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

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.

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%.

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.

Mouth Size and Food Size in Young Rainbow Trout, Salmo gairdneri

Copeia ◽  
1958 ◽  
Vol 1958 (3) ◽  
pp. 233 ◽  
Author(s):  
G. F. Hartman
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Mouth Size ◽  
Food Size

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)

Aggressive behavior in rainbow trout (Salmo gairdneri Richardson) of two ages

1975 ◽  
Vol 13 (4) ◽  
pp. 425-431 ◽  
Author(s):  
David Chiszar ◽  
Robert W. Drake ◽  
John T. Windell
Keyword(s):  
Rainbow Trout ◽  
Aggressive Behavior ◽  
Salmo Gairdneri

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.

Propagated Fish in Resource Management

2004 ◽  
Keyword(s):  
Rainbow Trout ◽  
Low Frequency ◽  
Cutthroat Trout ◽  
Natural Hybridization ◽  
Westslope Cutthroat Trout ◽  
Sympatric Populations ◽  
Oncorhynchus Clarkii ◽  
Mitochondrial Haplotypes ◽  
Directional Preference ◽  
Time Of Year

<em>Abstract.</em>—Westslope cutthroat trout <em>Oncorhynchus clarkii lewisi </em>are currently under a second review for listing as a threatened species under the Endangered Species Act. Both natural and anthropogenically induced hybridization has been previously documented between this subspecies and rainbow trout <em>O. mykiss </em>and between steelhead (anadromous rainbow trout) and coastal cutthroat trout <em>O. clarkii clarkii</em>. However, levels of reported introgression have varied greatly. To assess natural hybridization and the extent to which it may affect the frequency and persistence of <em>O. mykiss </em>alleles among sympatric populations of westslope trout, we used three nuclear loci to detect hybrids, and mitochondrial DNA to assess the direction of hybridization and introgression in Big Creek, Idaho and its tributaries. Natural hybridization between westslope cutthroat and sympatric rainbow trout/steelhead appears to occur at a relatively low frequency with numerous parental types still present in varying numbers within the drainage. Subsequent genetic analyses revealed no hybridization in samples from 2001 and percentages of hybrid genotypes within sample locations ranging from 1.6% to 13.3% in 2002. Differences between years may be attributable to sampling, time of year, and seasonal movements of westslope cutthroat trout and their hybrids. Furthermore, hybrids were more frequently observed (<em>p </em>< 0.01) with mitochondrial haplotypes of westslope cutthroat trout indicating a directional preference of westslope cutthroat females spawning with <em>O. mykiss </em>males.

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.

Segregation Between Adult Cutthroat Trout (Salmo clarki) and Dolly Varden (Salvelinus malma) in Small Coastal British Columbia Lakes

1971 ◽  
Vol 28 (9) ◽  
pp. 1259-1268 ◽  
Author(s):  
H. Andrusak ◽  
T. G. Northcote
Keyword(s):  
Food Habits ◽  
Cutthroat Trout ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Sympatric Populations ◽  
Dolly Varden Salvelinus Malma ◽  
Wide Range ◽  
Competition For Food ◽  
Salmo Clarki ◽  
Coastal British Columbia

Comparison of spatial distributions and food of allopatric populations of cutthroat trout (Salmo clarki) and Dolly Varden (Salvelinus malma) in two lakes and of sympatric populations in a third lake suggested interactive segregation. Allopatric cutthroat changed their depth distribution throughout the spring and summer but no diel migration was noted. Changes in food habits closely corresponded to seasonal changes in vertical distribution. A wide range of food organisms was eaten from surface, midwater, and benthic sources. Allopatric Dolly Varden underwent diel changes in spatial distribution, with many being caught in onshore waters near the surface at night. They were absent from such areas in the day, apparently occupying offshore waters at greater depths. Their diet throughout summer consisted largely of surface insects and zooplankton, with lesser amounts of bottom fauna.Sympatric cutthroat trout and Dolly Varden were spatially segregated throughout the summer. Cutthroat trout occurred and fed mostly near the surface in littoral areas. In contrast, Dolly Varden were offshore and benthic in distribution and fed primarily on bottom organisms. By comparing distribution and food habits in allopatric and sympatric populations, it was suggested that competition for food may contribute to their segregation in sympatry. Although segregation of these species when cohabiting may involve interactive processes, the possibility of selective differences being of importance cannot be dismissed.

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