year-round by brook char (Salvelinus fontinalis) and rainbow trout (Onchorhynchus mykiss). Nymphs in this site as well as those exposed to char odor were nocturnally biased in their use of the substrate surface. Overall, predation risk appears to play a strong role in the patterns of stonefly nymph abundance in the Maligne Valley watershed, although not in the way originally expected.

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

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