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

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.

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.

The effects of introduction of brown trout (Salmo trutta L.) on Gammarus pulex L. drift and density in two fishless Danish streams

1993 ◽  
Vol 126 (3) ◽  
pp. 361-371
Author(s):  
Thomas Harcke Andersen ◽  
Nicolai Friberg ◽  
Hans Ole Hansen ◽  
Torben Moth Iversen ◽  
Lars Krøjgaard
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Gammarus Pulex ◽  
Brown Trout Salmo Trutta

Occurrence of two species of Crepidostomum in brown trout (Salmo trutta L.) from north-east Ireland, with special reference to Crepidostomum metoecus Braun 1900

Parasitology ◽  
1955 ◽  
Vol 45 (1-2) ◽  
pp. 186-188 ◽  
Author(s):  
M. Pauline Corbett
Keyword(s):  
Special Reference ◽  
Fresh Water ◽  
Brown Trout ◽  
New Record ◽  
Salmo Trutta ◽  
Helminth Fauna ◽  
British Isles ◽  
North East ◽  
Brown Trout Salmo Trutta ◽  
Common Parasite

During the course of preliminary studies on the helminth fauna of local freshwater fishes two species of Crepidostomum, obtained from the intestine of brown trout, were identified as C. farionis (Müller) and C. metoecus Braun. Although C.farionis is a common parasite of the fresh-water salmonoid fishes of the Northern Hemisphere, in Ireland it has been recorded only from trout (Salmo trutta). The first Irish specimens were recorded by Southern (1912) as Stephanophiala laureata (Zeder), and came from fish from a stream in Clare Island and from the Owenwee River, Westport. Later, Vickers (1951) found that trout from the River Moyola, Co. Londonderry, and River Ravarnett, Co. Down, were infected with this species. Prior to the present study, C. farionis was the only representative of the genus to have been recorded from the British Isles. C. metoecus is therefore a new record, not only from Ireland, but from the British Isles as well. Elsewhere it is known to occur in Sweden [ = C. suecicum Nybelin, 1933], Austria, and possibly also in Thuringia, where cercariae were found which Nöller (1928) assigned to C. metoecus.

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

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