Response of Wild Rainbow (Salmo gairdneri) and Cutthroat Trout (S. clarki) to Stocked Rainbow Trout in Fertile and infertile Streams

1988 ◽  
Vol 45 (12) ◽  
pp. 2087-2105 ◽  
Author(s):  
C E. Petrosky ◽  
T. C. Bjornn
Keyword(s):  
Rainbow Trout ◽  
Mortality Rate ◽  
Survival Rates ◽  
Cutthroat Trout ◽  
The Other ◽  
Salmo Gairdneri ◽  
Summer Mortality ◽  
Wild Trout ◽  
Stocking Rates

Wild rainbow trout (Salmo gairdneri) and cutthroat trout (S. clarki) were unaffected by stocking of catchable-size rainbow trout in two Idaho streams, except at the highest stocking rates, and even then the effects were limited. In the infertile stream, stocking 50 or 150 trout per section (doubling or tripling the density) did not reduce the abundance of wild cutthroat trout. Wild trout abundance declined at a faster rate in an unreplicated section stocked with 500 trout than in unstocked sections. In the fertile stream, stocking 50 or 100 hatchery trout in sections containing 26–120 similar-sized wild trout did not increase the dispersion or reduce the abundance, growth, or survival rates of wild rainbow trout. When we stocked 400 trout (100 on four dates) in sections containing 32–53 tagged wild trout of similar size, the summer mortality rate of wild trout was higher in stocked than in unstocked sections; the other parameters were not significantly different.

Introgressive Hybridization in Populations of Paiute Cutthroat Trout (Salmo clarki seleniris)

1981 ◽  
Vol 38 (8) ◽  
pp. 939-951 ◽  
Author(s):  
Craig A. Busack ◽  
G. A. E. Gall
Keyword(s):  
Population Structure ◽  
Rainbow Trout ◽  
Introgressive Hybridization ◽  
Cutthroat Trout ◽  
The Other ◽  
Salmo Gairdneri ◽  
Electrophoretic Data ◽  
The Difference ◽  
Salmo Clarki ◽  
Two Populations

Two populations of Paiute cutthroat trout (Salmo clarki seleniris) were compared meristically and electrophoretically with Lahontan cutthroat (S. c. henshawi) and rainbow trout (S. gairdneri) to elucidate population structure and verify the occurrence of introgressive hybridization. In Silver King Creek, both meristic and electrophoretic evidence indicated two populations were present, one appearing to be pure Paiute cutthroat, the other Paiute cutthroat introgressed with rainbow trout. Lahontan cutthroat introgression was a possibility in Silver King Creek but could not be evaluated because of the strong meristic and electrophoretic similarity of Paiute and Lahontan cutthroat. The other Paiute population, Cottonwood Creek, meristically appeared to be pure Paiute cutthroat but electrophoretic data indicated it was introgressed with rainbow trout. The existence of the two Silver King Creek populations indicated introgression was incomplete in that stream; introgression appeared to be complete in Cottonwood Creek. The meristic similarity of Cottonwood Creek trout to pure Paiute cutthroat was probably a result of strong selection by management agencies for a Paiute cutthroat phenotype. Electrophoresis was more discriminating than meristic analysis in this study in detecting introgression. Electrophoresis also allowed more detailed analysis of population structure than meristics because of the difference in complexity of the genetic systems analyzed by the two techniques. However, the application of both techniques contributed greatly to our understanding of introgression in the Paiute cutthroat and demonstrated the complementarity of the two approaches.Key words: Salmo clarki, Salmo gairdneri, Paiute cutthroat, Lahontan cutthroat, meristics, electrophoresis, introgression, hybridization, gametic disequilibrium, principal components

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.

