Tests of Competition between Native and Introduced Salmonids in Streams: What Have We Learned?

1988 ◽  
Vol 45 (12) ◽  
pp. 2238-2246 ◽  
Author(s):  
Kurt D. Fausch
Keyword(s):  
Empirical Evidence ◽  
Brook Trout ◽  
Native Species ◽  
Salvelinus Fontinalis ◽  
Experimental Tests ◽  
Salmo Gairdneri ◽  
Review Of Literature ◽  
Inadequate Knowledge ◽  
Current Controversy ◽  
Stream Salmonids

Salmonids have been introduced worldwide to regions where they were not indigenous, usually without considering the effects on native species. This has led to many combinations of species in unnatural sympatry, some of which are suspected to interact strongly, but we currently have inadequate knowledge to allow us to predict the outcome of most such introductions. For example, despite current controversy about the potential effects of Pacific salmonids now stocked in Atlantic waters, we have only empirical evidence with which to judge whether they will be detrimental to Atlantic salmon (Salmo salar). Moreover, most experimental tests of interspecific competition between other pairs of stream salmonids have not been rigorous. A review of literature about the suspected competition between brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) in streams reveals that despite empirical evidence that water temperature and velocity play a critical interacting role in determining the outcome, most experiments have failed to elucidate the important mechanisms involved. Carefully designed experiments that compare the strength of interspecific versus intraspecific competition for different size classes will allow us to improve predictions about the effects of introduced salmonids on native species in streams.

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

Adjuvant-Dependent Immunity and the Agglutinin Response of Fishes Against Aeromonas salmonicida, Cause of Furunculosis

1985 ◽  
Vol 42 (7) ◽  
pp. 1290-1295 ◽  
Author(s):  
Rocco C. Cipriano ◽  
Stephen W. Pyle
Keyword(s):  
Salmo Salar ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Aeromonas Salmonicida ◽  
Salmo Gairdneri ◽  
Extracellular Product ◽  
Experimental Challenge

Adjuvant-dependent immunity resulted in agglutinin activity against Aeromonas salmonicida in sera of convalescent fishes. Rainbow trout (Salmo gairdneri), brown trout (Salmo salar), and brook trout (Salvelinus fontinalis) that had recovered from natural furunculosis produced serum agglutinin antibodies predominately against a specific chromatographic fraction (EcF1) of the bacterium's extracellular product. EcF1 was resolved by ion-exchange chromatography from DEAE SephadexA-25. When EcF1 was emulsified in Freund's incomplete adjuvant and injected intraperitoneally, brook trout were protected against experimental challenge; brook trout vaccinated with EcF1 only were not protected against furunculosis. EcF1, examined by immunodiffusion tests, SDS – polyacrylamide gel electrophoresis, and Western blot immunoassays, shared certain properties with bacterial endotoxin. EcF1 and endotoxin preparations both contained immunoreactive lipopolysaccharides which indicated that adjuvant-dependent immunity to A. salmonicida is related to endotoxin.

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

Have brook trout (Salvelinus fontinalis) displaced bull trout (Salvelinus confluentus) along longitudinal gradients in central Idaho streams?

2006 ◽  
Vol 63 (1) ◽  
pp. 63-78 ◽  
Author(s):  
Bruce E Rieman ◽  
James T Peterson ◽  
Deborah L Myers
Keyword(s):  
Regression Analysis ◽  
Brook Trout ◽  
Native Species ◽  
Salvelinus Fontinalis ◽  
Hierarchical Regression ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
Longitudinal Gradients ◽  
Local Extinctions ◽  
Central Idaho

Invasions of non-native brook trout (Salvelinus fontinalis) have the potential for upstream displacement or elimination of bull trout (Salvelinus confluentus) and other native species already threatened by habitat loss. We summarized the distribution and number of bull trout in samples from 12 streams with and without brook trout in central Idaho and used hierarchical regression analysis to consider whether brook trout have displaced bull trout along gradients of temperature and elevation. Brook trout generally were observed in higher numbers downstream of bull trout. Brook trout presence, number, and both temperature and elevation were important variables explaining the observed distributions and number of bull trout among streams. Our analyses support the hypothesis that brook trout have displaced bull trout, but results were highly variable and stream dependent. Although brook trout appeared to have displaced bull trout to higher elevations or colder temperatures, there was no clear influence on overall number of bull trout. Brook trout probably do influence bull trout populations and facilitate if not cause local extinctions, but threats probably vary strongly with environmental conditions. Bull trout in smaller streams could be more vulnerable than those in larger streams.

