Diel Food Selection by Two Sizes of Rainbow Trout (Salmo gairdneri) in an Experimental Stream

1978 ◽  
Vol 35 (7) ◽  
pp. 971-975 ◽  
Author(s):  
Peter A. Bisson
Keyword(s):  
Rainbow Trout ◽  
Prey Size ◽  
Feeding Activity ◽  
Food Selection ◽  
Salmo Gairdneri ◽  
Invertebrate Drift ◽  
Small Fish ◽  
Drift Density ◽  
Experimental Stream ◽  
Selection Of

The food selected by small (~ 3 g) and large (~ 45 g) hatchery rainbow trout (Salmo gairdneri), studied over a 28-h period, showed that the fish fed selectively, but often on different prey organisms. Feeding activity was highest during daylight hours but was only loosely associated with increases in invertebrate drift density. The majority of large trout exploited adult chironomids on the surface, whereas small trout fed primarily on midwater drift. At night when drift densities were low the limited feeding that took place apparently shifted to bottom foraging. Prey size was the most important factor affecting vulnerability to predation at all hours. Both large and small fish rarely consumed invertebrates < 2 mm long. Selection of larger individuals among certain prey taxa occurred, and in two important groups (Trichoptera and Chironomidae) large trout ate significantly larger prey than did small trout. By being size selective, the trout lost the opportunity to exploit smaller organisms, particularly Collembola, which constituted the bulk of the total drift. Key words: diel habits, drift, predation, rainbow trout, size selection

Temperature Selection of Rainbow Trout (Salmo gairdneri) Fingerlings in Vertical and Horizontal Gradients

1971 ◽  
Vol 28 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
R. W. McCauley ◽  
W. L. Pond
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Temperature Preference ◽  
Temperature Selection ◽  
Horizontal Gradients ◽  
Significant Difference ◽  
Preferred Temperatures ◽  
Laboratory Investigations ◽  
Horizontal Temperature Gradients ◽  
Selection Of

Preferred temperatures of underyearling rainbow trout (Salmo gairdneri) were determined in both vertical and horizontal temperature gradients. No statistically significant difference was found between the preferred temperatures by the two different methods. This suggests that the nature of the gradient plays a lesser role than generally believed in laboratory investigations of temperature preference.

As the prey thickens: rainbow trout select prey based upon width not length

2021 ◽  
pp. 1-11
Author(s):  
Michael J. Dodrill ◽  
Charles B. Yackulic ◽  
Theodore A. Kennedy ◽  
Michael D. Yard ◽  
Josh Korman
Keyword(s):  
Rainbow Trout ◽  
Prey Size ◽  
Choice Model ◽  
Prey Selection ◽  
Invertebrate Drift ◽  
Fish Length ◽  
Larval Stages ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Selective Foraging ◽  
Length Width

Drift-feeding fish are typically considered size-selective predators. Yet, few studies have explicitly tested which aspect of prey “size” best explains size selection by drift-foraging fish. Here, we develop a Bayesian discrete choice model to evaluate how attributes of both prey and predator simultaneously influence size-selective foraging. We apply the model to a large dataset of paired invertebrate drift (n = 784) and rainbow trout (Oncorhynchus mykiss) diets (n = 1028). We characterized prey “size” using six metrics (length, width, area, hemispherical area, volume, mass) and used pseudo-R2 to determine which metric best explained observed prey selection across seven taxa. We found that rainbow trout are positively size-selective, they are selecting prey based upon differences in prey width, and size-selectivity increases with fish length. Rainbow trout demonstrated strong selection for the adult and pupae stages of aquatic insects relative to their larval stages. Our study provides strong empirical evidence for size-selective foraging in rainbow trout and demonstrates prey selection is based primarily upon width, not length or area as has been widely reported.

Selection by Young Rainbow Trout (Salmo gairdneri) in Simulated Stream Environments For Live and Dead Prey of Different Sizes

1983 ◽  
Vol 40 (10) ◽  
pp. 1745-1749 ◽  
Author(s):  
J. R. Irvine ◽  
T. G. Northcote
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Live Prey ◽  
Feeding Experience ◽  
Wide Range ◽  
Experimental Stream ◽  
Dead Prey

Underyearling rainbow trout (Salmo gairdneri) in experimental stream tanks presented with live and dead prey preferred live prey. Trout fry generally were size selective predators and previous feeding experience did not affect the size of prey consumed. When a wide range of prey sizes was offered, larger trout fry fed upon bigger prey than did smaller fry. Cyclops were underrepresented in trout fry stomachs relative to Daphnia of similar size.

