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.

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.

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.

Resistance of erythrocytes from Brown trout (Salmo trutta m. trutta L.) affected by ulcerative dermal necrosis syndrome

2011 ◽  
Vol 14 (3) ◽  
pp. 443-448 ◽  
Author(s):  
N. Kurhalyuk ◽  
H. Tkachenko ◽  
K. Pałczyńska
Keyword(s):  
Oxidative Stress ◽  
Lipid Peroxidation ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Thiobarbituric Acid ◽  
Control Group ◽  
Thiobarbituric Acid Reactive Substance ◽  
Tbars Level ◽  
Reactive Substance ◽  
Brown Trout Salmo Trutta

Resistance of erythrocytes from Brown trout (Salmo trutta m. trutta L.) affected by ulcerative dermal necrosis syndrome In the present work we evaluated the effect of ulcerative dermal necrosis (UDN) syndrome on resistance of erythrocytes to haemolytic agents and lipid peroxidation level in the blood from brown trout (Salmo trutta m. trutta L.). Results showed that lipid peroxidation increased in erythrocytes, as evidenced by high thiobarbituric acid reactive substance (TBARS) levels. Compared to control group, the resistance of erythrocytes to haemolytic agents was significantly lower in UDN-positive fish. Besides, UDN increased the percent of hemolysated erythrocytes subjected to the hydrochloric acid, urea and hydrogen peroxide. Results showed that UDN led to an oxidative stress in erythrocytes able to induce enhanced lipid peroxidation level, as suggested by TBARS level and decrease of erythrocytes resistance to haemolytic agents.

Evaluation of brown trout (Salmo trutta fario) fillets’ shelf life: Fed with a humic supplemented diet

2021 ◽  
Vol 29 ◽  
pp. 100675
Author(s):  
Muhammed Atamanalp ◽  
Arzu Ucar ◽  
Esat Mahmut Kocaman ◽  
Gonca Alak
Keyword(s):  
Shelf Life ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Brown Trout Salmo Trutta ◽  
Salmo Trutta Fario
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