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.

Testing a model of drift-feeding using three-dimensional videography of wild brown trout, Salmo trutta, in a New Zealand river

2003 ◽  
Vol 60 (12) ◽  
pp. 1462-1476 ◽  
Author(s):  
Nicholas F Hughes ◽  
John W Hayes ◽  
Karen A Shearer ◽  
Roger G Young
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Focal Point ◽  
Three Dimensional ◽  
Size Composition ◽  
Invertebrate Drift ◽  
Intake Rate ◽  
Drift Feeding ◽  
Foraging Area ◽  
Brown Trout Salmo Trutta

We tested the assumptions and predictions of a foraging model for drift-feeding fish. We used three-dimensional videography to describe the foraging behavior of brown trout, Salmo trutta, mapped water depth and velocity in their foraging area, sampled invertebrate drift to determine length class specific drift densities, and captured trout to determine the size composition of their diet. The model overestimated the fish's prey capture rate and gross energy intake rate by a factor of two. Most of this error resulted from the fact that prey detection probabilities within the fish's foraging area averaged only half the expected value. This was the result of a rapid decrease in capture probability with increasing lateral distance from the fish's focal point. Some of the model's assumptions were accurate: equations for predicting reaction distance and minimum prey size supported reliable predictions of the shape and size of the fish's foraging area and the size composition of the diet. Other assumptions were incorrect: fish detected prey within the predicted reaction volume, not on its upstream surface as expected, fish intercepted prey more slowly than the expected maximum sustainable swimming speed, and fish captured about two-thirds of their prey downstream of their focal point, rather than upstream.

Spatial and temporal effects of interspecific competition between Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in winter

2001 ◽  
Vol 58 (6) ◽  
pp. 1133-1140 ◽  
Author(s):  
A J Harwood ◽  
N B Metcalfe ◽  
J D Armstrong ◽  
S W Griffiths
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Habitat Preferences ◽  
Flowing Water ◽  
Stream Channels ◽  
Growth And Survival ◽  
Atlantic Salmon Salmo Salar ◽  
Brown Trout Salmo Trutta

Previous work has shown that juvenile stream-dwelling salmonids become predominantly nocturnal during winter by emerging from daytime refuges to feed, with several species having been shown to prefer slow-flowing water while active at night. We used seminatural stream channels, landscaped to provide a choice of water depths, and hence velocities, to test whether Atlantic salmon, Salmo salar, and brown trout, Salmo trutta, show similar habitat preferences during winter. We also tested whether there was any spatial or temporal displacement of Atlantic salmon when in sympatry with brown trout. Nighttime observations revealed that Atlantic salmon did have a preference for slow-flowing water. However, when in direct competition with trout, salmon either remained predominantly nocturnal but occupied shallower water, or became significantly less nocturnal, spending more time active during the day than when in allopatry. These results, which were especially marked in relatively larger fish, indicate that competition between the two species for food and resources is not restricted to the summer months and may affect both the short- and long-term growth and survival of overwintering wild Atlantic salmon.

Effects of woody debris and the supply of terrestrial invertebrates on the diet and growth of brown trout (Salmo trutta) in a boreal stream

2014 ◽  
Vol 59 (12) ◽  
pp. 2488-2501 ◽  
Author(s):  
Pär Gustafsson ◽  
Larry A. Greenberg ◽  
Eva Bergman
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Woody Debris ◽  
Terrestrial Invertebrates ◽  
Brown Trout Salmo Trutta

Woody debris and terrestrial invertebrates – effects on prey resources for brown trout (Salmo trutta) in a boreal stream

2014 ◽  
Vol 97 (5) ◽  
pp. 529-542 ◽  
Author(s):  
Pär Gustafsson ◽  
Larry A. Greenberg ◽  
Eva Bergman
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Woody Debris ◽  
Terrestrial Invertebrates ◽  
Brown Trout Salmo Trutta ◽  
Prey Resources

Functional Responses of Brown Trout (Salmo trutta L.) to Invertebrate Drift

1983 ◽  
Vol 2 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Neil H. Ringler ◽  
David F. Brodowski
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Invertebrate Drift ◽  
Functional Responses ◽  
Brown Trout Salmo Trutta

The effect of brown trout (Salmo Trutta L.) on stream invertebrate drift, with special reference to Gammarus pulex L.

Hydrobiologia ◽  
1994 ◽  
Vol 294 (2) ◽  
pp. 105-110 ◽  
Author(s):  
N. Friberg ◽  
T. H. Andersen ◽  
H. O. Hansen ◽  
T. M. Iversen ◽  
D. Jacobsen ◽  
...  
Keyword(s):  
Special Reference ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Gammarus Pulex ◽  
Invertebrate Drift ◽  
Brown Trout Salmo Trutta

Selective Predation by Drift-Feeding Brown Trout (Salmo trutta)

1979 ◽  
Vol 36 (4) ◽  
pp. 392-403 ◽  
Author(s):  
Neil H. Ringler
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Prey Size ◽  
Energy Content ◽  
Feeding Strategy ◽  
Invertebrate Drift ◽  
Selective Predation ◽  
Heterogeneous Distribution ◽  
Brown Trout Salmo Trutta ◽  
Dominant Characteristic

Consumption of three species of prey by brown trout (Salmo trutta) in a laboratory stream was studied during 7-d experiments. Two drift rates (5 and 10 organisms/min) and three ratios (1:1, 2:1, 5:1) of small:large alternative prey were employed. Responses to prey species stabilized after 4–6 d and 800–1200 prey captures, but no prey was completely excluded from the diet. Size-selective predation was a dominant characteristic of the response. The fish appeared to alter the area (depth) searched in response to prey density; electivity was greatest when prey densities were high. Disproportionate predation on abundant prey ("switching") was a temporary phenomenon, which may have been masked by prey size. Brown trout ultimately achieved 54–91% of a hypothetical diet in which prey are ranked in order of size (energy content). Deviations from an optimal diet may be explained in terms of a feeding strategy that deals with heterogeneous distribution of prey, as well as with the behavioral capabilities of the predator. Key words: behavior, fish, invertebrate drift, optimal foraging, predation, prey size and abundance, Salmonidae, search image, streams

Do different predators affect distance, direction, and destination of movements by a stream mayfly?

1998 ◽  
Vol 55 (8) ◽  
pp. 1954-1960 ◽  
Author(s):  
Angus R McIntosh ◽  
Colin R Townsend
Keyword(s):  
Brown Trout ◽  
Current Velocity ◽  
Salmo Trutta ◽  
Exponential Model ◽  
Movement Direction ◽  
Stream Channels ◽  
Direct Response ◽  
Brown Trout Salmo Trutta ◽  
Negative Exponential Model ◽  
Negative Exponential

We observed the directions and distances travelled by Nesameletus ornatus mayfly nymphs in stream channels (current velocity 18 cm·s-1) with either Eldon's galaxias (Galaxias eldoni), brown trout (Salmo trutta), or no fish. Short (<20 cm) upstream movements were most common, but movements up to 90 cm in both directions were recorded. Predators had no significant impact on movement direction or distance compared with controls when all movements were considered. Only movements in direct response to galaxias were significantly longer and more likely to be in a downstream direction than movements not directly associated with galaxias. In most cases the frequency of downstream drift distances fitted a negative exponential model. Our results showed that when current and turbulence were low, N. ornatus could have considerable control over their movement.

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