Effects of woody debris on the growth and behaviour of brown trout in experimental stream channels

1998 ◽  
Vol 76 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Karl Sundbaum ◽  
Ingemar Näslund
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Woody Debris ◽  
Feeding Activity ◽  
Control Channel ◽  
Invertebrate Drift ◽  
Stream Channels ◽  
Gravel Bed ◽  
Brown Trout Salmo Trutta ◽  
Experimental Stream

We examined the effects of woody debris on the growth and behaviour of brown trout (Salmo trutta) in experimental stream channels. Two types of habitat were used in the study: a complex habitat created by placing woody debris on a gravel bed and a uniform habitat consisting of a gravel bed only. The experiment was run both outdoors with wild fish that fed on natural invertebrate drift and indoors with hatchery fish that were fed artificial food. In both treatments most of the fish lost mass. In all trials, however, the fish in the woody debris channel lost less mass than the fish in the control channel. Study of the fishes' behaviour revealed less swimming activity, less aggression, and less feeding activity in the woody debris channel than in the control channel. The results of this study indicate that the presence of woody debris decreases intraspecific competition through visual isolation, allowing fish to reduce aggressive interactions and energy expenditure.

Effects of Illumination on Behavior of Wild Brown (Salmo trutta) and Rainbow Trout (Salmo gairdneri) Exposed to Black and White Backgrounds

1973 ◽  
Vol 30 (12) ◽  
pp. 1875-1880 ◽  
Author(s):  
John A. Ritter ◽  
Hugh R. MacCrimmon
Keyword(s):  
Rainbow Trout ◽  
Salmo Trutta ◽  
Salmo Gairdneri ◽  
White Background ◽  
Activity Levels ◽  
Sudden Increase ◽  
Experimental Tank ◽  
Protective Response ◽  
Black And White ◽  
Selection Of

Wild brown (Salmo trutta) and rainbow trout (Salmo gairdneri) placed in a circular tank illuminated at 10−2 lx immediately selected black rather than white background. Preference for black fluctuated with activity during the first 2 hr while both selection of black and activity gradually decreased with habituation over the following 84 hr. A sudden increase in illumination to 200 lx reestablished the strong selection of black which decreased rapidly with rising activity. Selection of black was inversely correlated with activity of the fish and was greater under moving than nonmoving water conditions. Differences in activity levels between rainbow and brown trout caused minor differences in response to background.Temporal preference for black background is interpreted as a protective response to the fright stimuli of initial handling, unfamiliarity with the experimental tank, and sudden increase in illumination. Duration of the response after the sudden increase in illumination was less in brown than rainbow trout. Because of its influence on activity and selection of light or dark backgrounds, light is an important ecological factor for trout.

Effect of Growth Rate and Size of Fish on Rate of Intoxication by Waterfoorne Lead

1982 ◽  
Vol 39 (9) ◽  
pp. 1243-1251 ◽  
Author(s):  
Peter V. Hodson ◽  
D. George Dixon ◽  
Douglas J. Spry ◽  
D. M. Whittle ◽  
John B. Sprague
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Lake Trout ◽  
Whole Body ◽  
Salmo Gairdneri ◽  
Small Fish ◽  
Rainbow Smelt ◽  
Fish Size ◽  
Threshold Size ◽  
Juvenile Rainbow Trout

Three experiments were undertaken to test the null hypotheses that increasing fish size and growth rate do not increase the rate of intoxication of fish by lead. The first experiment demonstrated that there were no significant correlations between weight of fish and either whole-body or blood lead concentrations in feral lake trout (Salvelinus namaycush). The whole-body lead concentration of rainbow smelt (Osmerus mordax) was, however, negatively correlated to wet weight.During the second experiment, an 8-d laboratory exposure of rainbow trout (Salmo gairdneri) to 100 μg/L of total waterborne lead caused a greater uptake of lead by opercular bone in small fish than in larger fish. No relationship was apparent between fish weight and uptake of lead by blood.Chronic exposure of juvenile rainbow trout to lead results in the development of black tails, a symptom of neurotoxicity. The final experiment related the incidence and prevalence of black tails to size and growth rate (ration level) of juvenile rainbow trout chronically exposed to 543 μg/L of total waterborne lead starting with the sac-fry stage. At weights below a common threshold size of 1.5–2.5 g, no black tails occurred; above this threshold the incidence of black tails was a function of growth rate, i.e. the rate at which fish reached the threshold size. The prevalence of black tails was always less in slowly growing fish.These experiments demonstrated that the rate of intoxication by lead, as indicated by uptake rates into tissues and the incidence and prevalence of a symptom of neurotoxicity, did not increase with fish size, but rather with growth rate.Key words: fish, toxicity, lead, fish size, growth rate, neurotoxicity, uptake