Biological and Toxicologtcal Effects of Environmental Contaminants in Fish and Their Eggs

1983 ◽  
Vol 40 (3) ◽  
pp. 306-312 ◽  
Author(s):  
A. J. Niimi
Keyword(s):  
Rainbow Trout ◽  
Organic Contaminants ◽  
Yellow Perch ◽  
Survival Rates ◽  
Lake Ontario ◽  
Smallmouth Bass ◽  
Salmo Gairdneri ◽  
White Bass ◽  
Morone Chrysops ◽  
Contaminant Transfer

Rainbow trout (Salmo gairdneri), white sucker (Catostomus commersoni), white bass (Morone chrysops), smallmouth bass (Micropterus dolomieui), and yellow perch (Perca flavescens) were collected from Lakes Ontario and Erie to examine the relationship between contaminant levels in females and their eggs. Factors such as the percent lipid in the fish and percent of total lipid deposited in the eggs significantly influenced (P < 0.01) contaminant transfer. The percentages of the 9–11 organic contaminants transferred generally showed less variation within a species than the percentages for a substance transferred among the five species examined. This relationship was consistent even though there was over a 10-fold range in contaminant concentrations within a given species. Mercury did not demonstrate this response because the percentage in eggs was low for all species. The levels of PCB monitored in eggs of rainbow trout collected from Lake Ontario suggest that egg and fry survival rates could be affected based on the toxicological evidence from other studies. An examination of the possible effects of spawning on the kinetics of contaminants among these species suggests that relative body concentrations of organic contaminants may be decreased by 5% or be increased by 10%, and mercury levels may be increased by 6–22% following the deposition of eggs. The amount of change varies with species and is influenced by the percent egg weight of body weight, and the rate of contaminant transfer from females to eggs.Key words: toxicology, contaminants, reproduction, Lake Ontario, Lake Erie

Intra- and inter-specific mitochondrial DNA sequence divergence in Salmo: rainbow, steelhead, and cutthroat trouts

1985 ◽  
Vol 63 (9) ◽  
pp. 2088-2094 ◽  
Author(s):  
Gary M. Wilson ◽  
W. Kelley Thomas ◽  
Andrew T. Beckenbach
Keyword(s):  
Mitochondrial Dna ◽  
Rainbow Trout ◽  
Life Histories ◽  
Sequence Divergence ◽  
Cutthroat Trout ◽  
Restriction Enzymes ◽  
Restriction Endonuclease Analysis ◽  
Salmo Gairdneri ◽  
Intraspecific Divergence ◽  
Clonal Lines

Two forms of Salmo gairdneh with different life histories (steelhead and rainbow trout) were compared using restriction endonuclease analysis of mitochondrial DNA. A total of 19 individuals from four populations were studied for each of the two forms, using 14 restriction enzymes. In addition, five cutthroat trout samples were included as an interspecific comparison. These enzymes revealed a total of 81 cut sites, representing a sample of more than 400 nucleotides per fish. Of these sites, 25 were phylogenetically informative, dividing the 43 fish into 10 clonal lines, 8 Salmo gairdneri and 2 Salmo clarki. Results indicated detectable divergence between all geographic populations of steelhead and rainbow trout except Pennask rainbow trout, Coquihalla steelhead, and Wampus Creek rainbow trout. Other steelhead populations analysed showed a closer phylogenetic relationship to each other than to rainbow trout populations analysed. Intraspecific divergence was in most cases 1% or less, with a 1.5% maximum. Interspecific divergence between S. gairdneri and S. clarki was between 2% and 3.5%.

Rainbow Trout (Salmo gairdneri) and Cutthroat Trout (S. clarki) Interactions in Coastal British Columbia Lakes

1981 ◽  
Vol 38 (10) ◽  
pp. 1228-1246 ◽  
Author(s):  
Nils-Arvid Nilsson ◽  
Thomas G. Northcote
Keyword(s):  
Rainbow Trout ◽  
Aggressive Behavior ◽  
Prey Capture ◽  
Cutthroat Trout ◽  
Maximum Size ◽  
Salmo Gairdneri ◽  
Sympatric Populations ◽  
Food Size ◽  
Coastal British Columbia ◽  
Trout Feeding

