scholarly journals State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

2015 ◽  
Author(s):  
Joacim Näslund ◽  
Jörgen I Johnsson
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Population Based ◽  
Swimming Activity ◽  
The Other ◽  
Behavioral Strategies ◽  
Food Ration ◽  
State Dependent ◽  
Behavioral Trials ◽  
Bodily State

Animals generally adjust their behavior in response to bodily state (e.g. size and energy reserves) to optimize energy intake in relation to mortality risk, weighing predation probability against starvation. Here we investigated whether brown trout adjust their behavior in relation to feeding history (energetic status) and body size during a major early-life selection bottleneck, when fast growth also appear to be important. We manipulated growth using different food ration schemes over two consecutive time periods (P1 = 12 days, P2 = 23 days), excluding social effects through individual isolation. During these experimental periods the fish were fed either high or low food rations in a crossed design. In behavioral trials following the treatment, where acute hunger levels were standardized among all treatments, fish that were initially fed high rations (P1) and thereafter low rations (P2) had on average 15-21% higher swimming activity than the other groups, but large within-treatment variation rendered only weak statistical support for the effect. Furthermore, fish on low ration during P2 tended to be more aggressive than fish on high ration. Size was related to behavioral expression, with larger fish being more active and aggressive. Swimming activity and active aggression were positively correlated, forming a behavioral syndrome in the studied population. Based on these behavioral traits we could also distinguish two behavioral clusters, one consisting of more active and aggressive individuals, and the other consisting of less active and aggressive individuals. This indicates that two behavioral strategies may exist in young brown trout.

scholarly journals State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

2015 ◽  
Author(s):  
Joacim Näslund ◽  
Jörgen I Johnsson
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Population Based ◽  
Swimming Activity ◽  
The Other ◽  
Behavioral Strategies ◽  
Food Ration ◽  
State Dependent ◽  
Behavioral Trials ◽  
Bodily State

Animals generally adjust their behavior in response to bodily state (e.g. size and energy reserves) to optimize energy intake in relation to mortality risk, weighing predation probability against starvation. Here we investigated whether brown trout adjust their behavior in relation to feeding history (energetic status) and body size during a major early-life selection bottleneck, when fast growth also appear to be important. We manipulated growth using different food ration schemes over two consecutive time periods (P1 = 12 days, P2 = 23 days), excluding social effects through individual isolation. During these experimental periods the fish were fed either high or low food rations in a crossed design. In behavioral trials following the treatment, where acute hunger levels were standardized among all treatments, fish that were initially fed high rations (P1) and thereafter low rations (P2) had on average 15-21% higher swimming activity than the other groups, but large within-treatment variation rendered only weak statistical support for the effect. Furthermore, fish on low ration during P2 tended to be more aggressive than fish on high ration. Size was related to behavioral expression, with larger fish being more active and aggressive. Swimming activity and active aggression were positively correlated, forming a behavioral syndrome in the studied population. Based on these behavioral traits we could also distinguish two behavioral clusters, one consisting of more active and aggressive individuals, and the other consisting of less active and aggressive individuals. This indicates that two behavioral strategies may exist in young brown trout.

scholarly journals Higher mortality of the less suitable brown trout host compared to the principal Atlantic salmon host when infested with freshwater pearl mussel (Margaritifera margaritifera) glochidia

2021 ◽  
Author(s):  
Janhavi Marwaha ◽  
Per Johan Jakobsen ◽  
Sten Karlsson ◽  
Bjørn Mejdell Larsen ◽  
Sebastian Wacker
Keyword(s):  
Atlantic Salmon ◽  
Brown Trout ◽  
Host Species ◽  
Salmo Trutta ◽  
The Other ◽  
Margaritifera Margaritifera ◽  
Pearl Mussel ◽  
Suitable Host ◽  
Freshwater Pearl Mussel ◽  
Host Interaction

AbstractThe freshwater pearl mussel (Margaritifera margaritifera) is a highly host-specific parasite, with an obligate parasitic stage on salmonid fish. Atlantic salmon (Salmo salar) and brown trout (Salmo trutta f. trutta and Salmo trutta f. fario) are the only hosts in their European distribution. Some M. margaritifera populations exclusively infest either Atlantic salmon or brown trout, while others infest both hosts with one salmonid species typically being the principal host and the other a less suitable host. Glochidial abundance, prevalence and growth are often used as parameters to measure host suitability, with the most suitable host species displaying the highest parameters. However, it is not known if the degree of host specialisation will negatively influence host fitness (virulence) among different host species. In this study we examined the hypothesis that glochidial infestation would result in differential virulence in two salmonid host species and that lower virulence would be observed on the most suitable host. Atlantic salmon and brown trout were infested with glochidia from two M. margaritifera populations that use Atlantic salmon as their principal host, and the difference in host mortality among infested and control (sham infested) fish was examined. Higher mortality was observed in infested brown trout (the less suitable host) groups, compared to the other test groups. Genetic assignment was used to identify offspring from individual mother mussels. We found that glochidia from individual mothers can infest both the salmonid hosts; however, some mothers displayed a bias towards either salmon or trout. We believe that the differences in host-dependent virulence and the host bias displayed by individual mothers were a result of genotype × genotype interactions between the glochidia and their hosts, indicating that there is an underlying genetic component for this parasite-host interaction.