Night Feeding of Brown and Rainbow Trout in an Experimental Stream Channel

1969 ◽  
Vol 26 (12) ◽  
pp. 3275-3278 ◽  
Author(s):  
Thomas M. Jenkins Jr.
Keyword(s):  
Rainbow Trout ◽  
Salmo Trutta ◽  
Salmo Gairdneri ◽  
Mountain Stream ◽  
Stream Channel ◽  
Fish Feeding ◽  
Feeding Tubes ◽  
Night Feeding ◽  
Terrestrial Insects ◽  
Experimental Stream

This study sought to determine if stream-living brown and rainbow trout (Salmo trutta and Salmo gairdneri) will feed on drifting terrestrial insects at night. Groups of fish were confined in segments of a rocky-substrate mountain stream, and marked ants were introduced to the current from observation towers equipped with feeding tubes. After the last introductions of an experiment, the fish were removed and their stomachs were examined for marked ants.Although fish of both species fed at night, they appeared to take a smaller percentage of the ants provided than did day-feeding groups studied for comparison. Fish feeding under bright moonlight and starlight captured introduced ants at about the same rates. The results suggest that trout in the type of stream studied feed or are in feeding readiness at nearly all hours of the day or night, at least in the summer months.

Risk of Epibenthic Prey to Predation by Rainbow Trout (Salmo gairdneri)

1973 ◽  
Vol 30 (6) ◽  
pp. 787-797 ◽  
Author(s):  
D. M. Ware
Keyword(s):  
Rainbow Trout ◽  
Prey Size ◽  
Food Resource ◽  
Independent Set ◽  
Equation System ◽  
Benthic Invertebrate ◽  
Salmo Gairdneri ◽  
Food Chains ◽  
Prey System ◽  
Benthic Food

A model is developed to describe the risk of aquatic prey to visual predators in general, and is evaluated with particular reference to rainbow trout (Salmo gairdneri). The equation system uses several principles of visual mechanics to determine predation rates and therefore requires statistics on the physical properties of the food resource, besides the visual acuity and other searching constraints of the predator.Application of the model to an independent set of field data accounted for 47% of the seasonal variation in the occurrence of four benthic invertebrate prey in the diet of trout from Marion Lake, B.C. Considerably better agreement — 70% of the variation — was obtained using a three prey system. Sequential comparisons between the predicted and observed pattern of predation suggest that prey activity, prey exposure, prey density, and prey size are four of the major determinants of prey risk in benthic food chains.

Temperature Selection and Estimated Thermal Acclimation by Rainbow Trout (Salmo gairdneri) in a Thermal Plume

1979 ◽  
Vol 36 (4) ◽  
pp. 366-376 ◽  
Author(s):  
S. A. Spigarelli ◽  
M. M. Thommes
Keyword(s):  
Rainbow Trout ◽  
Body Temperature ◽  
Lake Michigan ◽  
Salmo Gairdneri ◽  
Small Fish ◽  
Thermal Plume ◽  
Body Temperatures ◽  
Preferred Temperature ◽  
Temperature Selection ◽  
Discharge Temperature

Body temperatures of rainbow trout (Salmo gairdneri) caught from a thermal discharge into Lake Michigan were used to determine selected temperatures and to estimate acclimation temperatures of this species under field conditions. Approximately 65–75% of the variability in body temperatures was related to water temperature (direct) and fish weight (inverse). Body temperatures increased with increases in discharge temperature, but the difference between body and ambient water temperatures decreased at high water temperatures. The modal body temperature of small fish was 19 °C, the final preferred temperature predicted for rainbow trout by some lab studies. The modal body temperature of large fish was 15 °C. Estimates of acclimation temperatures indicate that the majority of rainbow trout caught in this discharge area were acclimated to plume temperatures. Estimated acclimation temperatures exceeded ambient acclimation by as much as 10 °C for individual fish while group means ranged between 2 and 6 °C over ambient acclimation. Key words: temperature selection, acclimation, thermal plume, rainbow trout, Lake Michigan, body temperature, size effect

Sign in / Sign up

Export Citation Format

Share Document