Food, size, and growth of 17 allopatric and 10 sympatric lake populations of rainbow trout (Salmo gairdneri) and cutthroat trout (S. clarki) were compared as well as their aggressive behavior during feeding in experimental tanks. In allopatry, rainbow trout fed extensively on benthic, midwater, and surface prey. Allopatric cutthroat utilized mostly midwater prey but in contrast with rainbow trout also fish (Cottus, Gasterosteus) when available. In sympatry, rainbow trout exploited mainly limnetic surface and midwater prey whereas cutthroat trout utilized more littoral prey and were much more piscivorous in feeding. Allopatric rainbow attained a greater average and maximum size (length, weight) than allopatric cutthroat whereas in sympatric populations cutthroat were clearly larger than rainbow. Growth (size at specific ages) usually was higher for rainbow compared with cutthroat trout in allopatric populations but just the reverse in sympatric populations. When held as matched pairs in aquaria, rainbow consistently were more aggressive than cutthroat trout and displayed different patterns of threat as well as means of prey capture. Differences in feeding and growth in sympatry may result from interactive segregation, the more pronounced aggressiveness of rainbow promoting higher growth in cutthroat trout.Key words: rainbow trout, cutthroat trout, feeding, growth, habitat, aggressive behavior, feeding behavior, interactive segregation

Changes in the visual pigments of trout

1973 ◽  
Vol 51 (9) ◽  
pp. 901-914 ◽  
Author(s):  
Donald M. Allen ◽  
William N. McFarland ◽  
Frederick W. Munz ◽  
Hugh A. Poston
Keyword(s):  
Rainbow Trout ◽  
Brown Trout ◽  
Visual Pigment ◽  
Brook Trout ◽  
Forest Canopy ◽  
Environmental Control ◽  
Cutthroat Trout ◽  
Visual Pigments ◽  
Salmo Gairdneri ◽  
Canopy Access

The proportions of two visual pigments (rhodopsin and porphyropsin) were examined in four species of trout under experimental and natural conditions. Brook trout (Salvelinus fontinalis), rainbow trout (Salmo gairdneri), and brown trout (Salmo trutta) have different relative proportions of visual pigments in their retinae. The visual pigment balance in wild cutthroat trout (Salmo clarki) is related to forest canopy (access to light) and season. The brown trout have a more red-sensitive and less labile pair of visual pigments than brook or rainbow trout, which respond to photic conditions by increasing the proportion of porphyropsin (in light) and increasing rhodopsin (in darkness). The brown trout have a high percentage of porphyropsin, regardless of experimental conditions. This result does not reflect an inability to form rhodopsin but rather may relate to a consistently high proportion of 3-dehydroretinol in the pigment epithelium. The possible advantages and mechanisms of environmental control of trout visual pigment absorbance, as currently understood, are discussed.

pHi, contractility and Ca-balance under hypercapnic acidosis in the myocardium of different vertebrate species

1982 ◽  
Vol 96 (1) ◽  
pp. 405-412
Author(s):  
H. Gesser ◽  
E. Jorgensen
Keyword(s):  
Rainbow Trout ◽  
Negative Inotropic Effect ◽  
The Other ◽  
Inotropic Effect ◽  
Salmo Gairdneri ◽  
Hypercapnic Acidosis ◽  
Hydrogen Ions ◽  
Vertebrate Species ◽  
High Co2 ◽  
Intracellular Ca