Influence of food abundance on individual behaviour strategy and growth rate in juvenile brown trout (Salmo trutta)

2003 ◽  
Vol 81 (4) ◽  
pp. 684-692 ◽  
Author(s):  
Eva Brännäs ◽  
Sara Jonsson ◽  
Hans Lundqvist
Keyword(s):  
Brown Trout ◽  
Growth Rates ◽  
Salmo Trutta ◽  
Swimming Activity ◽  
Food Abundance ◽  
Individual Growth ◽  
Food Level ◽  
General Tendency ◽  
Brown Trout Salmo Trutta ◽  
Juvenile Brown Trout

We studied the benefit of being territorial as an effect of food abundance by measuring the proportions of individuals that displayed a territorial, floating (individuals occasionally displayed territorial behaviour), or nonterritorial (shoaling) behaviour strategy, and individual growth rates. Also, swimming activity was monitored as an indicator of emigration. Replicate groups of 12 juvenile brown trout (Salmo trutta) were released into an artificial stream channel, fed according to one of four food regimes for 10 days, and allocated to one of three behaviour categories. There was no significant relationship between food abundance and the number of territorial individuals. Instead, the proportions of individuals that displayed the alternative behaviour strategies, i.e., floating and nonterritorial, changed with food abundance. At the lowest food level, more individuals displayed nonterritorial than floating behaviour, but these two strategies were equally represented at the highest food level. The difference in growth rates with respect to behaviour category was highest at intermediate food levels. At the highest and lowest food levels, nonterritorial fish and floaters grew nearly as fast or as poorly, respectively, as the territorial individuals. Swimming activity between the two sections of the stream tank was greatest at the lowest food level, and there was a general tendency (not significant) for the floaters to exhibit the greatest activity.

Effects of brown trout, Salmo trutta L., on the distribution of some native fishes in three areas of southern Victoria

1980 ◽  
Vol 31 (1) ◽  
pp. 61 ◽  
Author(s):  
PD Jackson ◽  
WD Williams
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
The Other ◽  
Circumstantial Evidence ◽  
Native Fish ◽  
Introduced Fish ◽  
Brown Trout Salmo Trutta ◽  
Native Fishes ◽  
Yarra River

Eight species of native fish and two of introduced fish were found during studies of the distribution of fishes in streams in three areas of southern Victoria; namely in the upper part of the catchment of the Yarra River, in the Otway Ranges, and on Wilsons Promontory. S. trutta does not occur on Wilsons Promontory, but does occur in the other two areas. Results provide circumstantial evidence that S. trutta has deleteriously affected the occurrence of Galaxias olidus and possibly G. brevipinnis. Some native fishes appear able to coexist with S. trutta.

Ghrelin increases food intake, swimming activity and growth in juvenile brown trout (Salmo trutta)

2014 ◽  
Vol 124 ◽  
pp. 15-22 ◽  
Author(s):  
Ana B. Tinoco ◽  
Joacim Näslund ◽  
María J. Delgado ◽  
Nuria de Pedro ◽  
Jörgen I. Johnsson ◽  
...  
Keyword(s):  
Food Intake ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Swimming Activity ◽  
Brown Trout Salmo Trutta ◽  
Juvenile Brown Trout

Capture–Recapture Experiment with Fly-Caught Brown (Salmo trutta) and Rainbow Trout (S. gairdneri)

1986 ◽  
Vol 43 (4) ◽  
pp. 896-899 ◽  
Author(s):  
L. D. Favro ◽  
P. K. Kuo ◽  
J. F. McDonald
Keyword(s):  
Rainbow Trout ◽  
Data Base ◽  
Brown Trout ◽  
Salmo Trutta ◽  
The Other ◽  
Capture Recapture ◽  
Capture Method

A data base on angler-captured brown (Salmo trutta) and rainbow trout (S. gairdneri) in the Au Sable River of Michigan is analyzed and compared with electrofishing data. The angling recapture frequency for brown trout increases rapidly with increasing length, while the recapture frequency for rainbow trout is independent of length. Anglers caught a greater number of fish over 33 cm long than did the electrofishers in the same water. The anglers and the electrofishers appear to have captured fish from different subpopulations; therefore, conclusions based on data obtained by one capture method may not be applicable to the other.

Seasonal Activity and Feeding Pattern of Brown Trout (Salmo trutta) in a Dartmoor Stream in Relation to Availability of Food

1969 ◽  
Vol 26 (8) ◽  
pp. 2165-2171 ◽  
Author(s):  
I. Chaston
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Stomach Contents ◽  
Total Activity ◽  
The Other ◽  
Brown Trout Salmo Trutta ◽  
The Difference ◽  
The Times ◽  
Maximum Occurrence ◽  
Terrestrial Material

In laboratory tests, brown trout were most active between dusk and dawn from spring to autumn, but the percentage of the total activity that occurred during daylight was higher in the summer than in the other two seasons. Analysis of the variation in the weight of stomach contents during 24 hr in the three seasons showed a higher peak in weight at noon in summer than in the other seasons. The difference was related to an increased consumption of material of terrestrial origin, which other work showed to be most available to the fish between 09.00 and 12.00 hr. No relationship was found between the times of maximum occurrence of benthic and emergent items in the stream and of their consumption by trout. The increase in daytime activity during the summer was also evidently related to increased consumption of terrestrial material.

Considerations on the vulnerability of the Eurasian water shrew Neomys fodiens to the presence of introduced brown trout Salmo trutta

Biologia ◽  
2016 ◽  
Vol 71 (6) ◽  
Author(s):  
Rocco Tiberti ◽  
Emiliano Mori
Keyword(s):  
Brown Trout ◽  
Aquatic Ecosystems ◽  
Salmo Trutta ◽  
The Other ◽  
Introduced Fish ◽  
Major Threat ◽  
Other Hand ◽  
Brown Trout Salmo Trutta ◽  
Semiaquatic Mammals ◽  
Neomys Fodiens

AbstractIntroduced fish represent a major threat for aquatic ecosystems and species and their impact on semiaquatic vertebrates, such as amphibians, has been extensively studied. On the other hand, little is known about their impact on semiaquatic mammals, such as water shrews (

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