scholarly journals Behavioural effects in juvenile brown trout in response to parental angling selection

2020 ◽  
Vol 77 (2) ◽  
pp. 365-374 ◽  
Author(s):  
Nico Alioravainen ◽  
Pekka Hyvärinen ◽  
Anssi Vainikka

Fishing that selectively captures and removes fish based on their behavioural decisions is predicted to induce evolution towards timid fish stocks. Thus, offspring behaviour should associate with parental vulnerability to angling. We examined phenotypic behavioural variation in juvenile brown trout (Salmo trutta) whose parents, representing a hatchery and a wild stock, were experimentally grouped based on their relative vulnerability to angling. The F1 offspring from highly vulnerable (HV) and low vulnerable (LV) parents were reared in common garden conditions together with a crossbred wild × hatchery reference group and tested for boldness during their first summer. Wild LV juveniles were the shyest of all fish, but not distinctly shyer than wild HV juveniles. Contradictorily, hatchery LV juveniles expressed bolder behaviour than hatchery HV juveniles. We show that angling selection may have transgenerational behavioural effects independently of size variation, but changes in behaviour can manifest differently in fish from different backgrounds. Our results partly support the earlier findings of increased angling-induced timidity in wild populations and thus call for management focus on behavioural effects of fishing.

2020 ◽  
Vol 32 (1) ◽  
Author(s):  
Hannah Schmieg ◽  
Sven Huppertsberg ◽  
Thomas P. Knepper ◽  
Stefanie Krais ◽  
Katharina Reitter ◽  
...  

Hydrobiologia ◽  
2016 ◽  
Vol 775 (1) ◽  
pp. 139-151 ◽  
Author(s):  
E. R. Winter ◽  
J. S. Tummers ◽  
K. Aarestrup ◽  
H. Baktoft ◽  
M. C. Lucas

2003 ◽  
Vol 81 (4) ◽  
pp. 684-692 ◽  
Author(s):  
Eva Brännäs ◽  
Sara Jonsson ◽  
Hans Lundqvist

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.


Author(s):  
Anna Hagelin ◽  
Eva Bergman

Abstract Worldwide declines in salmonid populations have generated major interest in conservation and restoration of wild populations and riverine habitats. Species reintroductions to previous habitats raises questions about their potential impact on these systems. In River Klarälven, landlocked Atlantic salmon (Salmo salar) has been extinct from upper reaches for over 50 years due to hydropower dams. Here we study competitive interactions between salmon, grayling (Thymallus thymallus) and brown trout (Salmo trutta), that occur in the upper reaches of the river. We examine foraging rates, aggression and activity of juvenile fish in allopatry at three different densities and in sympatry with one or both potential competitors in laboratory flumes. Salmon captured prey less frequently in the presence of brown trout and grayling, whereas grayling and brown trout were unaffected by salmon, but affected each other. Grayling was the most aggressive and active species whereas salmon the least. Consequently, re-introduction of salmon probably will have little impact on grayling and brown trout, whereas grayling and brown trout could affect the success of re-introducing salmon.


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