The influence of hypercapnic acidosis upon the heart was examined in four vertebrate species. The CO2 in the tissue bath was increased from 2.7 to 15% at 12 degrees C for flounder (Platichthys flesus) and cod (Gadus morhua) and from 3 to 13% at 22 degrees C for turtle (Pseudemys scripta) and rainbow trout (Salmo gairdneri). During hypercapnia, as previously described, there was a decline and recovery of contractility in heart strips of flounder and turtle, and a sustained decrease in cod and rainbow trout. At high CO2 the increase in contractile force following increases in the extracellular Ca-concentration were smaller for the cod myocardium than for the other myocardia. The intracellular pH (pHi), measured with the DMO method, in heart strips of turtle and trout was significantly lower at high than at low CO2. This acidifying effect expressed as the increase in the intracellular concentration of hydrogen ions was larger in the turtle than in the trout myocardium. Intracellular Ca-activity, measured by efflux of 45Ca from preloaded heart strips, was unaffected by high CO2 in trout, but was raised in the other three species. Thus the ability to counteract the negative inotropic effect of hypercapnia is apparently not due to cellular buffering or extrusion of hydrogen ions. More probably it involves (a) a release of intracellular Ca; (b) a positive inotropic effect of an increase in intracellular Ca-activity.

Electrophoretic Distinction of Rainbow Trout (Salmo gairdneri), West-Slope Cutthroat Trout (S. clarki), and Their Hybrids

1977 ◽  
Vol 34 (8) ◽  
pp. 1236-1239 ◽  
Author(s):  
Gary L. Reinitz
Keyword(s):  
Rainbow Trout ◽  
Key Words ◽  
Biochemical Marker ◽  
Cutthroat Trout ◽  
Phosphoglucose Isomerase ◽  
Western Montana ◽  
Salmo Gairdneri ◽  
Native Populations ◽  
Salmo Clarki

Rainbow trout (Salmo gairdneri), west-slope cutthroat trout (Salmo clarki), and their F1 hybrids were electrophoretically examined for 13 different proteins. Of the 13 proteins, only phosphoglucose isomerase (PGI) proved to be a reliable biochemical marker for the distinction of genetically pure samples of the two species. Only PGI provided an accurate means of identifying F1 hybrids between the species. This information could possibly be used to facilitate the stabilization and restoration of native populations of west-slope cutthroat trout in western Montana. Key words: rainbow trout, west-slope cutthroat trout, hybridization, electrophoresis, biochemical marker, phosphoglucose isomerase (PGI)

Visual pigment changes in the rainbow trout, Salmo gairdneri

1972 ◽  
Vol 50 (8) ◽  
pp. 1117-1126 ◽  
Author(s):  
W. L. Jacquest ◽  
D. D. Beatty
Keyword(s):  
Rainbow Trout ◽  
Visual Pigment ◽  
Intramuscular Injection ◽  
Visual Pigments ◽  
The Other ◽  
Salmo Gairdneri ◽  
Thyrotropic Hormone

The retinae of rainbow trout, Salmo gairdneri, have mixtures of two visual pigments, one based on retinaldehyde (VP5031), the other on 3-dehydroretinaldehyde (VP5272). Increases in the proportion of VP5272 or maintained high percentages of VP5272 were induced in three ways: (1) feeding a diet rich in 3-dehydroretinol; (2) intraperitoneal injections of L-thyroxine; and (3) intramuscular injection of bovine thyrotropic hormone. The possible significance of these findings in relation to carotenoid conversions in fish is discussed.

scholarly journals Hybridization between Cutthroat and Rainbow Trout: Evidence from Biochemical Genetic Loci

1979 ◽  
Vol 3 ◽  
pp. 108-112
Author(s):  
Eric Loudenslager ◽  
G. Gall
Keyword(s):  
Rainbow Trout ◽  
Related Species ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Genetic Loci ◽  
Species Identity ◽  
Closely Related Species ◽  
Isolating Mechanisms ◽  
Biochemical Genetic ◽  
Salmo Clarki

Cutthroat, Salmo clarki, and rainbow, Salmo gairdneri, trout are largely allopatric, closely related species. Where naturally sympatric ecological isolating mechanisms maintain species identity. However, the inland subspecies of cutthroat trout which did not evolve in sympatry with rainbows are thought to freely hybridize with rainbow trout which have been introduced for recreational purposes. Because of the mass introductions of rainbow trout fish managers have become increasingly concerned about the purity of the dwindling stocks of native cutthroats.

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