The Number of Genes for Lactate Dehydrogenase in Salmonid Fishes

1976 ◽  
Vol 33 (4) ◽  
pp. 760-767 ◽  
Author(s):  
G. S. Bailey ◽  
H. Tsuyuki ◽  
A. C. Wilson
Keyword(s):  
Lactate Dehydrogenase ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Salmo Gairdneri ◽  
Salmonid Fishes ◽  
Structural Genes ◽  
Number Of Genes ◽  
Nad Oxidoreductase ◽  
Microcomplement Fixation ◽  
Lactate Dehydrogenases

Rainbow trout (Salmo gairdneri) that show polymorphism at the ldhHα locus for liver lactate dehydrogenase (LDH) (L-lactate: NAD oxidoreductase, EC 1.1.1.27) have been examined electrophoretically and immunologically. These results show that the ldhHα locus is active in two possible allelic forms, ldhHαA and ldhHαB, in many tissues such as heart, liver, kidney, eye, red blood cell, brain, and pyloric caeca. Quantitative microcomplement fixation tests support the contention that HαA and HαB subunits are allelic variants. These results, combined with electrophoretic studies on brook trout (Salvelinus fontinalis) polymorphic at the ldhHβ locus, lead us to conclude that all isozymes for LDH in salmonid fishes can be accounted for by the activity of four, and possibly five structural loci: ldhHα, ldhHβ, ldhC, ldhMα, and possibly ldhMβ. These results are in contrast to previous suggestions that the multiple lactate dehydrogenases of trout are encoded by 8 or 10 structural genes per haploid genome.

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

Biochemical and Serological Characteristics of Ontario Isolates of Yersinia ruckeri

1982 ◽  
Vol 39 (6) ◽  
pp. 870-876 ◽  
Author(s):  
R. M. W. Stevenson ◽  
J. G. Daly
Keyword(s):  
Brook Trout ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Geographic Range ◽  
Salmo Gairdneri ◽  
Bacterial Disease ◽  
Yersinia Ruckeri ◽  
Fish Health ◽  
Brown Trout Salmo Trutta ◽  
Coregonus Artedii

During testing hatchery and wild fish from Ontario sources, we isolated bacteria that had sufficient characteristics in common with Yersinia ruckeri to suggest they were strains of this organism. Three isolates from brook trout (Salvelinus fontinalis), rainbow trout (Salmo gairdneri), and cisco (Coregonus artedii) biochemically resembled the sorbitol-fermenting Serovar II strain of Y. ruckeri, but gave cross reactions with antiserum to the Hagerman strain, Serovar I. A fourth isolate from brown trout (Salmo trutta) appeared to be different from the three previously described serovars. A fifth isolate previously obtained from muskrat (Ondatra zibethica) intestine biochemically and serologically corresponded to the Hagerman serovar. We suggest that the geographic range of Y. ruckeri and variations in its biochemical and serological properties are greater than previously believed. These findings are of significance in diagnosis and regulation of enteric redmouth disease of salmonids.Key words: Yersinia ruckeri, enteric redmouth, ERM, bacterial disease, fish health protection

Abundance and Potential Pathology of Parasites Infecting Salmonids in Canadian Maritime Hatcheries

1974 ◽  
Vol 31 (6) ◽  
pp. 1031-1036 ◽  
Author(s):  
G. M. Hare ◽  
C. Frantsi
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Brook Trout ◽  
Parasite Species ◽  
Salvelinus Fontinalis ◽  
Infection Intensity ◽  
Salmo Gairdneri ◽  
Host Age ◽  
Intensity Of Infection ◽  
First Time

Seventeen parasite species (3 protozoans, 11 helminths, 2 arthropods, and 1 mollusc) were collected from 317 Atlantic salmon (Salmo salar), 207 brook trout (Salvelinus fontinalis), and 34 rainbow trout (Salmo gairdneri) in the 13 Canadian Maritime hatcheries during 1972. Four parasites, Camallanus oxycephalus, Pomphorhynchus bulbocolli, Hydrachna sp., and a glochidium, were recorded from Atlantic salmon for the first time. Incidence and intensity of infection were high for Trichophyra piscium, Diplostomulum spathaceum, and glochidia infecting salmon and for Acanthocephalus lateralis and Salmincola edwardsii infecting brook trout. Infection intensity of Apophallus imperator, D. spathaceum, S. edwardsii, and glochidia increased with host age. Apophallus imperator and S. edwardsii were host specific to brook trout and the glochidium was host specific to salmon. Sterliadochona tenuissima and A. lateralis were more abundant in brook trout than in salmon. Pathology was associated with infections of Hexamita salmonis, D. spathaceum, A. lateralis, and S. edwardsii.

Infectious Pancreatic Necrosis Virus Occurrence at a Hatchery in Alberta

1974 ◽  
Vol 31 (4) ◽  
pp. 397-402 ◽  
Author(s):  
T. Yamamoto
Keyword(s):  
Brook Trout ◽  
Pancreatic Necrosis ◽  
Salvelinus Fontinalis ◽  
Kidney Tissue ◽  
Infectious Pancreatic Necrosis Virus ◽  
Salmo Gairdneri ◽  
Necrosis Virus ◽  
High Incidence ◽  
Infectious Pancreatic Necrosis ◽  
Pancreatic Necrosis Virus

The presence of infectious pancreatic necrosis (IPN) virus in brook (Salvelinus fontinalis) and rainbow (Salmo gairdneri) trout was identified and further investigated. A high incidence of virus was found by virological examination of kidney tissue from yearling and older trout. By comparison, brook trout had a much higher incidence of virus than rainbow trout.The virus was isolated most frequently from the kidneys of both species of trout. These findings indicate that the examinations of peritoneal washes and feces is not adequate for the detection of IPN carrier fish.

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