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

• Published in: Behavioral ecology and sociobiology Vol. 70; no. 12; pp. 2111 - 2125
• Main Authors: Näslund, Joacim, Johnsson, Jörgen I.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer 01.12.2016; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Aggressiveness; Animal aggression; Animal behavior; Animal Ecology; Animal personality; Behavioral Sciences; Behavioral Sciences Biology; Behavioral syndrome; Biological Sciences; Biologiska vetenskaper; Biomedical and Life Sciences; Body size; Compensatory growth; Ecology; Ekologi; Energy reserves; Etologi; Evolutionary Biology; Evolutionsbiologi; Fish; Fish feeding; Food; Food availability; Food rationing; Food restriction; Foraging; Foraging behavior; Health risks; Human aggression; Life Sciences; Mirror aggression; Mortality risk; Open-field activity; Original; Original Article; Repeatability; Salmo trutta; Size; Starvation; Swimming; Trout; Young animals; Zoology; Repeatability; Compensatory growth; Mirror aggression; Open-field activity; Behavioral syndrome; Animal personality; Food restriction
• ISSN: 0340-5443; 1432-0762
• DOI: 10.1007/s00265-016-2215-y

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 prédation probability against the risk of starvation. Here, we investigated whether brown trout Salmo trutta adjust their behavior in relation to energetic status and body size during a major early-life selection bottleneck, when fast growth is important. Over two consecutive time periods (P1 and P2; 12 and 23 days, respectively), food availability was manipulated, using four different combinations of high (H) and low (L) rations (i.e., HH, HL, LH, and LL; first and second letter denoting ration during P1 and P2, respectively). Social effects were excluded through individual isolation. Following the treatment periods, fish in the HL treatment were on average 15-21 % more active than the other groups in a forced open-field test, but large withintreatment variation provided only weak statistical support for this effect. Furthermore, fish on L-ration during P2 tended to be more actively aggressive towards their mirror image than fish on -ration. Body 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 brown trout fry adopt distinct behavioral strategies early in life.